EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: Leo Bodnar on July 08, 2017, 12:06:34 pm
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Executive summary: (updated 1st September 2017)
40-50 picosecond risetime (and even faster falltime) generator with 1V peak to peak 10MHz squarewave output. Has trigger output.
Powered and configured from USB. Ships ready to use.
BNC jack for direct connection to your test equipment.
Designed and hand-built in the UK.
Available in stock for £49.99 (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295)
Update January 2018:
2.92mm version (~30ps): http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=302 (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=302)
SMA version (~32ps): http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=303 (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=303)
(http://www.leobodnar.com/files/Pulser-RevD4.jpg)
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Here is a simple pulse generator I have made for testing medium BW scopes' risetimes. This explains BNC connector on the PCB.
It produces flat top signal with clean and fast rise and fall edges.
I had a few different designs built, using CML and LVPECL drivers, fast comparators and laser diode drivers. Some are good, some bad, some with 400mVpp, some 2Vpp, some well 50R terminated, some not. Not a grave issue for launching pulse directly into oscilloscope 50R input but it might be a problem for some applications I have. Still working on them - my target is ~40ps trise/tfall in the most compact volume.
With 4 or 5 Jim Williams avalanche generators I made over the years I never felt satisfied with the result. Jim's pulser design is infinitely tweakable (which is a blessing and a curse) and needs some work before it becomes a risetime testing device from slew rate limit testing device. I wish Jim wrote an app note on the distinction between slew rate and rise time and their practical limits. A lot of people I have talked to don't understand the difference. I had an opamp design guy being unable to explain why ideal RC network has characteristic risetime but no slew rate limit. Avalanche design does not have clean fall edge either. Anyway, I did not want another avalanche pulser.
This one is the simplest, based on 572 comparator from AD.
It shows 60ps rise and fall time on CSA803A with SD-26 head. Unlike most scopes, CSA803A cannot trigger from observed signal itself (only from external trigger input) so I had to use an ugly contraption of BNC-N-type-SMA with a T-piece to pick up part of the signal and feed it into the trigger. This does not help signal integrity but I'm reasonably happy with 60ps in such a setup.
I have attached a few oscilloscope screenshots I had around.
Tek CSA 803A with SD-26 (20GHz) 62ps risetime / 59ps falltime
Agilent MSO-X 3024A (200MHz) 1.6ns
LeCroy DDA-125 (1.5GHz) 295ps
LeCroy WavePro 7300A (3GHz) 143ps
All risetimes are for 10%-90% levels into internally terminated 50R scope inputs.
UPDATE =============== UPDATE =================== UPDATE
Gentlemen,
I have finished the configuration software and I call the project ready to ship.
You can adjust output level from 50mV to 1.2V peak-to-peak and flip the trigger/output phase in case you are using sampling scope.
Settings are non-volatile, stored in the device and survive power off.
There is a user calibration multiplier if you want to fudge voltage levels to read reasonably accurate value.
Output matches indicated value to about 5-10%. But above 1000mVpp actual and indicated output start diverging due to output current source saturation.
Rise and fall times stay reasonably low throughout the whole output range (50-1200mVpp) but to keep specified 50ps edge time keep the output level below 700mVpp.
Order yours here: USB Pulser (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295)
Many thanks for your custom!
Leo
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Very smart Leo.
I like the USB connector for the 5v (I built a USB powered JWG earlier this year), and also the tag connect for the PIC!
Any plans to sell these?
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I like the USB connector for the 5v (I built a USB powered JWG earlier this year), and also the tag connect for the PIC!
Any plans to sell these?
I'll be happy to build a few for sale if this is something useful to others.
Leo
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An alternative approach is:
- one "section" consisting of a 74lvc1g14 + 143ohm series resistor to give an output of 0->1.5V to 0->5V depending on Vcc, with an output impedance of ~150ohms
- three of those sections in parallel, to give an output impedance of ~50ohms
- driven by whatever signal is available, including a simple RC relaxation oscillator at a suitable frequency
That certainly gives a clean signal with <1ns transition time into 50ohms. I can't directly measure any faster with my 350MHz scopes. However, indirect frequency-domain measurements indicate a transition times of ~650ps, and a quick test by someone else (i.e. not verified by me) indicated ~300ps rise/fall times.
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Very useful. I am also interested in acquiring one of these if you'd be willing to sell one. What would you charge for a completed assembly?
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Very useful. I am also interested in acquiring one of these if you'd be willing to sell one. What would you charge for a completed assembly?
I'm not really interested in starting a cottage industry, thanks.
I can't guarantee those results since I can't measure them properly; I only have a Tek 485. So the price would be £1000, to enable me to buy a scope that could measure the output properly :)
They aren't that difficult to make on a double-sided pcb. The major issue is to get good power supply decoupling, which implies broad and short tracks to the Vcc and ground pins.
If you are prepared to do a bit of experimentation, then it might even be possible to make a tolerable one on a breakout board. I'd start by trying a single 74lvc1g* and a 43ohm series resistor, with an 0603 decoupling capacitor mounted diagonally on top of the 74lcv1g*; I used wirewrap wire to connect the capacitor to the pins. Edge launch SMA connectors would be the simplest connector option.
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I'll be happy to build a few for sale if this is something useful to others.
Leo
I'd gladly purchase one if you decide to build a batch.
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That looks like just the ticket, especially as it seems Vincent (https://www.eevblog.com/forum/profile/?u=446) is too busy at Tesla to make his Jim Williams implementation (http://www.siliconvalleygarage.com/projects/picosecond-pulser.html) available.
What is the plateau duration on this? I understand that is a problem with the Williams pulsers.
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Thank you for the comments, guys. I will make a batch and let you know - I have some PCBs and components left from prototyping.
This is essentially 50% duty ratio rectangular pulse so plateau duration depends on the frequency. This particular design uses internal PIC oscillator which is slaved to the USB clock to keep it simple and compact. Output frequency is 12MHz. This works fine for ordinary scopes that trigger off the same signal front they are capturing which is almost all the scopes out there apart from few sampling ones like CSA 803 / Tek 1180x / 8300. In that respect it's no different in operation than vanilla JW pulser.
Leo
edit: s/square/rectangular/
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Love it.
I would love to have one if it somehow becomes available. If you prefer not to make a (small) business out of it - I bet a few forum members would be willing to do the assembly and sell them as a courtesy service. I could run a few panels through my pick and place line and have 100 in a few hours.......not to make any money but because these things are interesting.
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Thank you for the comments, guys. I will make a batch and let you know - I have some PCBs and components left from prototyping.
This is essentially 50% duty ratio rectangular pulse so plateau duration depends on the frequency. This particular design uses internal PIC oscillator which is slaved to the USB clock to keep it simple and compact. Output frequency is 12MHz. This works fine for ordinary scopes that trigger off the same signal front they are capturing which is almost all the scopes out there apart from few sampling ones like CSA 803 / Tek 1180x / 8300. In that respect it's no different in operation than vanilla JW pulser.
Leo
edit: s/square/rectangular/
My JWG just used USB for power - be good if it didn't need a 'real' USB port to work, so it could run from everything including USB power-banks.
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My JWG just used USB for power - be good if it didn't need a 'real' USB port to work, so it could run from everything including USB power-banks.
Yep, this is how it works. USB connectivity is there "for free" and not of much importance or necessary for operation.
rx8pilot, thank you for your offer, I have few dozen PCBs remaining and it's not a big deal to assemble them manually. I'd be amazed if the world market is that huge. But stranger things happened :)
Leo
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I'd be amazed if the world market is that huge. But stranger things happened :)
Leo
Me too - I would guess a low number which is probably why these things are not commercially made even by niche manufacturers. It is a fun and educational tool to learn about though. I have been diving into high-speed digital signal integrity over the past year and it is like drinking from a fire hose. This little circuit could be fun for TDR experiments, PCB structures, and other mysterious challenges related to high-speed design. Pretty much anything even close to those rise times is huge and expensive.
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do you have a circuit diagram perhaps?
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rx8pilot, thank you for your offer, I have few dozen PCBs remaining and it's not a big deal to assemble them manually.
Did you hand solder the ADCMP572?
Also, have you thought about adding a pretrigger output?
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MK, formalising the schematic is not a priority at the moment.
Did you hand solder the ADCMP572?
Also, have you thought about adding a pretrigger output?
No, this has been reflowed.
Pre-trigger would need another connector. I'd like to keep this simple for now until it's working well.
Leo
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I'd be amazed if the world market is that huge. But stranger things happened :)
I would like to buy one unit (if possible). I was thinking about this pricey comparator before, but here you have well evaluated design, proven by equipment I don't have (sampling or > 1GHz oscilloscope) - that's a big plus.
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Pre-trigger would need another connector.
It could just be a couple of header pins.
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U would like to register too for such a device. Albeit I concur with edavid that a pretrigger output would come handy.
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This looks great to check my S-6 sampling head on my trusted Tek scope.
Had to change a switching amp in it.
It does seem to function fine now but this would be the acid test as the risetime is supposed to be 30ps.
In theory the switching amp should not have affected the sampling diodes but who knows.
I would be interested in getting one too. External trig output is also a neat idea.
Cheers and thanks.
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I already have some PCBs here so I'd like to use them but I'll see what I can do with pre-trigger output for the next batch.
What time delay (if any) between the pulse and pre-trigger are you thinking of?
Leo
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I already have some PCBs here so I'd like to use them but I'll see what I can do with pre-trigger output for the next batch.
What time delay (if any) between the pulse and pre-trigger are you thinking of?
The Tek 7T11 requires 75ns, so you could just make it one clock period.
I don't know if there are other samplers that require a greater delay.
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OK, for the next spin I am going to remove the MCU, use 10MHz TCXO as a frequency reference and break out LVCMOS buffered pre-trigger.
With 10MHz stable repetitive signal sampling scopes can trigger on the nearest edge which is 50ns away or next one at 100ns.
Buffered TCXO cycle-to-cycle jitter is probably going to be in the order of of few ps but this is not going to be a deal breaker - hopefully.
In a pinch this can also be used as a 10MHz reference oscillator or source of harmonics-rich signal.
Leo
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As an example my S-53 trigger recognizer can take a trigger input up to 100 MHz so your present rep rate of 12 MHz should not be an issue at all.
Since this is a sampling scope the time delay is not that important (the main plugin is used as a TDR after all, so I can add a delay at will) but trig jitters are.
Often I have to amplitude divide the signal and go through an amp and divide by 100 Hittitte chip to generate the trigger. Not ideal as this can corrupt the signal.
In it's present form just a 12 MHz pulse in sync with either the rise or fall of the waveform would be OK since for a sampling scope the sync jitter will be the real issue.
It looks like I could use your present design directly. But just a test point on the board with a trigger output ( buffered from the test signal) would be very nice indeed.
Have fun!
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Update: I have added an SMA with trigger output and re-spun the boards.
I should have them tuned and tested by early next week.
Thanks
Leo
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I think I have the design ready. I am very happy with its performance and form-factor. I might continue tweaking it a little bit but it's necessary to declare any project ready to ship at some point. So it is.
Here is the list of features it has ended up with.
- Fixed 10MHz pulse train with fast rise and fall times.
- Rise time and fall time around 50ps
- Variable amplitude between 100mVpp and 1Vpp (via USB .) AC coupled.
- Trigger output ~1.5Vpp amplitude into 50R load. AC (default) or DC (solder jumper) coupled
- BNC jack for direct connection to oscilloscope input
- USB powered. Power requirement is 200mA at 5V. Can be powered from a USB charger.
I have about a dozen PCBs and can supply them starting from next week at £50 plus shipping for a fully assembled, tested and ready to go unit. This will barely cover my design costs and if this becomes a commercial product will probably be revised (up or down.)
As a bonus I will print out individual rise/fall time screenshots for each unit on my CSA 803A + SD-26 test setup for this run and supply them with the device.
It would be helpful if you indicate your interest by posting here so that I know how many units to assemble.
Thanks
Leo
P.S. I hope this is not considered heavily commercial for this forum. If you think it is please let me know.
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I have about a dozen PCBs and can supply them starting from next week at £50 plus shipping. This will barely cover my design costs and if this becomes a commercial product will probably be revised (up or down.)
It would be helpful if you indicate your interest by posting here so that I know how many units to assemble.
I would be interested, but please clarify, £50 for the PCB, PCB + parts or assembled kit?
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I would be interested, but please clarify, £50 for the PCB, PCB + parts or assembled kit?
Fully assembled, tested and ready to go unit.
Thanks
Leo
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Then count me in :)
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I would be interested, but please clarify, £50 for the PCB, PCB + parts or assembled kit?
Fully assembled, tested and ready to go unit.
Thanks
Leo
Totally. Want. One. :-+ :-+
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Definitely, I'd take one if I may, thank you!
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I too would be interested in this device.
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I want one too! :D
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Put me down for one also.
Cheers and thanks.
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I'm good for one as well
paul
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+1 please and thank you
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Thank you, gentlemen. I'm on it.
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let us know if you put up a preorder/page list :-+
i WANT one when they'll be ready, but would you consider in the future a new version, powered by let's say 2 coin cells? instead of having to connect a usb cable...
where did you get your pcb made? i like them very much, simillar to the boards from one of our assemply houses (they're quite expensive to set up though, for hobby projects)
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Great job!
If your batch isn't sold out, I would also love to buy one.
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I will try to accommodate everyone :) Thanks, guys.
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Add me to the list too please.
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One for me, if you can ship to US. I'm happy to take a single US shipment as remail them to final destination.
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You can set up a public Google Docs spreadsheet and link it, people can add their names to the list. Worked well for me, no need to trawl through posts to see who wanted one :-+
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May I order one. Thank you.
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I would like to buy one too
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one more please...
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Thanks, all. The purpose of having people expressing interest is so that I can estimate suitable batch size and purchase components in correct quantities. This has worked great so far, I see that I need to run another batch of PCBs early next week.
Thank for your offer electrolust, I can ship with FedEx or Airmail around the world from our small office so this is not a problem. We get good rates.
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Count one in for me too ...
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Leo,
awesome! I would like to buy one, too!
Regards,
Andreas
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Put me on the list. Another great forum project showing up on a great forum.
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I have assembled and tested all the last revision boards I had.
They all have identical rise/fall time and profiles to within +-2ps. Therefore, I won't be printing individual screenshots like I planned before - they all look the same within my measurement capabilities. I have attached representative screen captures for the whole batch.
I am planning to finish output level configuration software this weekend and start shipping immediately and reorder more PCBs and parts.
I did not expect that level of interest - for which I am grateful :)
Thanks
Leo
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I'm in for one, thank you. :-+
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I would also be interested in one? Just PM me with details.
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I'm in for two boards
thanks
Michael
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If they are still available then I would like to register my interest, thank you.
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I intend to keep making them until there is interest so don't panic, everyone who wants one will have a chance to get one.
Leo
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You can put me down for one unit also. I appreciate the effort you put into this project. Thanks from everyone.
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I intend to keep making them until there is interest so don't panic, everyone who wants one will have a chance to get one.
Leo
sweet!
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Gentlemen,
I have finished the configuration software and I call the project ready to ship.
You can adjust output level from 50mV to about 1.2V peak-to-peak and flip the trigger/output phase in case you are using sampling scope. Not much of exciting science. Settings are non-volatile, stored in the device and survive power off.
There is a user calibration multiplier if you want to fudge voltage levels to read reasonably accurate value. Output matches indicated value to about 5-10%. Rise and fall times seems to stay the same throughout the whole output range (50-1200mVpp.)
I have 12 units in stock available here for shipping on Monday July the 17th: USB Pulser (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295)
The next batch is coming on Wednesday so I am going to continue taking orders after the first 12 are gone. If you order does not ship on Monday, don't panic it's being assembled, tested, calibrated and shipped this week.
Many thanks for this fun!
Leo
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Looks good!
Thank You! We Appreciate your Business!
Your Order Number is: 20498
Thanks.
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excellent :-+ will order this week
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Nice, already went ahed and ordered mine.
Im curious how will it look like on my 4GHz scope.
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Placed my order as well, thank you for making this available, much appreciated!
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Cheers, guys. This is probably an ultimate case of impulse buying.
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In response to my previous posting indicating my interest I just placed an order on your website a few minutes ago :)
Will be interesting how my sampling scope signal looks with your unit.
Software is a very nice touch too.
Cheers.
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Count me in for one unit.
Ordered one unit. Looking forward to playing with this on my Lecroy WavePro 960 and Tek 2465A.
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I'll be happy to build a few for sale if this is something useful to others.
Leo
If you build some, I am interested in buying one.
Thanks
Really good work!
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Cheers, guys. This is probably an ultimate case of impulse buying.
Impulse buying? Never! you can't measure risetime with an impulse :P
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Thank You! We Appreciate your Business!
Your Order Number is: 20505
Thanks, I just ordered one on your website
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Also it would be nice if the frequency was adjustable from a range of choices. For example this is useful for TDR measurements of cables and if you have a long cable then you need a lower frequency than 10MHz in order for all the reflections to make it back before the next pulse. Perhaps make it a choice of 10MHz 1MHz 100KHz 10KHz 1KHz.
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Your Order Number is: 20506 (Just placed order on website)
Thanks
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Also it would be nice if the frequency was adjustable from a range of choices. For example this is useful for TDR measurements of cables and if you have a long cable then you need a lower frequency than 10MHz in order for all the reflections to make it back before the next pulse. Perhaps make it a choice of 10MHz 1MHz 100KHz 10KHz 1KHz.
Yes, I have considered TDR use for long cables. This would need quite a redesign as opposed to just a tweak. For example, current version has AC coupled output and 10MHz pulse droop on 50R load is only a few percent across the pulse span.
With 1kHz the output would have to be DC coupled which will need a redesign and re-qualification of the frontend. The tradeoff will probably include losing crisp pulse fronts and going back to 100+ps risetimes. Isn't spread spectrum TDR all the rage now for new designs anyway?
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Just placed the order. Look forward to pulsing. Thanks Leo - looks like a nice clean design
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Also it would be nice if the frequency was adjustable from a range of choices. For example this is useful for TDR measurements of cables and if you have a long cable then you need a lower frequency than 10MHz in order for all the reflections to make it back before the next pulse. Perhaps make it a choice of 10MHz 1MHz 100KHz 10KHz 1KHz.
Yes, I have considered TDR use for long cables. This would need quite a redesign as opposed to just a tweak. For example, current version has AC coupled output and 10MHz pulse droop on 50R load is only a few percent across the pulse span.
With 1kHz the output would have to be DC coupled which will need a redesign and re-qualification of the frontend. The tradeoff will probably include losing crisp pulse fronts and going back to 100+ps risetimes. Isn't spread spectrum TDR all the rage now for new designs anyway?
Ah right i didn't know there was an AC coupling limitation with it. Makes sense to have a fixed frequency then. The 10MHz is enough for about 10m of cable anyway.
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Hi Leo,
Just ordered one on your website.
Could you provide the schematics ?
Thanks
Jacques
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Hi Leo,
Just ordered one on your website.
Could you provide the schematics ?
Thanks
Jacques
Hi Jacques,
Thank you. I don't have ready to go schematics at the moment. There is just a PIC and the driver. I am still tweaking and changing it between revisions.
Leo
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Order placed. Thanks!
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Order 20535 placed. Thks!
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hi and congrats,
any chance to have a version with adjustable frequency.
I'm personnally interested in a low frequency version.
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any chance to have a version with adjustable frequency. I'm personnally interested in a low frequency version.
Low/adjustable frequency needs substantial redesign. Maybe something for v.3
Leo
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good to know, thanx
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Order 20515 received with thanks!
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Where do I find the website ?
paul
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Hi Paul,
http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295 (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295)
I have shipped all the boards that I had. All outstanding orders will ship by the end of this week.
Cheers
Leo
Where do I find the website ?
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The pulser arrived today - neat little gadget, need to buy a box for it.
I didn't try the trigger out or USB connectivity yet, just a simple test with my WaveRunner 6100A. 50 Ohm termination, RIS mode (i.e. equivalent sampling, in real time it is 10-15 ps worse), the rise time is around 240 ps, well under the datasheet specification of 300 ps.
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Mine too arrived yesterday, but sadly it came during a brief period when no one was home so it is now gone to the sorting office :(
My wife went to the sorting office today with the little card, but they wouldn't give it to her because it was addressed to me and she didn't have any id for me. |O
Tomorrow, my wife has kindly agreed to have another go, taking my ID with her - so perhaps I'll get it tomorrow evening when I return from work.
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Update: I have sent out all orders received over the weekend. Thank you!
There are three remaining units ordered yesterday and day before yesterday awaiting new PCB batch. They will be shipped on Friday or Monday.
Cheers
Leo
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This device will add a few entries into the 'Show us your square wave' thread.
I think that mine has arrived - my wife is checking. Looking forward to a quick check on the 6Ghz Keysight scope!
Looking forward to various TDR experiments. It will be a nice tool to learn a little about high-speed design which is consuming my efforts at the moment.
EDIT:
Arrived in the USA - 70ps rise - 20% overshoot. Curious about the overshoot, was more than expected based on the test report that Leo included.
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I got mine here in USA Tuesday. Here's the rise on my R&S RTO1014 1 GHz scope, 295 picoseconds.
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Got mine today after one missed delivery and two trips to the post office.
About 750 psecs on my 350MHz scope which is nearer the 500MHz BW rather than 1 ns specified rise time.
I can't remember what rise time I got with my Jim Williams pulser - I need to check for a comparison.
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This device will add a few entries into the 'Show us your square wave' thread.
most definetly.
about the overshoot, are you positive that the scope frontend has a gaussian responce? or maybe there is some parasitics? same for the wavejet screenshot...
@Leo, i haven't placed an order yet, do you still have one of them on stock? i have both keysight and a lecroy's reps coming over next week with loaners :)
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about the overshoot, are you positive that the scope frontend has a gaussian responce? or maybe there is some parasitics? same for the wavejet screenshot...
@Leo, i haven't placed an order yet, do you still have one of them on stock? i have both keysight and a lecroy's reps coming over next week with loaners :)
I will make as many as needed, there is a new batch of PCBs coming tomorrow (Friday.) I will try to assemble, test and ship everything tomorrow or in the worst case - on Monday.
Regarding overshoot - I am not sure about exact dynamics of the total system, the PCB itself seems to be reasonably well damped - I have about 10% overshoot that dies down after 50ps on 20GHz SD-26. Both of my LeCroys show higher and longer overshoot - this makes me think that it is coming from either frontend response or DSP processing rather than the pulser.
When it comes to really fast risetimes you typically have to choose between fastest risetime possible or minimum aberrations. Jim Williams touched on that subject in his AN94.
There is an interesting series of appnotes from Picosecond Pulse Labs written by James Andrews that contain risetime results of numerous scopes and discussion of pulsers used:
https://kh6htv.files.wordpress.com/2015/11/an-02a-oscopes.pdf
https://kh6htv.files.wordpress.com/2015/11/an-02b-oscopes.pdf
https://kh6htv.files.wordpress.com/2015/11/an-02c-oscopes.pdf
https://kh6htv.files.wordpress.com/2015/11/an-02d-oscopes.pdf
https://kh6htv.files.wordpress.com/2015/11/an-02e-oscopes.pdf
It looks like PSPL uses two different pulsers - one for risetime measurements and the other for ringing, flatness and settling time measurements.
Leo
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The overshoot is quite small - 79.1mV out of 1.363V which is only 6%.
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Regarding overshoot - I am not sure about exact dynamics of the total system, the PCB itself seems to be reasonably well damped - I have about 10% overshoot that dies down after 50ps on 20GHz SD-26. Both of my LeCroys show higher and longer overshoot - this makes me think that it is coming from either frontend response or DSP processing rather than the pulser.
yes, which i why i have asked :)
I tested my 500 MHz lecroy 7242B with a 1ns-rise/fall time pulse (trigger output from another scope, the fastest i could generate here at home) and it showed a nice and clean edge, i'm sure i'm not pushing it enough ;)
I am aware of the bandwidth/risetime tradeoff, which is of course pretty obvious if one thinks of the relationship between frequency responce and the need of sufficient attenuation to not incur in aliasing at a given real-time samplerate
I remember reading somewhere here in the forum that higher bandwidth keysight and/or lecroy had not a gaussian response, which is why i asked it in the first place
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I think that scopes below about 1GHz BW (I'm not certain of this dividing line though) are Gaussian while "high end" ones are not:
http://www.tek.com/support/faqs/how-bandwidth-related-rise-time-oscilloscopes (http://www.tek.com/support/faqs/how-bandwidth-related-rise-time-oscilloscopes)
I'm pretty sure that my WaveJet is Gaussian.
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Have a look at the image in reply ##89. The R&S RTO1000 series scopes are specifically designed to have a gaussian response. The result I got is dead flat on the rising edge, but has some pre-undershoot. The RTO1014 1 GHz scope is spec'd to have a 350 ps rise, and Leo's pulser gives me a 295 ps rise time.
I also have read that Tek and Keysight digital scopes don't have a gaussian frequency response.
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Not all scopes have an USB port :) I've powered up the old Tek 2467 and well 1.3 ns sounds a bit slow for a 350 MHz scope.
But I bought it "for parts or repair" so maybe there is something more to fix.
Edit: My bad, wrong graticule for the right cursor. So 1ns which seems OK for 350 MHz.
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I love it but it will be nice to have to have differential output instead of just single ended output for TDR Applications like measuring
twisted pair cable.
adcmp572 has already that capability.
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I got mine here in USA Tuesday. Here's the rise on my R&S RTO1014 1 GHz scope, 295 picoseconds.
It looks like there is maybe some sin(x)/x post processing here, causing that pre-ringing, and obscuring the real waveform.
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Today mine arrived. I guess my TDS580 wins the prize for the most ringing display
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Your pulse generator arrived today in Germany, thanks for the fast shipment.
One question.
When I run your software on my PC, (Win7), I get weird selection numbers for the voltage selection.
Is it the software or anything I am missing?
See attachments
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Your pulse generator arrived today in Germany, thanks for the fast shipment.
One question.
When I run your software on my PC, (Win7), I get weird selection numbers for the voltage selection.
Is it the software or anything I am missing?
See attachments
It looks like a decimal dot/comma confusion.
Temporary bugfix: for now assume it is in microvolts :D
I will try to change my locale and see if I can replicate and fix this.
Leo
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Aww so it doesn't have a secret 2kV output range in select European places? Would be pretty impressive with that rise time. ;D
I'm on vacation so Il know if I got mine once I get back home.
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Today mine arrived. I guess my TDS580 wins the prize for the most ringing display
It will be interesting to learn what contributes to the different responses seen on various scopes.
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OK, I will wait for you to figure out the decimal point.
Here are my measurements on my slowest scope.
This is an Agilent branded DSO-X-2002A, 70 MHz
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OK, tested on my Agilent MSO-X-3104A, 1 GHz scope
Rise time 440 ps
The software is running on an older XP
This time I get good numbers like 1000 but if I select a different number, like 1400, the signal is not changing at all.
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Now tested on my Agilent MSO 7045B 500 MHz scope
Rise Time 1.03 ns
No overshoot, may be the scope is too slow!
This time Software running on a Lenovo Laptop with Win7 Pro and all works as expected
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Now tested on my Agilent MSO 7045B 500 MHz scope
Rise Time 1.03 ns
No overshoot, may be the scope is too slow!
Don't forget to terminate input to 50R if you want fastest and cleanest risetime.
Leo
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Now my last scope for this test, a Keysight MSO-X-6004A, 6 GHz, 50 Ohm
Rise time is 88 ps
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Now tested on my Agilent MSO 7045B 500 MHz scope
Rise Time 1.03 ns
No overshoot, may be the scope is too slow!
Don't forget to terminate input to 50R if you want fastest and cleanest risetime.
Leo
You are right, I forgot the 50 Ohm setting.
Here again the same scope, 50 Ohm turned ON
Rise time 630 ps
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Just for fun I tested your pulse generator on a 20 year old Fluke PM3394B, 200 MHz
50 Ohm input
1.84 ns rise time
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Now my last scope for this test, a Keysight MSO-X-6004A, 6 GHz, 50 Ohm
Rise time is 88 ps
Assuming total system risetime Tsystem2 = Tscope2 + Tpulser2
It checks out reasonably well:
Tsystem = 88ps, Tpulser = 50ps
From there Tscope = 72ps
MSO-X-6004A specification (http://literature.cdn.keysight.com/litweb/pdf/5991-4087EN.pdf) lists 75ps risetime.
Pleasant UI on that Fluke.
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Neat to see some CROs join in even if they are hybrids.
Oh and do all your scopes have names like that?
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Found some time and tried the Wavewhatever MX104 @work
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Neat to see some CROs join in even if they are hybrids.
Oh and do all your scopes have names like that?
Only on my high voltage bench, Scope-1 to Scope-6 because I am switching the RS232 connection manually to one PC input for data acquisition.
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Found some time and tried the Wavewhatever MX104 @work
now that is pretty
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Received mine today, thank you Leo!
Here's my Rigol DS4000 series:
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=334839)
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Hi Leo,
News from order 20535?
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Hi Leo,
News from order 20535?
Hi Denis,
Shipped on the 20th of July with Airmail.
Thanks
Leo
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Mine has arrived, all good. Thanks.
Will have a look at the output on my scopes when I get home from vacation.
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Should be there today hopefully. Thks Leo
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Today we had a demo of some Tek stuff here.
I managed to get screenshots from the new MSO58 2GHz flagship. This has a frickin large screen - with lots of space for ringing. I believe my TDS580 (see somewhere above) isn't that bad in terms of Tek-ringing. I do still like more the clean edge of the LeCroy.
(first two pictures)
Then there was the fabulous fiber optic isolated probe with 500MHz bandwith - the signal looks a bit different (third picture)
Fforgot to adjust the timebase for the rise time display to work, too many people around distracting me.
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Do I see this right, the Tektronix 2GHz MSO58 has 213 ps rise time with this 50ps pulse generator ?
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Do I see this right, the Tektronix 2GHz MSO58 has 213 ps rise time with this 50ps pulse generator ?
Thtat's what I've seen. The specification (taken from Tek website) is:
Bandwidth (calculated rise time) 350 MHz (1,15 ns), 500 MHz (800 ps), 1 GHz (400 ps), 2 GHz (225 ps)
They must have different frontends for the 2GHz models, since many specs are different between 2GHz and less than 2GHz models.
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Hi Leo,
Received mine today as hoped.
Tested on Rigol MSO2302A (300MHz, upgraded...) and Tektronix 2445A (150 MHz). Results as awaited, perfect!
Rigol MSO2302A (300MHz): 1.050ns (rise), 1.090ns (fall)
Tektronix 2445A (150 MHz): 2,00ns (rise), 2,10ns (fall)
The software rose an error when launched: Error '13' uncompatible type (Windows 10).
Thanks again.
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Received mine today as hoped.
Tested on Rigol MSO2302A (300MHz, upgraded...) and Tektronix 2445A (150 MHz). Results as awaited, perfect!
The software rose an error when launched: Error '13' uncompatible type (Windows 10).
Cheers,
I am looking into the problem - looks like a decimal comma/point issue.
Leo
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I have modified the configuration software to fix the decimal comma/point issue for locales that use decimal comma.
Please try downloading new version again: http://leobodnar.com/files/pulser_configuration.exe (http://leobodnar.com/files/pulser_configuration.exe)
Thanks
Leo
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Hi Leo,
Works perfectly well now, including calibration. Thanks a lot :-+
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I have modified the configuration software to fix the decimal comma/point issue for locales that use decimal comma.
You should tell Rigol how to do that...
They say it's impossible to fix their PSU control software (https://www.eevblog.com/forum/testgear/rigol-dp832-and-ultrapower-(ultra-sigma)/msg1146919/#msg1146919).
we can't change it. All of our test devices needs point separator for communication
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I tested a few Rigol scopes with the pulse generator.
DS1102E
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=336673;image)
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=336671;image)
DS1074Z 100 MHz
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=336675;image)
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=336677;image)
DS2072 300 MHz with 1M input
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=336679;image)
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=336681;image)
DS2072 with 50R through terminator
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=336683;image)
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=336685;image)
DS4014 500 MHz
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=336687;image)
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=336689;image)
One thing that could be noticed when testing several Rigol scopes one after another was that as the series number gets higher the user experience can be quite different and feels much snappier. Well the hardware under the hood is quite different too.
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And then a few other scopes too
Keysight DSOX3014T
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=336692;image)
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=336694;image)
LeCroy WavePro 7300A
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=336696;image)
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=336698;image)
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I think it would be nice to collect the results into an online spreadsheet and a chart similar to this one - any volunteers ???
with an estimated Tpulser ~50ps the rise-times should be accurate to 10% up to 3 or 3.5 GHz - if my chart is roughly right..
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I just started a Google spreadsheet and added what's been posted in this thread so far. See attached screenshot.
Any suggested changes before I try to make it public (never made a shared one before)? What should we call it?
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I just started a Google spreadsheet and added what's been posted in this thread so far. See attached screenshot.
Any suggested changes before I try to make it public (never made a shared one before)? What should we call it?
I'd make the default sort order manufacturer and then model.
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I just started a Google spreadsheet and added what's been posted in this thread so far. See attached screenshot.
Any suggested changes before I try to make it public (never made a shared one before)? What should we call it?
awesome :-+
I'd make the X-axis the manufacturer specified BW of the scope.
maybe there's a way to make a shaded background between say 0.35/BW and 0.45/BW - where we'd expect the measurements to fall.
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Here are some of my scopes:
Tek 2246 100MHz Analog 50 ohm* 2070 2280
Tek 2465 300MHz Analog 50 ohm 1080 1260
Tek 7904/7A26 200MHz Analog 50 ohm* 1650 1700
Tek 7904/7A24 400MHz Analog 50 ohm 700 800
Rigol 1074Z 70MHz 1GS/sec 50 ohm* 3940 4570
Rigol 1074Z 20MHz 1GS/sec 50 ohm* 14630 15910 (20MHz bandwidth limit)
Siglent SDS1202X 200MHz 1GS/sec 50 ohm 1750 1790
OWon PDS8102T 100MHz 1GS/sec 50 ohm* 2040 1960
*= 1Meg input with external 50 ohm pass through terminator
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Any suggested changes before I try to make it public (never made a shared one before)? What should we call it?
Yes, add a column with Leo's calculation for the scope's rise time
see below..
Now my last scope for this test, a Keysight MSO-X-6004A, 6 GHz, 50 Ohm
Rise time is 88 ps
Assuming total system risetime Tsystem2 = Tscope2 + Tpulser2
It checks out reasonably well:
Tsystem = 88ps, Tpulser = 50ps
From there Tscope = 72ps
MSO-X-6004A specification (http://literature.cdn.keysight.com/litweb/pdf/5991-4087EN.pdf) lists 75ps risetime.
Pleasant UI on that Fluke.
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Good idea for the spreadsheet and good suggestions to improve.
Two remarks for my lines :
- first scope is in fact Rigol MSO2072A upgraded in MSO2302A (that's what appears in the system info after upgrade)
- second one is Tek 2445A, not 2445
Gixy
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Hi,
I've fixed the mistakes pointed out by Gixy, added the datapoints provided by Tom45 and added a column with the calculated scope risetime taking the risetime of the pulser into consideration. The calculated bandwidth numbers are then based on the calculated risetime.
I've opened the spreadsheet up for viewing (at least I think I have):
https://docs.google.com/spreadsheets/d/1uknvUdL4gNuTyuK7MNAkCj95GFSsDtfgr7nObVppFiE/edit?usp=sharing
I've yet to figure out the sorting stuff and I don't quite understand what graphing we should do. If anyone wants to help out just drop me a PM and I'll try to set you up with editing rights (or should I just allow full editing rights?)
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MDO3054 from TEK @ 50 Ohm.
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I've opened the spreadsheet up for viewing (at least I think I have):
https://docs.google.com/spreadsheets/d/1uknvUdL4gNuTyuK7MNAkCj95GFSsDtfgr7nObVppFiE/edit?usp=sharing
now we really need someone with a >10gig scope to confirm the intrinsic pulser rise-time ;D
https://docs.google.com/spreadsheets/d/1W7VlSqhM8XUgPErtco0ETyDvSDprG7elEpLsuc_W-FA/edit?usp=sharing
(I wanted a solid line for the Tscope+Tpulser prediction, but not sure how to do it in googledocs..)
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I've requested the edit access, can update the details on my entries.
Also, please bring back the 0.45 factor. 0.35 is useless nowadays except the analog or low-end scopes, i.e. not most scopes on the list.
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I've requested the edit access, can update the details on my entries.
Also, please bring back the 0.45 factor. 0.35 is useless nowadays except the analog or low-end scopes, i.e. not most scopes on the list.
The last three columns are 0.45/risetime, user, and comment. Perhaps you need to scroll over to see them?
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The last three columns are 0.45/risetime, user, and comment. Perhaps you need to scroll over to see them?
I was replying to awallin and in reference to his copy of the sheet.
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and here from an Agilent DL6104 @ internal 50Ohm
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57.6ps on a 20GHz HP 54120B/54121A setup, but as this uses 3.5mm/SMA connectors, I very strongly suspect the limitation is my professionally terminated BNC-SMA cable. The best I could get out of the cable from the internal <33ps rise time TDR output of the 54121A test set with that cable (and a further BNC/SMA transition) was about the same. I tried a number of BNC/SMA interseries connectors of assorted qualities (none that I'd call professional) as well as the 12" RG223 SMA-M/BNC-F cable, and the cable gave the best results.
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=337470;image)
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Hi,
Data from mk_ and Howardlong has been added, so has my own 2465B:
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=337479;image)
It does not quite live up to it's specification or I'm doing something wrong with it using the 10x mag
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Hi,
Data from mk_ and Howardlong has been added, so has my own 2465B:
It does not quite live up to it's specification or I'm doing something wrong with it using the 10x mag
It looks like your 500ps timebase is OK.
You need to adjust the vertical gain so that the square wave top is at the solid line above the top dotted line, and the square wave bottom is at the solid line below the lower dotted line. Then the two dotted lines will be at 10% and 90%. Set the two cursors where the trace crosses the 10% and 90% dotted lines.
That should give a better result.
Also, I've noticed on my analog scopes, the shape of the trace varies some between channels. Is that because the analog scopes are old and need some TLC? Or was there that much variation when they were new? I don't know.
You might want to try 1 and 2 to see if there is a noticeable difference.
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You need to adjust the vertical gain so that the square wave top is at the solid line above the top dotted line, and the square wave bottom is at the solid line below the lower dotted line. Then the two dotted lines will be at 10% and 90%. Set the two cursors where the trace crosses the 10% and 90% dotted lines.
His measurement is correct. Waveform's top and bottom should be on the dotted lines(!) and then the next solid line is the 10% and 90%. This is even marked on the overlay in the photo.
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You need to adjust the vertical gain so that the square wave top is at the solid line above the top dotted line, and the square wave bottom is at the solid line below the lower dotted line. Then the two dotted lines will be at 10% and 90%. Set the two cursors where the trace crosses the 10% and 90% dotted lines.
His measurement is correct. Waveform's top and bottom should be on the dotted lines(!) and then the next solid line is the 10% and 90%. This is even marked on the overlay in the photo.
You are right! The few times I've ever needed to measure rise time I never bothered to look at the scale. I just went with my faulty memory of what I once knew. Thanks for setting me straight.
Now I need to go back and redo my Tek analog scope measurements.
Tom
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You are right! The few times I've ever needed to measure rise time I never bothered to look at the scale. I just went with my faulty memory of what I once knew. Thanks for setting me straight.
Now I need to go back and redo my Tek analog scope measurements.
Tom
This....is what I absolutely love about this forum. I have seen it several times in the short period I have been a member; someone say, in essence "oh god, you're right, I was mistaken" this is a rare thing on the internet and to be applauded IMO.
Leo seems to have done an outstanding job on this pulser, looking forward to getting one.
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Still making these? I missed the thread initially but would love to buy one!
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Still making these? I missed the thread initially but would love to buy one!
Sure, I have them in stock.
Get yours here. (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295)
Thanks
Leo
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Still making these? I missed the thread initially but would love to buy one!
Leo has a business designing and selling items such as this pulse generator. So it should be available long term which benefits all of us.
http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295 (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295)
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Another good old analog scope: HP 1742A, 100MHz, 50 Ohm. Rise & Fall times: 3.5ns.
It is generally admitted to use 0.35 (0.356 indeed) for scopes with BW lower than 1GHz and 0,45 for the others.
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I ordered one - really looking forward to it!
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Received mine via the slow boat ... works great. I won't bother to post results, they are like everyone else's here. But I do want to comment on how professionally made and packed the device was. Wow!
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But I do want to comment on how professionally made and packed the device was. Wow!
Totally. Super sharp.
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Mine arrived last week after a really good attempt by some postal service or other to squash it...
Here is what my HP 54542A sees. I have no way of taking screenshots over GPIB from this scope (and don't feel like spending $59 for software that claims to be able to do it*) so it's a cellphone picture. The scope is set to repetitive with 8 averages.
*no, 7470.exe doesn't work with it.
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Question: Is the overshoot actually there, or it is an artifact of sin(x)/x interpolation? If it's actually there, is it part of the output or is that a byproduct of the [short] transmission line / PCB trace / etc.
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Here is what my HP 54542A sees. I have no way of taking screenshots over GPIB from this scope (and don't feel like spending $59 for software that claims to be able to do it*) so it's a cellphone picture. The scope is set to repetitive with 8 averages.
If your unit has RS232 interface available you can simply read data via RS232-USB-adapter using any terminal program such as hterm. I would recommand using gnu octave, it just takes a few commands to aquire data and plot them also live.
-branadic-
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I was surprised that the measured rise time of the Keysight MSO-X-6104A from rx8pilot was significantly faster than mine.
He measured 70 ps and my instrument had measured 88 ps
So, I measured all my 4 channels again:
Scope-Channel, t-rise, Overshoot
CH 1, 88.6, 6.3%
CH 2, 87.9, 6.8%
CH 3, 82.7, 9.8%
CH 4, 83.2, 8.6%
Still about 12 to 18 ps slower than the rx8pilot data.
May be it is related to the overshoot.
Leo Bodnar:
I would like to buy another pulser from you but I would like you to make sure it has the smallest possible overshoot, like in the picture from rx8pilot or even less.
Is that possible that you pre-select one?
Or what do you think is the difference between the measurements of these two scopes?
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I would like to buy another pulser from you but I would like you to make sure it has the smallest possible overshoot, like in the picture from rx8pilot or even less.
Is that possible that you pre-select one?
All units are quite consistent in their parameters - within 1-2% overshoot and ±4ps risetime.
I can try critically damping the output to have no overshoot - it will increase the risetime by ~10ps.
I am going to make another batch tomorrow or on Friday and will try tweaking one unit.
At the moment I only have 20GHz SD-26, 12.5GHz SD-22 and 3GHz WavePro 7300A to go by.
Leo
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Question: Is the overshoot actually there, or it is an artifact of sin(x)/x interpolation? If it's actually there, is it part of the output or is that a byproduct of the [short] transmission line / PCB trace / etc.
My LeCroy WaveRunner 6100A (1 GHz) screenshot was without sin(x)/x. I can redo the measurement with sin(x)/x turned on and we'll see the difference.
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I would like to buy another pulser from you but I would like you to make sure it has the smallest possible overshoot, like in the picture from rx8pilot or even less.
Is that possible that you pre-select one?
All units are quite consistent in their parameters - within 1-2% overshoot and ±4ps risetime.
I can try critically damping the output to have no overshoot - it will increase the risetime by ~10ps.
I am going to make another batch tomorrow or on Friday and will try tweaking one unit.
At the moment I only have 20GHz SD-26, 12.5GHz SD-22 and 3GHz WavePro 7300A to go by.
Leo
Then it seems I was wrong and want the opposite.
I want the fastest possible rise time, so I need a larger overshoot?
Can you tweak that too?
In a way to match the one from rx8pilot
Here is his picture again:
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At the moment I only have 20GHz SD-26, 12.5GHz SD-22 and 3GHz WavePro 7300A to go by.
Leo
"only" ;D
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I don't have an msox6000 series, but I'd assume there's a way to change to equivalent time sampling as there is on the mso7000 where it's in the Acquire menu. Switching to equivalent time on my mso7104b and 54831d (masquerading as a 54832d) significantly improves rise time figures, I assume because of sampling aliasing errors in real time mode, but I wouldn't be surprised if the filtering may be changed somewhat too.
This ties into the overshoot that brick wall filters typically create, employed in real time sampling especially at higher speeds closer to the sampling rate, in an effort to avoiding aliasing problems. More gentle Gaussian filters avoid the overshoot but are more prone to aliasing: it's good old fashioned engineering compromise at work. It's also why the rise time/bandwidth calculation fudge factor changes.
There are a number of Keysight docs on the phenomenon, for example http://literature.cdn.keysight.com/litweb/pdf/5988-8008EN.pdf (http://literature.cdn.keysight.com/litweb/pdf/5988-8008EN.pdf)
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I don't have an msox6000 series, but I'd assume there's a way to change to equivalent time sampling as there is on the mso7000 where it's in the Acquire menu. Switching to equivalent time on my mso7104b and 54831d (masquerading as a 54832d) significantly improves rise time figures, I assume because of sampling aliasing errors in real time mode, but I wouldn't be surprised if the filtering may be changed somewhat too.
This ties into the overshoot that brick wall filters typically create, employed in real time sampling especially at higher speeds closer to the sampling rate, in an effort to avoiding aliasing problems. More gentle Gaussian filters avoid the overshoot but are more prone to aliasing: it's good old fashioned engineering compromise at work. It's also why the rise time/bandwidth calculation fudge factor changes.
There are a number of Keysight docs on the phenomenon, for example http://literature.cdn.keysight.com/litweb/pdf/5988-8008EN.pdf (http://literature.cdn.keysight.com/litweb/pdf/5988-8008EN.pdf)
Yes, there is a similar menu in the 6000X scope
I tried following Data Acquisition Modes:
- Realtime = 88,5 ps
- Realtime (Max Update Rate) = 88,5 ps
- Equivalent time = 89.4 ps
I also tried the different acquisition modes:
- Normal
- Peak detect
- Averaging
- High Resolution
But the rise time will always be around 88ps, compared to rx8pilot's 70 ps.
Thanks for the link to the Keysight doc, I will study it.
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Get yours here. (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295)
Do you need a picture to go with that? :)
(http://www.bbc.co.uk/staticarchive/8d699778fc7c07a52e7516e29e392322f9051e4a.jpg)
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Here is what my HP 54542A sees. I have no way of taking screenshots over GPIB from this scope (and don't feel like spending $59 for software that claims to be able to do it*) so it's a cellphone picture. The scope is set to repetitive with 8 averages.
If your unit has RS232 interface available you can simply read data via RS232-USB-adapter using any terminal program such as hterm. I would recommand using gnu octave, it just takes a few commands to aquire data and plot them also live.
-branadic-
Thanks for the hint.
I had totally forgotten that this puppy has a floppy drive. If the drive is working...
So, I found a suitable floppy, found the disk menu, saved the image in TIFF format, read it in using an external USB drive on the Mac, converted it to PNG and uploaded it.
This image is while the scope is still building up the trace in repetitive mode. No connecting of the dots at this point. It sure shows that the overshoot is real on this scope.
I found the scope's spec and rise time is spec'd at 700ps. I guess 475ps is quite acceptable!
Edit: The 1.333ns max rise time isn't real - it's an artifact of how the repetitive sampling works.
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What is the calibration adjustment for? The peak to peak voltage output?
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Mine arrived last week after a really good attempt by some postal service or other to squash it...
Here is what my HP 54542A sees. I have no way of taking screenshots over GPIB from this scope (and don't feel like spending $59 for software that claims to be able to do it*) so it's a cellphone picture. The scope is set to repetitive with 8 averages.
*no, 7470.exe doesn't work with it.
It should. I don't have one of those but I've had success reports from at least one other user. I have a note from another user with a 54502A that says that the listen-only option needs to be selected in 7470.exe's GPIB menu. Give that a try, maybe, and hit 'w' to make it wait for a plot. What happens if you press the plot button on the 54542A?
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Mine arrived last week after a really good attempt by some postal service or other to squash it...
Here is what my HP 54542A sees. I have no way of taking screenshots over GPIB from this scope (and don't feel like spending $59 for software that claims to be able to do it*) so it's a cellphone picture. The scope is set to repetitive with 8 averages.
*no, 7470.exe doesn't work with it.
It should. I don't have one of those but I've had success reports from at least one other user. I have a note from another user with a 54502A that says that the listen-only option needs to be selected in 7470.exe's GPIB menu. Give that a try, maybe, and hit 'w' to make it wait for a plot. What happens if you press the plot button on the 54542A?
Probably not 7470.exe's fault. It's probably some 64bit OS/probably fake 82357B/Keysight libraries 488.2 support problem. 'w' gave an immediate error. I should take the Prologix ethernet adapter home and try it instead.
I think the plot button displayed some message as if it was in progress, then the message went away quietly. I'd set the GPIB settings on the scope to print to a 7470A at that point. Even in this state, 'w' in 7470.exe gave an immediate error.
I have had 7470.exe work before on the same PC with the 8568A SA, but I don't recall which adapter I used.
For now, sneaker-net with the floppy drive is working.
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What is the calibration adjustment for? The peak to peak voltage output?
It tweaks reported voltage span in the top dropdown selection. If you want Vpp reported by the application to match accurately measured actual value, adjust the calibration factor. This is not a calibration grade equipment so use it "for indication use only."
Leo
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Try setting the scope to "talk only" if possible to drive a plotter.
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GET
~IT~
HERE (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295)
Do you need a picture to go with that? :)
(http://www.bbc.co.uk/staticarchive/8d699778fc7c07a52e7516e29e392322f9051e4a.jpg) (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295)
Perfect!
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Try setting the scope to "talk only" if possible to drive a plotter.
FWIW, that's the way I made it work on an HP 54120B using a Prologix USB GPIB adapter.
As a one-off, I run the GPIB Configurator tool and select the correct COM port, Update the CONFIG.INI, and exit the configurator.
Each time I need to get some screen prints, I run the 7470A emulator (as administrator), select Display->1280x960, select View->Overlay all sources, File->Close all visible plots, and from the Plot menu on the scope I select each of the three plots, one at a time. Once I have the plots, I need I press the space bar to exit the "Listen" mode and I usually use Windows' snipping tool rather than the application to save the bitmap, no particular reason other than that's my workflow.
So in view of the above, more often than not, I just use a camera ;-)
This is Leo's 50ps generator which for some reason performed better today at 54.8ps, but I am sure a lot of that is due to my crappy BNC->SMA transition:
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=337921;image)
This is the 54121A's TDR pulse viewed on Ch1, the same channel it's generated on, note timebase is now 20ps/div:
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=337927;image)
The is the same internal TDR pulse viewed on a different channel to where it's generated, i.e. Ch3:
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=337930;image)
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I took the plunge and ordered one on Monday - having finally realised that having the time to build something similar was fantasy :)
Hope that it arrives soon.
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I took the plunge and ordered one on Monday - having finally realised that having the time to build something similar was fantasy :)
Hope that it arrives soon.
FWIW, I ordered mine on Saturday and it arrived on Tuesday (UK).
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Working great. Very high quality construction and packaging as well. Pushes the LeCry to 330ps
(http://retroactive.be/img/i/ra59839e5b60ec8a68b.jpg)
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Mine arrived last week after a really good attempt by some postal service or other to squash it...
Here is what my HP 54542A sees. I have no way of taking screenshots over GPIB from this scope (and don't feel like spending $59 for software that claims to be able to do it*) so it's a cellphone picture. The scope is set to repetitive with 8 averages.
*no, 7470.exe doesn't work with it.
It should. I don't have one of those but I've had success reports from at least one other user. I have a note from another user with a 54502A that says that the listen-only option needs to be selected in 7470.exe's GPIB menu. Give that a try, maybe, and hit 'w' to make it wait for a plot. What happens if you press the plot button on the 54542A?
Probably not 7470.exe's fault. It's probably some 64bit OS/probably fake 82357B/Keysight libraries 488.2 support problem. 'w' gave an immediate error. I should take the Prologix ethernet adapter home and try it instead.
I think the plot button displayed some message as if it was in progress, then the message went away quietly. I'd set the GPIB settings on the scope to print to a 7470A at that point. Even in this state, 'w' in 7470.exe gave an immediate error.
I have had 7470.exe work before on the same PC with the 8568A SA, but I don't recall which adapter I used.
For now, sneaker-net with the floppy drive is working.
It works with the Prologix Ethernet adapter.
Set "No assigned plotter address" on 7470.exe's GPIB menu.
Set the 54542A to talk and select HP 7470. Disable saving images to disk.
Use the 'w' command on 7470.exe.
Now the Print button on the 54542A does what it should.
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I took the plunge and ordered one on Monday - having finally realised that having the time to build something similar was fantasy :)
Hope that it arrives soon.
I spent hours researching an approach to build one - probably would have taken another few days to design it, a few days for prototype, another few days for REV B, ........ about a few weeks later, I may or may not have something that worked.
Then I saw this. Lovely. Can't wait to have a play day.
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Mine arrived last week after a really good attempt by some postal service or other to squash it...
Here is what my HP 54542A sees. I have no way of taking screenshots over GPIB from this scope (and don't feel like spending $59 for software that claims to be able to do it*) so it's a cellphone picture. The scope is set to repetitive with 8 averages.
*no, 7470.exe doesn't work with it.
It should. I don't have one of those but I've had success reports from at least one other user. I have a note from another user with a 54502A that says that the listen-only option needs to be selected in 7470.exe's GPIB menu. Give that a try, maybe, and hit 'w' to make it wait for a plot. What happens if you press the plot button on the 54542A?
For the record, a screenshot of the error I get immediately when using the w command and 82357B/Keysight IO libraries is attached. I'd have sent it as a PM, but the forum doesn't seem to allow attachments to PMs.
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Looks good.
That's a (very) old version of 7470.exe, but given the density and layout of the label text, it might actually look better than the higher-fidelity vector text renderer in the current build.
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Looks good.
That's a (very) old version of 7470.exe, but given the density and layout of the label text, it might actually look better than the higher-fidelity vector text renderer in the current build.
It was an old version - I hadn't updated that computer. I think the file dates were sometime in 2012!
I have now updated that computer and would have to say I prefer the old label text.
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Finally arrived :) :-+
Very neat gadget.
Some timings to add
LeCroy 9354T (500MHz) - 10Gs/s RIS 660-670ps
Lecroy WavePro 950 (1GHz) - 50Gs/s RIS - 270ps; 16Gs/s single-shot 280ps (no photo for the latter)
Philips/Fluke PM3394A (200MHz) analogue mode 1.72ns
Philips/Fluke PM3394A dgital mode 1.66ns
The Philips needs calibrating as there is a lot of overshoot and ringing.
(http://www.wild-pc.co.uk/images/IMG_8608.jpg)
(http://www.wild-pc.co.uk/images/IMG_8606.jpg)
(http://www.wild-pc.co.uk/images/IMG_8610.jpg)
(http://www.wild-pc.co.uk/images/IMG_8613.jpg)
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A question - is it better to look at an equivalent time sample mode or single shot mode for the rise time/fall time measurements?
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A question - is it better to look at an equivalent time sample mode or single shot mode for the rise time/fall time measurements?
From what I have seen, it looks like different scopes use different strategies and reconstruction filters in both modes. Single shot mode is typically much more challenging and usually enables sharper roll-off filters that produce more ringing. On LeCroys equivalent sampling usually shows slightly better risetime results.
I have been playing with various settings and component selection (RF 0201 and 0306 caps) for the pulser and it looks like the best risetime setting is achieved when the output level is set at around 820mV (with 1.000 calibration.) Actual amplitude as reported by the scope is 920mV and peak-peak is 976mVpp. This is including 6% overshoot. You can match them up by setting calibration adjustment to 1.118 if you want - this does not affect the signal in any way.
Also the pulser fall time is slightly (4-5ps) faster than the rise time. I can't explain why, probably output stage is marginally better at turning off.
I can't help posting a screenshot from CSA803A - only because standard deviation of risetime measurement is 800 femtoseconds. Nice, woody word :)
And yes, 11800/CSA803 user interface is not elegant.
Leo
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Maybe I missed it, but which output driver (the one branded AJK BAA) are you using in the latest revision?
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Maybe I missed it, but which output driver (the one branded AJK BAA) are you using in the latest revision?
MAX3949
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Lecroy WaveSurfer 62MXs-B, 600 MHz, 5GS/s, 50R DC
average rise-time 551.6 ps - no surprises there 8)
the fall-time was jumping around a lot - may try this again later with more time/care.
more scopes at work to follow - cheerio :-+
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Hi,
Received my pulser some time ago. Thanks Leo. Two screenshots attached, using the default settings of the pulser.
First is a Tek TDS7254 (2.5 GHz 20 GS/s), connected via a TCA-BNC adapter.
The second one is a R&S (Hameg) HMO3052 (500 MHz 4 GS/s).
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Keysight DSOX1102G, 70 MHz, 1G
4.4 ns rise time.
Micsig MS220T, 200 MHz
1.7 ns rise time.
Tell me if anyone want screenshots.
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I received mine today!
Are all the measurements being done here 10%/90% or 20%/80% ?
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I received mine today!
Are all the measurements being done here 10%/90% or 20%/80% ?
10%/90% surely?
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Are all the measurements being done here 10%/90% or 20%/80% ?
There is a long tradition of using 10%-90% when measuring rise time of analogue (asynchronous) signals.
Digital is all messy:
USB 2.0 specify rise time for 10%-90% levels.
PCI Express, HDMI and most logic level specs use 20%-80%.
Maybe it's low voltage swing, maybe improved receivers and reclockers tolerance, maybe it just looks better.
Conversion factor between them for a gaussian response system is about x1.6 which is substantial, so when in doubt - spell it out.
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Thanks Leo - pulser works great!!
Rise/fall averaged across all channels.
Pico 2207B (70 MHz): rise=2512, fall=2421 (50 ohm passthrough)
Pico 2407B (70 MHz): rise=2686, fall=2564 (50 ohm passthrough)
HP 54645D (100 MHz): rise=2375, fall=2375 (50 ohm passthrough)
BK 2120 (20 Mhz): rise=20000 (50 ohm passthrough, it was 2/5 of a graduation where the graduation was 50nS)
Rigol DS2072 (300 MHz): rise=980, fall=994 (50 ohm passthrough)
Rigol DS4014 (500 MHz): rise=653, fall=647 (50 ohm built-in)
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Got mine today. Nice packing job, perfect. Thanks Leo. Love the trig output. :)
As stated in my earlier post here I wanted to check my old Tek S6 sampling head after changing a sampling-and-hold Tek opamp with a generic one. I am using a 7s12 TDR plugin with a s-53 trigger recogniser for this measurement.
Using the 10-90% I got about 58ps rise-time. As 100% I used the high level after the ringing stopped. I also assumed the pulser supplied trace showing a rise-time of 49.2ps for the unit as correct as I do not know the specs of the measuring instrument. I assume it is much better than my old stuff ::) If true, that gives me 30.7ps for the S-6 unit using the usual the t^2 sum equation. It's specifications are 30ps rise-time.
Not bad considering how old it is! ;D
Next step will be to test my R7912 transient digitizer for its single shot 1GHz bandwidth.
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I also assumed the pulser supplied trace showing a rise-time of 49.2ps for the unit as correct as I do not know the specs of the measuring instrument. I assume it is much better than my old stuff ::)
I have two CSA803A in very good condition, looking almost brand new inside and a variety of sampling heads, one SD-30 (40GHz) and a number of SD-26(20GHz) and SD-22(12.5GHz.)
They are all from different sources and I have cross-checked them against each other - they all agree within noise floor limits.
This is old equipment from 1990's so it hardly makes any sense to get calibrated, especially for the fun project like this.
I use CSA803A with SD-26 head (17.5ps nominal risetime) installed to print the slips I include with each pulser I send away.
I have tested few units on SD-30 (8.8ps risetime) and there is only 2-3ps difference in the total result - as expected.
Overall I am quite happy with the pulser design performance so will leave it as it is for now.
Leo
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Thanks for the trace information Leo. :)
The risetime numbers do make sense then, even if I shave a few ps to deconvolve your trace.... well within experimental error.
""Overall I am quite happy with the pulser design performance so will leave it as it is for now.""
Agreed! The unit is a very nice piece of work, don't mess with greatness. :)
I believe my S-6 sampling head with about 10GHz bandwidth is circa 1970s vintage so your equipment is positively modern by my standards :-+
Can't wait to see what you come up with as an encore.
Cheers and thanks.
rich
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Gentlemen,
Thanks to all of you who supported me by buying one of the pulsers!
To date, the feedback was very good, performance was excellent and very stable.
All current devices show risetime between 40 and 50ps and falltime around 40 ps.
I have received new PCB batch and keep assembling the pulsers to maintain stock levels. They ship same/next working day.
If you wanted to get one - get it now, there is no guarantee that it will be available forever.
Cheers
Leo
http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295 (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295)
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Update 21 September 2017.
I have been slightly tweaking the design between the batches to milk a bit more performance out of it.
Latest batch of the pulsers that I have assembled today all show risetime and falltime below 40ps.
I use two CSA803As with two cross-checked SD-30 40GHz sampling heads to individually test each and every unit.
Here are the rising and falling edge screenshots from a typical fully assembled pulser.
If you still want one - get it while you can.
Thank you for your interest, gentlemen.
Leo
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Would like to tell you about my 40psec device received recently.
it comes with printed measurements: Pulser_40psec_Leo_Bodnar_Measurement_web.jpg - awesome ;)
Unfortunately, my Tektronics 2465B appears to be a bit slow: Pulser_40psec_Leo_Bodnar_2465B_50R_rise_web.jpg
RiseTime => 284 MHz
FallTime => 320 MHz
My Hameg HM407 is better than spec: Pulser_40psec_Leo_Bodnar_HM407_rise_web.jpg
RiseTime => 41 MHz
FallTime => 45 MHz
Out of curiosity I connected the device to my GPS synced counter: Pulser_40psec_Leo_Bodnar_52320A_web.jpg
< 32 mHz Allan Deviation is quite good...
Looks like I've got an easily transportable 10 MHz reference in addition ;)
Cheers
Ulli
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There’s a limitation on the 2465B and 2467B auto measurement system which aflicts fast signals.
You’ll have to do it manually with your #1 eyeball and the graticule & cursors, with a vertical vernier and x10 timebase setting I’m afraid to get a decent response.
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Here's my 2467b
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=356606;image)
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I got my generator today.
Here are measured rise times from my Tektronix scopes 2465B and 7904.
Tek 7904 has 7T11 and 7S11 (with S-4) plug-ins installed. I used internal triggering.
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More pictures made with my pulser (first batch):
S4 sampling head / 7S12 in 7603 Mainframe
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=359862)
S2 sampling head / 7S12 in 7603 Mainframe
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=359864)
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Two more
Tek 468 in non-store (analog 100MHz BW) mode, 5ns/div
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=359867)
Tek TDS420
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=359869)
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Here are rise and fall time pictures from Tektronix TDS3032:
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Tek 2465A (refer to Buy/Sell forum if you want it!).
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50ps pulser + PicoScope 2408B with 50ohm passthru.
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=360206)
...and first experiment. Tried to get actual pulses instead of square. At the end of tower is short:
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=360208)
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=360210)
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Tektronix 7103R with 7A29 and 7B15 plug ins. Rise time is about 310 ps.
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[/img]
...and first experiment. Tried to get actual pulses instead of square. At the end of tower is short:
Impulse response can be mathematically determined from the step response, just differentiate. Then you can get the system frequency response from that impulse response by taking FFT.
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Impulse response can be mathematically determined from the step response, just differentiate. Then you can get the system frequency response from that impulse response by taking FFT.
That's another story :) In this case was specifically interested in creating physical pulse, not characterize scope etc. In fact I could not characterize scope in original software with this method anyway because:
It will do derivative just fine. Even agrees to do FFT on it. But due to some bug wont render trace :-BROKE And even if it would no use. FFT trace is hard-limited to 100MHz. Because it is officially 100MHz scope. Actually it is ~140MHz scope of course. I hate when excellent hardware is crippled by "almost there" programming + politics.
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=360225)
Edit: MatLab seems to do the supposed thing, 3.2dB diff 10MHz vs 150MHz:
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=360345)
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Here is rise time for Tektronix 2247A:
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Here are a couple of screenshots from my Lecroy WavePro 960 (2 GHz, 16 GS/s).
Trace "A" is an average of the channel under test (for noise reduction).
Trace "B" is the derivative d/dt of A. Note the vertical scale of 1 GV/s per div!
Trace "C" is the FFT of B.
Trace C gives the frequency response of the oscilloscope and pulser (and any cable connecting them, none in this case).
Trace A shows rise time of 268 ps. Using the relation 0.45/Tr=BW, it estimates 1.68 GHz. Obviously such rules of thumb are not universally applicable. The actual -3 dB point in Trace C is 2.03 Ghz.
It can be shown mathematically that an impulse has equal energy at all frequencies. So, if you pass an impulse through a system, you can measure the frequency response by looking at what went through. Generating an actual impulse is impractical, largely because generating one with enough energy to measure practically presents difficulties. For example, an impulse that delivering the same energy to the system as does a 50 ps 1 V rising edge, would require a 50 ps wide, 20 000 000 000 volt pulse. I can't generate 20 GV in my lab, and my scope input wouldn't like it if I could :scared: Actually, we don't quite need that much energy but it is still difficult to generate a well-behaved impulse. Fortunately, we can use math trickery instead. We know that the d/dt of a step is an impulse. The "d/dt of the response to a step" is the same as the "response to the d/dt of a step" (response to an impulse). So we apply a fast rise step to the system, measure system step response, then take d/dt of the step response to get the system impulse response. Then convert to frequency domain (take FFT) to get frequency response. That is exactly what is shown in Trace C.
In this case, the frequency response can be seen varying about +/- 1 dB from zero to 2 GHz, and dropping extremely rapidly after 2 GHz. The -3 dB point relative to DC is 2.03 GHz.
I have a variable filter (Krohn Hite 3202r), which can do high pass, low pass, bandpass, and notch modes with a continuously variable corner/center frequency. It can be entertaining to set up the scope to display the frequency response in real time while playing with the filters.
p.s. MrW0lf, confine your FFT to a single period and you'll get the nice flat-top result. In this case, you want the DC imbalance that is present in the impulse response.
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=360372;image)
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=360374;image)
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macboy, thanks for clarifications. I will play with pulser later and try to reproduce by-the-book result. Have not tried this before because of software issues. Only recently got MatLab because stuff not doable in original software started to pile up.
BTW I had to use multiple periods because just extracted raw data - 1GSa/s non averaged is not sufficent - small number of periods will just show garbage.
As for my original physical impulse shot - I have interest in solitons, but no fancy indoor waveguide:
https://www.youtube.com/watch?v=w-oDnvbV8mY (https://www.youtube.com/watch?v=w-oDnvbV8mY)
So have to do it small and with electricity much like this:
https://youtu.be/I9m2w4DgeVk?t=11m46s (https://youtu.be/I9m2w4DgeVk?t=11m46s)
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TEA got me again, I just ordered one.
Very interesting results. Since I am pretty virgin on this topic:
https://www.edn.com/electronics-blogs/bogatin-s-rules-of-thumb/4424573/Rule-of-Thumb--1--The-bandwidth-of-a-signal-from-its-rise-time (https://www.edn.com/electronics-blogs/bogatin-s-rules-of-thumb/4424573/Rule-of-Thumb--1--The-bandwidth-of-a-signal-from-its-rise-time)
http://literature.cdn.keysight.com/litweb/pdf/5988-8008EN.pdf (http://literature.cdn.keysight.com/litweb/pdf/5988-8008EN.pdf)
Sorry if was already posted somewhere here...
EDIT:
of course was already there:
https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/msg1271710/?topicseen#msg1271710 (https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/msg1271710/?topicseen#msg1271710)
EDIT2:
@Leo Bodnar, Did you post it in the Buy/sell section? I coudn't find it, such a nice product deserves more customers...
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Ok, tried hard to get it right:
ETS monster style: 20GSa/s, single wfm (zoomed), averaged, 1kpts:
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=360424)
Get nice smooth graph but overly optimistic.
RTS style: 1GSa/s, many wfms (zoomed on single), averaged, 1Mpts:
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=360426)
Detailed FFT, quite realistic result.
Possibly there are issues with approach MatLab Signal Analyzer uses:
https://se.mathworks.com/help/signal/ug/spectrum-computation-in-signal-analyzer.html (https://se.mathworks.com/help/signal/ug/spectrum-computation-in-signal-analyzer.html)
Interesting which low end scopes could actually pull this off in native GUI? GW Instek possibly? It's a shame Picos cant do it - its not by design but by some stupid bug :(
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Here is rise time from Tektronix 7904 with plug ins 7A29 and 7B92A. It is about 600 ps.
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I have been to the Electronics Design Show in Coventry (UK) earlier today and dropped by our friends from Tektronix and Pico Technology.
Thanks to James from Tek and Kieran and Trevor from Pico Tech for testing the pulser. It is not easy to demo your complicated top line equipment live when everybody is watching - especially to test a surprise customer device. When I have showed up both scopes were set up to run demos for eye pattern tests and TDR but engineers were more than happy to rip the setup apart and connect my unknown DUT - both scopes worked flawlessly and we had great fun.
Tektronix had 33GHz BW, 100Gsps realtime DPO73304SX scope (https://www.tek.com/datasheet/scalable-performance-oscilloscopes) on their stand and the pulser edge speed result was 31ps.
Pico Technology demoed 20GHz BW sampling scope with TDR capability (https://www.picotech.com/oscilloscope/9300/picoscope-9300-sampling-oscilloscopes) which measured the pulser risetime at 34ps.
Leo
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What a nice opportunity top test your pulse generator.
And great pictures, thanks for sharing.
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BTW, later I managed to partially work around fft(derivative(signal)) issue on Pico RTS range software also, described here (https://www.eevblog.com/forum/testgear/picoscope-2000/msg1323831/#msg1323831). Hope in future some wizardry gone into ETS software can be channeled down the range so could do fun stuff with less effort.
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Wow! The Tek scope reports 30.851912 psec rise time. :-DD
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I have been to the Electronics Design Show in Coventry (UK) earlier today and dropped by our friends from Tektronix and Pico Technology.
Thanks to James from Tek and Kieran and Trevor from Pico Tech for testing the pulser. It is not easy to demo your complicated top line equipment live when everybody is watching - especially to test a surprise customer device. When I have showed up both scopes were set up to run demos for eye pattern tests and TDR but engineers were more than happy to rip the setup apart and connect my unknown DUT - both scopes worked flawlessly and we had great fun.
Tektronix had 33GHz BW, 100Gsps realtime DPO73304SX scope (https://www.tek.com/datasheet/scalable-performance-oscilloscopes) on their stand and the pulser edge speed result was 31ps.
Pico Technology demoed 20GHz BW sampling scope with TDR capability (https://www.picotech.com/oscilloscope/9300/picoscope-9300-sampling-oscilloscopes) which measured the pulser risetime at 34ps.
Leo
That is really cool!
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I realise it might be a bit niche, but a native SMA or 3.5mm version might perform even better!
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I realise it might be a bit niche, but a native SMA or 3.5mm version might perform even better!
It would need total redesign to show appreciable improvement.
I have tested SMA version today and apart from subtle changes it did not have much advantage over BNC.
Also consider the fact that BNC version test result includes SMA-BNC interseries connector.
Leo
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I realise it might be a bit niche, but a native SMA or 3.5mm version might perform even better!
It would need total redesign to show appreciable improvement.
I have tested SMA version today and apart from subtle changes it did not have much advantage over BNC.
Also consider the fact that BNC version test result includes SMA-BNC interseries connector.
Leo
Understood, but... you’re assuming I am in the ownership of a kickass bnc-f to sma-m interseries adapter. I have a couple decent amphenol ones going the other way. A decent interseries adapter would cost significantly more than your generator ;-)
I realise t’internet can obscure wry smiles, which is how I wrote my last message and write this one too: I know it’s not a simple part replacement, it’s a board respin and test, and there’s unlikely to be much of a market, but I live in hope, until I can find a decent reasonably priced interseries adapter of course!
In the meantime, thanks for your product, it’s certainly appreciated here.
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Hmmm, did you take your existing board and simply replace the BNC with an appropriately dimensioned SMA? I migt be interested in doing that mod, if it’s that simple and I can find the SMA male with the right mount. It might mean I’ll have to buy another pulse generator, of course.
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Hmmm, did you take your existing board and simply replace the BNC with an appropriately dimensioned SMA? I migt be interested in doing that mod, if it’s that simple and I can find the SMA male with the right mount. It might mean I’ll have to buy another pulse generator, of course.
Howard, I can do this for you (or anyone else) if you want. This is, perhaps, slightly ugly looking but mechanically and performance-wise very solid. There are 0201 components near the central pin solder joint so if you are doing it yourself make sure you don't sweep them off. You know your components are small when they fall down through the vias.
I can put male or female SMA and set it at 90 degrees, not skewed like below. SMA female was quite expensive (http://uk.farnell.com/radiall/r125433000/rf-coaxial-sma-straight-plug-50ohm/dp/8591148) so I'd need to charge an extra £10 for this version.
In fact, you are welcome to this one that you see on the pictures and risetime plot. Photos are of the actual item. :D
Leo
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I have tested SMA version today and apart from subtle changes it did not have much advantage over BNC.
Also consider the fact that BNC version test result includes SMA-BNC interseries connector.
Leo
It's not that the performance of the BNC connector is unacceptable in itself, it's that the whole idea behind a fast pulser is to test fast hardware. Having to use a BNC-to-SMA adapter with a fast DUT is certainly worse than having to use an SMA-to-BNC adapter with a slower DUT.
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It's not that the performance of the BNC connector is unacceptable in itself, it's that the whole idea behind a fast pulser is to test fast hardware. Having to use a BNC-to-SMA adapter with a fast DUT is certainly worse than having to use an SMA-to-BNC adapter with a slower DUT.
I accept your reasoning but I had problems with people not being able to find suitable USB cable locally.
Looks like I'd have to make and stock SMA version as well at some point.
Leo
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It's not that the performance of the BNC connector is unacceptable in itself, it's that the whole idea behind a fast pulser is to test fast hardware. Having to use a BNC-to-SMA adapter with a fast DUT is certainly worse than having to use an SMA-to-BNC adapter with a slower DUT.
I accept your reasoning but I had problems with people not being able to find suitable USB cable locally.
Looks like I'd have to make and stock SMA version as well at some point.
Leo
Would it make sense to go with SMA on the next spin, and sell an optional BNC adapter to go with it?
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Hmmm, did you take your existing board and simply replace the BNC with an appropriately dimensioned SMA? I migt be interested in doing that mod, if it’s that simple and I can find the SMA male with the right mount. It might mean I’ll have to buy another pulse generator, of course.
Howard, I can do this for you (or anyone else) if you want. This is, perhaps, slightly ugly looking but mechanically and performance-wise very solid. There are 0201 components near the central pin solder joint so if you are doing it yourself make sure you don't sweep them off. You know your components are small when they fall down through the vias.
I can put male or female SMA and set it at 90 degrees, not skewed like below. SMA female was quite expensive (http://uk.farnell.com/radiall/r125433000/rf-coaxial-sma-straight-plug-50ohm/dp/8591148) so I'd need to charge an extra £10 for this version.
In fact, you are welcome to this one that you see on the pictures and risetime plot. Photos are of the actual item. :D
Leo
You’re on: PM me the total inc P&P with your Paypal details.
FWIW, 0201 not a problem here. Sometimes I go down to 01005 if I have to. 008004 not yet encountered, probably just a matter of time though the way things are going. Meh, 0201 passives going down vias, I had a 3x2 ball CSP do that on me recently. Losing a $0.001 passive is one thing, a $3 chip feels much less of a write off, especially if you’re down to your last 2 or 3 contingency parts on a prototype.
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I ordered one last week, should arrive today :)
One suggestion: could you please share the protocol specs to configure it? A Windows program is very inconvenient for someone not using Windows. It should be very easy to implement in Python, at least for simple command-line usage.
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Looks like I'd have to make and stock SMA version as well at some point.
Leo
Leo,
If you ever release a SMA version, I am interested in getting a 3rd pulse generator from you.
Thanks!
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Seeing that most people are using these to test scopes i think a BNC is pretty welcome.
That being said i do tend to use SMA for everything and since test equipment usually does not have SMA i have a bunch of SMA to BNC and to N cables.
Is it possible to give it a dual footprint that takes both? Then have the BNC one be the standard version while the special version having no connector soldered and provide one SMA in the kit (Some other non SMA connectors also fit)
That being said is this thing actually useful for RF stuff? Like maybe being a comb generator or something. I never tried mine on a spectrum analyzer.
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That being said is this thing actually useful for RF stuff? Like maybe being a comb generator or something. I never tried mine on a spectrum analyzer.
As a TDR to examine coaxial cable runs?
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That being said is this thing actually useful for RF stuff? Like maybe being a comb generator or something. I never tried mine on a spectrum analyzer.
I have tried it on 8595E just now.
Green trace is SA noise floor.
Leo
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One suggestion: could you please share the protocol specs to configure it? A Windows program is very inconvenient for someone not using Windows. It should be very easy to implement in Python, at least for simple command-line usage.
I'll try putting something together. You can only adjust output level and inversion, so it's not very exciting.
Leo
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One suggestion: could you please share the protocol specs to configure it? A Windows program is very inconvenient for someone not using Windows. It should be very easy to implement in Python, at least for simple command-line usage.
I'll try putting something together. You can only adjust output level and inversion, so it's not very exciting.
Thanks! If you have a simple description I can try to implement it in Python myself. Needless to say I'll share the program.
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I have tried it on 8595E just now.
Green trace is SA noise floor.
Leo
How did you capture that trace from the HP 8595E so clearly?
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How did you capture that trace from the HP 8595E so clearly?
Thanks to KE5FX and his software - I did not have a proper chance to say how good and useful his stuff is!
http://www.ke5fx.com/gpib/readme.htm (http://www.ke5fx.com/gpib/readme.htm)
I'd wish for the font to line-up slightly better but I believe it is vectorised and compiled into the code.
I have spent exactly 30 seconds on this issue because it is not a problem at all, just nit-picking.
Leo
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Here is measured spectrum (blue) against theoretical spectrum of ideal square wave (red) - only odd harmonics are shown for clarity.
My SA has not been calibrated for ages but it does not look too bad.
Leo
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How did you capture that trace from the HP 8595E so clearly?
Thanks to KE5FX and his software - I did not have a proper chance to say how good and useful his stuff is!
http://www.ke5fx.com/gpib/readme.htm (http://www.ke5fx.com/gpib/readme.htm)
I'd wish for the font to line-up slightly better but I believe it is vectorised and compiled into the code.
I have spent exactly 30 seconds on this issue because it is not a problem at all, just nit-picking.
Leo
You're welcome -- credit goes to texaspyro for his work on the renderer. :-+ You can try displaying the plot with 7470_legacy.exe to use the old fixed-width font, but for everything that looks better, something else will tend to look worse. HP-GL is hard to get right.
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Received yesterday, nice piece of kit!
I didn't have much time but I tried it on a Siglent SDS1202X-E and a "grown up" Rigol DS1074Z (using a T BNC adapter and a SMA 50 ohm terminator from the miniVNA Tiny calibration kit) and it works very well. I even did a quick and dirty TDR with a piece of coax.
Hoping to have more time this week, I'll post the screenshots.
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How did you capture that trace from the HP 8595E so clearly?
Thanks to KE5FX and his software - I did not have a proper chance to say how good and useful his stuff is!
http://www.ke5fx.com/gpib/readme.htm (http://www.ke5fx.com/gpib/readme.htm)
I'd wish for the font to line-up slightly better but I believe it is vectorised and compiled into the code.
I have spent exactly 30 seconds on this issue because it is not a problem at all, just nit-picking.
Leo
You're welcome -- credit goes to texaspyro for his work on the renderer. :-+ You can try displaying the plot with 7470_legacy.exe to use the old fixed-width font, but for everything that looks better, something else will tend to look worse. HP-GL is hard to get right.
Yep, HP-GL rendering is a royal pain... there is basically no way to "get it right". There are a LOT of interpretations of what HP-GL should do and it seems that everything that spews HP-GL somewhere does it wrong / different. It was a lot of work getting the HP-GL2 renderer to handle all the example files in the gpibkit install. You tweak it for one oddball, fubar'd instrument and it borks another one. Anyway, 7470.exe has one of the most capable HP-GL renderers out there... at least for instrument dumps ;) The CERN viewer is also very good: http://service-hpglview.web.cern.ch/service-hpglview/hpglviewer.html (http://service-hpglview.web.cern.ch/service-hpglview/hpglviewer.html)
I originally wrote the HP-GL renderer to use with my Atmel 2561 based GPIB controller that emulates a Prologix serial GPIB interface. It was done as sort of a joke, but turned out to be rather useful. It could display instrument screen dumps (HP-GL or PCL) on a 160x80 monochrome LCD touchscreen. The fonts used are vector fonts that were generated from a VGA dot matrix font (and are the same fonts used in Lady Heather and my gcode processor program).
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Hello KE5FX and texaspyro
Many years ago, I tried to find a software to collect a screen shot from my old HP spectrum analyzer, until I gave up. Now I am surprise to hear that there is something.
Thank you so much !
I am traveling right now, but I will test this on the weekend, when I am back.
You should start a separate thread on this, I think lots of people would be interested.
In the olden days, when I had a HP plotter, I was always curious why the plotting sequence was sometimes very odd. And every plot that was made, was different in sequence. May be that was also a problem in programming a capture software for HP/GL?
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Agilent 54622D 100MHz 200MS/s: Avg rise time 7.47 ns, Real-time average acquisition, 5 ns timebase
Agilent 54622D 100MHz 200MS/s: Avg rise time 2.77 ns, Average acquisition, 5 ns timebase
Agilent 54642D 500MHz 2GS/s: Avg rise time 0.7 ns, Real-time average acquisition, 1 ns timebase
Agilent 54642D 500MHz 2GS/s: Avg rise time 0.63 ns, Average acquisition, 1 ns timebase
LeCroy LC534AM 1GHz 10GS/s: Avg rise time 0.31 ns, RIS (Random Interleaved Sampling) acquisition, 1 ns timebase
LeCroy J-250 1GHz 16GS/s (WavePro 950): Avg rise time 0.246 ns, Single-shot acquisition, 0.5 ns timebase
Works great! Thank you, Leo! :-+
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Agilent 54622D 100MHz 200MS/s: Avg rise time 7.47 ns
Works great! Thank you, Leo! :-+
That seems slow for a 100MHz 'scope - should be around 3.5ns?
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I've updated the spreadsheet with all the entries so far.
In the spreadsheet all calculated bandwidths are based on a pulser risetime of 50ps which we now know is quite concervative, especially with Leo's 2nd generation units. As is, the spreadsheet doesn't even handle the 31ps to 34ps figures properly.
The spreadsheet is here:
https://docs.google.com/spreadsheets/d/1uknvUdL4gNuTyuK7MNAkCj95GFSsDtfgr7nObVppFiE/edit?usp=sharing
If anyone want access to it just PM me your email adress and I'll add you to the list.
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@H.O
Hi,
You forgot my post #156 for the HP 1742A in the table.
Cheers,
Denis
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@H.O
In my post 207 the rise time of Tek 7904 with 7T11 and 7S11 (with S-4) is less than 60 ps (not 80 ps).
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Here is an other picture with 50 ps time base.
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That seems slow for a 100MHz 'scope - should be around 3.5ns?
It's because the real-time sampling rate is low.
I've updated my reply.
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That seems slow for a 100MHz 'scope - should be around 3.5ns?
It's because the real-time sampling rate is low.
I've updated my reply.
Running the 54642D in equivalent time might improve its rise time performance a little too, certainly I've found that on other Agilent/Keysight scopes that support it (e.g. MSO7104B, 54832D).
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Running the 54642D in equivalent time might improve its rise time performance a little too, certainly I've found that on other Agilent/Keysight scopes that support it (e.g. MSO7104B, 54832D).
I've updated my reply once again.
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..
LeCroy J-250 1GHz 16GS/s (WavePro 950): Avg rise time 0.246 ns, Single-shot acquisition
..
Works great! Thank you, Leo! :-+
I hate that your 1 GHz J-250 (WavePro 950 ish) is faster than my 2 GHz WavePro 960. But I've confirmed a -3dB point just above 2 GHz on the 960 so it does live up to spec. And my overshoot and ringing looks very different than yours. Curious.
Can you try the same bandwidth measurement technique that I used in my post (https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/msg1323191/#msg1323191)? This will show you not only the -3 dB point but also the passband ripple of the scope. It's nice to know those things. You may or may not have deep FFT support on your unit depending on options (look for WAVA or WAVAPRO or WPRO in options list).
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Can you try the same bandwidth measurement technique that I used in my post (https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/msg1323191/#msg1323191)?
Yes, here's pictures.
LeCroy J-250 1GHz 50GS/s (WavePro 950): Avg rise time 0.251 ns, RIS (Random Interleaved Sampling) acquisition, 5 ns timebase
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Can you try the same bandwidth measurement technique that I used in my post (https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/msg1323191/#msg1323191)?
Yes, here's pictures.
I must try this with the 950, though I know it only has the "vanilla" FFT
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Can you try the same bandwidth measurement technique that I used in my post (https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/msg1323191/#msg1323191)?
Yes, here's pictures.
Nice, way beyond spec. And a nice rolloff, not the brick wall that the 960 has.
I guess you could change your name to 1.8GHz now. :-DD
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Said in my previous post that I would try it on my Tek R7912AD.
This is a single shot transient digitizer with a 500MHz bandwidth (about 1GHz direct access).
The 10 to 90% risetime looks to be around 700ps.
Using the risetime ~ 0.35/bandwidth guide I get 500MHz...... 8)
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Update 21 September 2017.
I have been slightly tweaking the design between the batches to milk a bit more performance out of it.
Latest batch of the pulsers that I have assembled today all show risetime and falltime below 40ps.
You mentioned a few revisions to get a better performance. I have your Rev E batch rated as 50ps. From the photo I can see a few modifications in the upper right.
Is this something that I can retrofit on the old board or would that be too tricky?
:)
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You mentioned a few revisions to get a better performance. I have your Rev E batch rated as 50ps. From the photo I can see a few modifications in the upper right.
Is this something that I can retrofit on the old board or would that be too tricky?
:)
Current revision is Rev.G and I have modified power bypass quite a lot. So the short answer is "tricky" :)
The best I can offer you is another one from current Rev.G with a discount. But 50ps is pretty darn fast as it is.
Leo
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Thanks Leo.
Since 50ps is already much faster than anything I own right now I'll be OK for the next while!
I was just intrigued on how you did it and if it was easily transferable to the previous version when I saw your posting.
Cheers.
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Said in my previous post that I would try it on my Tek R7912AD.
This is a single shot transient digitizer with a 500MHz bandwidth (about 1GHz direct access).
The 10 to 90% risetime looks to be around 700ps.
Using the risetime ~ 0.35/bandwidth guide I get 500MHz...... 8)
Now that is quite a beast. I had to look it up and its pretty interesting.
http://w140.com/tekwiki/wiki/7912 (http://w140.com/tekwiki/wiki/7912)
Turns out back in 1973 they made this work using a CRT tube with a plate of detectors on the end(That are also read with a electron beam like a vidicon tube) to create a high speed AD converter.
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HP 16530A 100MHz 400MS/s: Avg rise time 3.4 ns, Average acquisition, 5 ns timebase
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Thank you to those who pointed out some mistakes and omissions in the spreadsheet (on and off list).
I believe I've fixed those now and I've added the last day(s) entries.
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Can you try the same bandwidth measurement technique that I used in my post (https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/msg1323191/#msg1323191)?
Yes, here's pictures.
I must try this with the 950......
And the result is:
(http://www.wild-pc.co.uk/images/IMG_9282.jpg)
Not quite as good as 1GHz's machine, but not too shabby.
Out of interest the Lecroy is good for this analysis as it makes it easy to use the output of one maths function as the input to another - that does not seem to be the case for a Keysight DSO1024A or Tenma 72-8725 that I have recently had to play with - it could simply be that I've not figured out how to get them to play ball but both of these 'scopes seem to have fairly shallow memories and only do FFT based on what is on screen.
What other 'scopes can do this analysis to show the impulse power spectrum?
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I was able to convince my Phillips PM3320A (ca. 1987) to do it, but it wouldn't the horizontal of the FFT result as frequency, only as points. I guess the firmware designers didn't anticipate users doing FFT of a d/dr of a waveform. Anyway the resulting FFT just wasn't as convincing as the WavePro result. I manually measured the -3dB bandwidth as 375 MHz, not bad for a 200 MHz scope.
Is your WavePro actually as grey as it looks in the photo? My 960 is a distinctive blue-grey that is actually quite ugly.
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Is your WavePro actually as grey as it looks in the photo? My 960 is a distinctive blue-grey that is actually quite ugly.
Blue-grey is about right, no attempt was made for accurate colour balance in the above shot so the camera has almost certainly interpreted the front panel as mid grey and adjusted accordingly.
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Here i tried the pulsar on a Agilent MSO9204H.
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=366649;image)
Doing a FFT of a derivative is easy here since it has 16 math channels to choose from and each can feed in to the next.
About what is to be expected with a rise time of 147ps and the FFT showing a -3dB bandwith at 3.1GHz.
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With a Leo SMA modded version on an HP 54120B & 54121A combo, 35.6ps. (I was getting about 55ps on the BNC version with a rather generic BNC-SMA interseries adapter of indeterminate provenance).
I feel sure I may be able to do better with some experimentation: still it's almost as good as the scope's internal pulse generator (~33ps).
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=366686;image)
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That is pretty cool.....especially for a tiny $75 device.
Glad I got one.
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I got in my pulser a couple of days ago. A couple of new measurements for the table:
Tek TDS3034 (non-A) up-hacked to TDS3054: 560 ps / 715 MHz
Tek THS730A: 1.4 ns / 285 Mhz
Used 0.4 / rise time for the calculation.
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Got mine a week or so ago. Build quality is excellent and it works great!
Results:
Agilent 54832D 1000 331
Tektronix TDS784A 1000 270
Tektronix TDS3052 500 620
Tektronix TDS694C 3000 106
Agilent 54855A 6000 68
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Got mine a week or so ago. Build quality is excellent and it works great!
Results:
Agilent 54832D 1000 331
Tektronix TDS784A 1000 270
Tektronix TDS3052 500 620
Tektronix TDS694C 3000 106
Agilent 54855A 6000 68
I had to look up the Agilent model number 54855A.
It is a real-time scope with a bandwidth of 7 GHz?
Nice result of 68 ps!
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Keysight DSO1024A
(https://www.wild-pc.co.uk/images/IMG_9285.jpg) (https://www.wild-pc.co.uk/images/IMG_9285.jpg)
2.48ns seems borderline slow for a 200MHz 'scope - I guess it comes in as 0.5/BW and the DSO1024A drops to 500Ms/s when all channels are in use so it probably has a pretty tight filter on the front end.
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Keysight DSO1024A
(https://www.wild-pc.co.uk/images/IMG_9285.jpg) (https://www.wild-pc.co.uk/images/IMG_9285.jpg)
2.48ns seems borderline slow for a 200MHz 'scope - I guess it comes in as 0.5/BW and the DSO1024A drops to 500Ms/s when all channels are in use so it probably has a pretty tight filter on the front end.
Is the scope 50-ohm terminated?
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Keysight DSO1024A
2.48ns seems borderline slow for a 200MHz 'scope - I guess it comes in as 0.5/BW and the DSO1024A drops to 500Ms/s when all channels are in use so it probably has a pretty tight filter on the front end.
Is the scope 50-ohm terminated?
No and I suspect that might have something to do with the response.
Disappointingly though for a 200MHz 'scope the DSO1024A has no built in 50 ohm termination.
However the path from Leo's pulser to the front end is so short that I suspect putting any external termination in will make things worse, not better.
I have a home made 50 ohm pass-through somewhere - I might dig it out and see if my suspicion is correct.
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I have a home made 50 ohm pass-through somewhere - I might dig it out.....
OK, so, makes a huge difference! 1.24ns
Trying to get my head around the interaction of the termination resistance and the input capacitance of the 'scope (18pf, so about 8.8 ohms at a GHz).
(https://www.wild-pc.co.uk/images/IMG_9298.jpg) (https://www.wild-pc.co.uk/images/IMG_9298.jpg)
Fair bit of ringing though, similar with a T piece and the usual crappy 50 ohm terminator.
(https://www.wild-pc.co.uk/images/IMG_9297.jpg) (https://www.wild-pc.co.uk/images/IMG_9297.jpg)
The data sheet gives 1.8ns but that is just a calculated figure (using 0.35/BW)
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hey Leo
Are you thinking the design iterations are pretty much done now?
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hey Leo
Are you thinking the design iterations are pretty much done now?
Hiya,
Pretty much so.
Pulser performance went beyond what I originally wanted it to do. It even has an LED now.
Cheers
Leo
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hey Leo
Are you thinking the design iterations are pretty much done now?
Hiya,
Pretty much so.
Pulser performance went beyond what I originally wanted it to do. It even has an LED now.
Cheers
Leo
right on, I think I am deserving a Christmas present ;)
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It's not that the performance of the BNC connector is unacceptable in itself, it's that the whole idea behind a fast pulser is to test fast hardware. Having to use a BNC-to-SMA adapter with a fast DUT is certainly worse than having to use an SMA-to-BNC adapter with a slower DUT.
I accept your reasoning but I had problems with people not being able to find suitable USB cable locally.
Looks like I'd have to make and stock SMA version as well at some point.
Leo
Has anyone come across any readily available good and cheap SMA(f) - BNC(m) adaptors? (not surplus expensive ones, but cheap when bought new)
The main problem with most of the cheap BNC adaptors and plugs that I've seen is that they are missing the raised flange around the end of the ground connection on the plug, so don't connect well with the socket. The plating on a lot of them does not help much either.
I've sometimes bent the contacts out a little so that they connect better, but that's certainly not ideal.
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Has anyone come across any readily available good and cheap SMA(f) - BNC(m) adaptors? (not surplus expensive ones, but cheap when bought new)
The main problem with most of the cheap BNC adaptors and plugs that I've seen is that they are missing the raised flange around the end of the ground connection on the plug, so don't connect well with the socket. The plating on a lot of them does not help much either.
I've sometimes bent the contacts out a little so that they connect better, but that's certainly not ideal.
I use these https://www.digikey.co.uk/products/en?keywords=314-1184-ND (https://www.digikey.co.uk/products/en?keywords=314-1184-ND) when testing the pulsers.
(http://media.digikey.com/Photos/Mueller%20Photos/MFG_BU-P4290_sml.jpg) (https://www.digikey.co.uk/products/en?keywords=314-1184-ND)
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I would buy another one of these if a SMA version becomes available.
I would guess that most people would still prefer it to be BNC since that makes it a great scope speed testing tool. But with the sort of speeds this thing is going at makes the rated few GHz frequency on a BNC seam a bit lacking. While SMA on the other hand goes in to the low 10s of GHz and is pretty widespread so i'm sure anyone that dabbled with RF has some SMA cables and adapters laying around.
You can probably make the PCB compatible with both SMA and BNC, then just solder BNCs on most of them while leaving a few without connectors. That way you can make small quick runs of the SMA version, but if there is not enough interest you can still go ahead and put BNCs on those too. Guess it would make sense to make the SMA version a few dollars more expensive for the extra trouble.
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I would buy another one of these if a SMA version becomes available.
Same here.
if you make the SMA version available, I will take one too.
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OK Leo, order 23042 in
Thank you and have a good holiday!
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Leo, thank you very much, my order arrived today. :-+ :box:
the Lecroy DDA125 (aka LC684, 1.5GHz analog bandwith) was mentioned in your very first post with 295ps :-//, here are some additional measurements (see attachments):
Channel A: 248 ps
Channel B: 245 ps
Channel C: 249 ps
Channel D: 241 ps
perhaps someone with access could update the list, some more scopes will hopefully follow tomorrow (HP54616B, HM2008,Rigol MSO2202)
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OK Leo, order 23042 in
Thank you and have a good holiday!
Thank you for your order, it has shipped today.
Leo, thank you very much, my order arrived today.
the Lecroy DDA125 (aka LC684, 1.5GHz analog bandwith) was mentioned in your very first post with 295ps :-//, here are some additional measurements (see attachments):
Channel A: 248ps
...
My pleasure! That was the older pulser model based on ADCMP***, its design has changed since then. Amplitude increased too.
Leo
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Hello, Leo,
Order Number is: 23079
Please send the latest version of the design.
Sergey.
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another measurements (see attachments):
HP 54616B (500 MHz): 540 ps :-+
Hameg HM2008 (200 MHz): 1,5 ns :palm:
Rigol MSO2202 (200 MHz): 1,3 ns ;)
cool project, thanks leo! :-+
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cool project, thanks leo! :-+
You are welcome!
Thanks to everyone who ordered one.
All the orders have been shipped - usually within one working day from placing them.
Leo
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The list (https://docs.google.com/spreadsheets/d/1uknvUdL4gNuTyuK7MNAkCj95GFSsDtfgr7nObVppFiE/edit?usp=sharing) has been updated, 94 entries this far.
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The list (https://docs.google.com/spreadsheets/d/1uknvUdL4gNuTyuK7MNAkCj95GFSsDtfgr7nObVppFiE/edit?usp=sharing) has been updated, 94 entries this far.
The DSO1024A entry needs correcting to 1240ps. It turns out that termination does matter after all** :)
** In other news: Pope is Catholic etc.
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Nice work H.O.
For the very fast systems (sampling scopes et al) you might have to note if the pulser is the early or the late version.
I would think that 40ps compared to 50ps Tr will make a difference on a system with a 20ps risetime and such...
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I'm sure it does but I can only put in the list what the user reports here, I unfortunately don't know which user has which version.
I usually have to Google scope sample rate and look at the attached photos/screenshots to figure out if internal/external/no termination has been used. When I don't know I leave that entry blank.
And, as you can see, for the very fast system the formula fails so the list is far from perfect.
I'll fix the DS1204A entry on the next round.
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My TDS3034->3054 hack and THS730A measurements were done terminated at 50 ohms.
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thank you H.O. :-+
all my measurements (DDA125, HP54616B, HM2008 and MSO2202) were done with internal 50 Ohm termination.
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The 100MHz Siglent SDS1104X-E and an upgraded 500MHz Agilent MSO7054A
Very nice compact pulser, as compared to my good old Tektronix 284.
Excelent piece of work Leo !
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Has anyone come across any readily available good and cheap SMA(f) - BNC(m) adaptors? (not surplus expensive ones, but cheap when bought new)
The main problem with most of the cheap BNC adaptors and plugs that I've seen is that they are missing the raised flange around the end of the ground connection on the plug, so don't connect well with the socket. The plating on a lot of them does not help much either.
I've sometimes bent the contacts out a little so that they connect better, but that's certainly not ideal.
I use these https://www.digikey.co.uk/products/en?keywords=314-1184-ND (https://www.digikey.co.uk/products/en?keywords=314-1184-ND) when testing the pulsers.
(http://media.digikey.com/Photos/Mueller%20Photos/MFG_BU-P4290_sml.jpg) (https://www.digikey.co.uk/products/en?keywords=314-1184-ND)
Thanks, but it was more the ones to allow an SMA based pulser to be used on a BNC scope that I was wondering about, and those are the ones that seem harder to do right - however the “You may also be interested in....” bit on the page that you linked to actually led to fairly cheap ones that at least looked OK. I'll need to try some sometime.
I've had so much trouble with cheap connectors that I tend to buy surplus good ones, which are often not too expensive.
One of the good things about the BNC version of the pulser is that it avoids most folk having to mess with these adaptors.
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The discussion about the potential effects of BNC to SMA adaptors got me to wondering if I could see any difference with the IBZ DS800C 4GHz scope that I have.
I hadn't used it much before, and don't normally deal with anything this fast, so it was a bit of a learning curve... With the pulser I was finally able to give it a proper workout.
These are connectors that I used and some prices:
An old surplus Huber+Suhner. No idea of the model, but it looks like RS 716-4779, which is £61.69+VAT.
Emerson VA506. It was from ebay, but is £5.43+VAT from CPC
Cinch 29-3855. It was £2.95+VAT from RS
Also from ebay: “Handy Utility Adapter BNC Female Jack To SMA Male Plug RF Connector Straight EW” #401116160491. £0.99 including post from China.
There are probably a few more (or at least larger) variables involved when using this scope than something like a CSA803, so the rise times are a bit of an estimate. I also only tested one sample of each.
Anyway, the numbers that I came up with for now are:
52ps H+S
53-54ps Cinch 29-3855
54-55ps Emerson VA506
58-60ps ebay 99p
The sheet I got with this pulser gave the measured rise time as 31.8ps
Has anyone tried this with something more stable? This is rather pushing the limits of a scope that is $300 new!
Deliberately moving/loosening the connectors did suggest that there was not really much instability caused by this adaptor - although I would still like to get hold of an SMA version, and something a bit better to test it on.
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The discussion about the potential effects of BNC to SMA adaptors got me to wondering if I could see any difference with the IBZ DS800C 4GHz scope that I have.
I hadn't used it much before, and don't normally deal with anything this fast, so it was a bit of a learning curve... With the pulser I was finally able to give it a proper workout.
...
...
The sheet I got with this pulser gave the measured rise time as 31.8ps
Has anyone tried this with something more stable? This is rather pushing the limits of a scope that is $300 new!
Deliberately moving/loosening the connectors did suggest that there was not really much instability caused by this adaptor - although I would still like to get hold of an SMA version, and something a bit better to test it on.
Thanks for the comparison. It seems even the cheapies are not too shabby.
Screenshots please! As it is a USB scope it should be easier to do than most of us.
The risetimes indicate much better than 4 GHz bandwidth, probably >10 GHz. If the pulser itself really is 31.8 ps, then your scope manages approximately 41 ps. (rise times of source and scope add as root-sum-of-squares). Even using the more conservative conversion factor of 0.45/Tr, you get ~ 11 GHz estimated bandwidth.
I'd be very interested in seeing the shape of the pulse (overshoot, ringing, etc.).
I had never heard of this USB scope before, but I am very interested now.
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Has anyone tried any experiments using this device as a step source for TDR impedance measurements.
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I hope I'm doing this right...Tek 2445
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Has anyone tried any experiments using this device as a step source for TDR impedance measurements.
For fun i did try sticking on a SMA T adapter and put it on my scope. Worked reasonably well. It could tell if a short 15cm coax was close to 50 Ohm. I could also tell the difference between sticking a SMA terminator on the end of a coax directly versus using adapters to go to BNC to N to SMA before going in a terminator. (I think i just wanted to go to BNC and back but didn't find the correct gender BNC to SMA adapter in a hurry but has some N ones laying on the bench)
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from PSPL app note AN3045C:
They use their pulse sharpener to mod the 18 GHz 54754A TDR
to 50 GHz, using a non-TDR 50 GHz 54752A scope plugin. That
means that they must re-implement the coupling to the DUT.
Picosecond Pulse Labs has been bought by TEK, but the app note
is still on the net. The app note is about comparing different TDRs.
The 54750 can use convolution to calculate away its own risetime.
regards, Gerhard
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Thanks for the comparison. It seems even the cheapies are not too shabby.
Screenshots please! As it is a USB scope it should be easier to do than most of us.
The risetimes indicate much better than 4 GHz bandwidth, probably >10 GHz. If the pulser itself really is 31.8 ps, then your scope manages approximately 41 ps. (rise times of source and scope add as root-sum-of-squares). Even using the more conservative conversion factor of 0.45/Tr, you get ~ 11 GHz estimated bandwidth.
I'd be very interested in seeing the shape of the pulse (overshoot, ringing, etc.).
I had never heard of this USB scope before, but I am very interested now.
It was interesting how much the speed went with price, but I suppose that shows the effort that went into getting the performance right. Law of diminishing returns there too!
I've attached a couple of plots. I should start another topic sometime for more plots from it, but too many other things I should be doing at the moment...
There have been some threads related to the DS800, like:
https://www.eevblog.com/forum/testgear/10-ghz-usb-oscilloscope-by-darwin-sabanovic/ (https://www.eevblog.com/forum/testgear/10-ghz-usb-oscilloscope-by-darwin-sabanovic/)
but there's not really that much out there on it.
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Leo,
great job done! Thank you.
Next - my small contribution to the knowledge base.
Lecroy LA354 (Iwatsu TS8500).
Analog-digital;
Bandwidth - 500 MHz;
The resolution of the scanning CCD-matrix: 800x480 pixels;
Waveform Processing - up to 1000000/sec.
In fact, the measured value of RiseTime = 633 ps.
(this does not differ in channels 1 and 2)
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LeCroy WavePro 7300A (release date 2008)
The bandwidth is 3 GHz;
Samplerate - 10/20 GSa/s (realtime), 200GSa/s (equivalent mode, RIS)
In fact, the measured (in RIS mode) value of RiseTime:
1 Channel: 139 ps.
2 Channel: 141 ps.
3 Channel: 141 ps.
4 Channel: 133 ps.
The average is: (139+141+141+133) /4=138.5 [ps]
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Agilent/HP 54845A
The bandwidth is 1.5 GHz;
Samplerate - 4/8 GSa/s (realtime), 500GSa/s (Equivalent Time)
In fact, the measured (in Equivalent Time mode) value of RiseTime:
1 Channel: 223 ps.
2 Channel: 215 ps.
3 Channel: 217 ps.
4 Channel: 200 ps.
The average is: (223+215+217+200) /4 = 214 [ps]
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Agilent DSO81204B in 13GHz enhanced bandwidth mode.
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Agilent DSO81204B in 13GHz enhanced bandwidth mode.
The front is formed by only 4 points. I think it was better to use accumulated sampling (equivalent time mode) here.
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Here (https://docs.google.com/spreadsheets/d/1uknvUdL4gNuTyuK7MNAkCj95GFSsDtfgr7nObVppFiE/edit?usp=sharing), "Calculated scope risetime" is unrealistically optimistic.
In its new generator modules Leo gets the Rise time ~33ps measured with Tek CSA 803A with SD-26. The SD-26 has its own value of Rise time ~17.5ps (according to the specification). This means that the new module has a Rise time of approximately ~28ps (calculated using formula: Risetime Tsystem2 = Tscope2 + Tpulser2)
But for the calculation you are still using 50ps, which leads to large distortions.
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Yes, as I've mentioned before the values "gets out of hand" for the really high bandwidth stuff and as I've also said before there's no way for me to know which version of the pulser the user has and I'm not sure how to handle two different pulser risetimes in the spreadsheet. Say the word and you'll have access to the spreadsheet in order to make it better!
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Yes, as I've mentioned before the values "gets out of hand" for the really high bandwidth stuff and as I've also said before there's no way for me to know which version of the pulser the user has and I'm not sure how to handle two different pulser risetimes in the spreadsheet. Say the word and you'll have access to the spreadsheet in order to make it better!
It would be right that anyone who communicates their measurement results should also report the rise time from the passport of the generator Leo that he received.
Thank you, I appreciate your efforts over the table, and no sense that I should interfere in it.
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Now that i got my 'new' sampling scope working and calibrated i also gave this fast pulser a test.
This is done on a HP 83480A with a 83483A Electrical sampling module(20GHz bw) and the result is 49.8 ps (10% 90%). For the sake of completeness i also included a measurement with 20% 80% rise time. I couldn't figure out how to get a screenshot off the thing using a floppy so i resorted to oldschool CRT photography.
Test report for my pulser (Serial num 4) shows 49.53ps, so that's surprisingly close.
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Welcome to the club! :-)
Above the screen, under STORAGE, the print & setup keys, and their "blue-shifted" versions.
regards, Gerhard
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Welcome to the club! :-)
Above the screen, under STORAGE, the print & setup keys, and their "blue-shifted" versions.
regards, Gerhard
Ah thanks, that worked. What i did before was save trough a different method that made a .pix file that i couldn't find a way to open. The TIFF format looks a bit blury but the GIF is perfect and makes for a nice small file size too. Not auto incrementing the screenshot filename is a bit of a pain tho.
Looking at the photo tells me that my CRT calibration might be a bit out of wack tho. The menus look cream colored in the screenshots while they look more like gray on the actual screen. I prefer the gray look anyway so its the least of my worries. A bit more cornering is the timebase calibration trimm cap that seams like it might be on its way out. It was very touchy during the calibration procedure. If i give it a strong enugh wack on the case where the cap is while running i can see some glitching in the waveform.
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Now that i got my 'new' sampling scope working and calibrated i also gave this fast pulser a test.
This is done on a HP 83480A with a 83483A Electrical sampling module(20GHz bw) and the result is 49.8 ps (10% 90%)...
Test report for my pulser (Serial num 4) shows 49.53ps, so that's surprisingly close.
If you have close results with the Leo device's passport, then your oscilloscope parameters are close to that of Tek SD-26, which Leo applied. That is something about ~18 ps (HP 83480A with a 83483A).
The own rise time of your generator module is about 46.5 ps (probably this is one of the earlier versions).
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If you want a comparison, here is one:
< https://kh6htv.files.wordpress.com/2015/11/an-02e-oscopes.pdf >
There are also older versions, an-02a through d. That guy had ALL the nice toys. ;D
And there is a lot of other good stuff in
< https://kh6htv.com/pspl-app-notes/ >
regards, Gerhard
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Agilent DSO81204B in 13GHz enhanced bandwidth mode.
The front is formed by only 4 points. I think it was better to use accumulated sampling (equivalent time mode) here.
Good call. Here's the results when using ET. It shaves about 8pS off the results.
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Good call. Here's the results when using ET. It shaves about 8pS off the results.
:-+
Now, for calculations it would be nice to know the rise time from Leo's passport for your generator instance.
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Good call. Here's the results when using ET. It shaves about 8pS off the results.
:-+
Now, for calculations it would be nice to know the rise time from Leo's passport for your generator instance.
The rise time on this one was recorded at 33.99pS.
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The rise time on this one was recorded at 33.99pS.
33.99 ps? Okay, we will assume that 34ps.
Then own rise time of your generator is approximately ~29.2ps. And the rise time of your oscilloscope (DSO81204B) is ~33.9ps.
I mean the following:
Tr(sampler) = [Tr2 (obs) - Tr2 (pulser) - Tr2 (jitter) ]1/2
√ (44.762 - 29.22) = √1150.8 = 33.92 ps.
*I ignored the jitter
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I have done a small prototyping run of a version with 2.92mm connector.
Rise time is 30ps±1ps for a 1Vpp pulse as seen by 50? load. Pulses are 10MHz 50% duty negative going (levels are 0V and -1V.)
Test system is CSA803A with SD-30 sampling head (Trt=8.8ps.)
If there is interest I can assemble few more pulsers with 2.92mm or SMA connectors and make them available for sale.
The cost is £99 for 2.92mm connector and £90 for SMA connector version. This will include 18GHz SMA plug-to-plug adaptor like this one (http://uk.farnell.com/amphenol-connex/132168/adaptor-sma-plug-sma-plug-50ohm/dp/1654645) that pulser will be tested with. I have a few 2.92mm adapters and the difference between them and good quality SMA one is really tiny.
Thanks
Leo
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If there is interest I can assemble few more pulsers with 2.92mm or SMA connectors and make them available for sale
I'd take one of the 2.92mm units. That connector looks good, might be interesting to play with it.
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Cool, thank you for your interest.
Fall time is around 25ps at the expense of slightly rougher undershoot.
Leo
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I'd also be interested in a 2.92mm version. Any idea when they would be available ... if you've even decided to go ahead that is?
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I would be interested in buying a SMA version.
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I interested in buying a SMA version.
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Out of curiosity, I connected a pulser to a TAPR TICC through a TADD-2 mini divider to get a 1Hz output and used Lady Heather to analyze the output frequency. My pulser wanders around a 1.05 Hz interval from an average 10,000,001.9 Hz. Attached is a plot and ADEVs of the pulser output. The frequency plot shows the error from the nominal 10 MHz freq. The TICC reference clock was an HP5071 cesium beam oscillator.
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I am interested in an SMA version also.
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Thanks for everyone's interest, guys.
The best way to get one is to place an order online and it will ship in a FIFO manner. I have enough confidence in SMA/2.92mm version to offer it for sale now.
I usually ship immediately but SMA and 2.92mm will take a few days while I am assembling and testing them this week.
2.92mm: http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=302 (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=302)
SMA: http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=303 (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=303)
BNC: http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295 (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295)
Cheers
Leo
I am interested in an SMA version also.
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Got my pulse generator today -very nice quality construction! :D
Two more scopes to add to the list:
Keysight MSOX-4054A: tRISE=664pS, Bandwidth =0.35/664E-12 =527 MHz. Channel 1 is shown. Channels 2-3 were about the same & channel 4 was 550 MHz.
Tektronix 7104 + 7A29 1GHz plugin: tRISE=360pS, Bandwidth =0.35/360E-12 =972MHz. Not bad given the scope hasn't been calibrated in about 5 years.
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I have enough confidence in SMA/2.92mm version to offer it for sale now.
Fast service in more ways than one! :-+
(http://www.ke5fx.com/tds694c.png)
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More curiosity inquiring... the room temperature has been changing a few degrees over 24 hours lately and I measured the tempco of the pulser output freq. Seems to be around 0.2 Hz per degree C.
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The SMA version I ordered, arrived yesterday.
Thank you!
Today I compared all three of your pulse generators on my Keysight 6000X scope.
The serial numbers are:
Pulser# Serial Type RT FT
---------------------------------------------
Pulser-1: P00016, BNC 78.8 ps, 77.9 ps
Pulser-2: P00043, BNC 81.6 ps, 80.9 ps
Pulser-3: P10007, SMA 80.2 ps, 80.8 ps
Interestingly, on the SMA Pulser-3, the waveform has shifted down by 500 mV
More interesting, the very first one you made for me is the fastest right now.
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Interestingly, on the SMA Pulser-3, the waveform has shifted down by 500 mV
More interesting, the very first one you made for me is the fastest right now.
SMA and 2.92mm versions are DC coupled and have negative going pulse.
Try playing with output levels and see if this affects the risetime.
Are you using inter-series adapters?
Cheers
Leo
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I just got mine yesterday and i again got numbers pretty close to the included calibration screenshot on my 20GHz HP sampling scope.
I did take notice that there is an offset now and that the output of the chip looks like it goes directly to the output. Neat wide supply decoupling caps around that chip by the way, im guessing those have lower impedance than regular ones. I don't mind the offset, but if i wanted to get rid of it i can still use a 18GHz DC block that i have somewhere.
By the way since the MCU is running the show is it possible to also have it output lower frequencies now that there is no coupling cap. Haven't found myself needing it but i would imagine some could find it useful for checking long runs of coax cables for damage.
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By the way since the MCU is running the show is it possible to also have it output lower frequencies now that there is no coupling cap. Haven't found myself needing it but i would imagine some could find it useful for checking long runs of coax cables for damage.
Pulse train is still taken directly from TCXO. I might design a variable pulse length version at some point but it is not too trivial as I'd like to maintain low jitter for those of us who use sampling scopes. Low as in no more than a few picoseconds.
Leo
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as I'd like to maintain low jitter for those of us who use sampling scopes. Low as in no more than a few picoseconds.
Leo
Fully agree here considering the way I use it.
Got your first version and I was quite impressed about that point about the trigger reliability and consistent timing.
Cheers :)
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Ah that's for the best then.
For fault finding coax cables you probably don't need a pulse that sharp anyway.
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Siglent SDS-1202X-E
With a HP 10100C 50 ohm terminator and without terminator.
Rigol DS1074Z (100 MHz)
With terminator and without terminator
Playing with this I noticed something really odd in the Rigol scope. When it allows the operator to enable or disable the sin(x)/x interpolation it does affect the dots display, not just the vector display, which is wrong as far as I know. The dots display is supposed to show just samples. Or should be, right?
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Playing with this I noticed something really odd in the Rigol scope. When it allows the operator to enable or disable the sin(x)/x interpolation it does affect the dots display, not just the vector display, which is wrong as far as I know. The dots display is supposed to show just samples. Or should be, right?
Yes, should be just sample points.
rf-loop has mentioned this a few times and using his login in 'By user' for a search and 'fake dots' will find his posts about this.
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I finally got round to testing a BNC-equipped unit received from Leo on 1/23/18.
By request, this unit was set up for 1.0Vpp output. Leo noted on its included docs that rise time at this high output amplitude is degraded to ~60 ps. However I also noticed from the included test plot that, as an apparent side effect, aberrations in the first ns appear to be well under 2% p-p with this setup. Leo's CSA803 showed very nearly a perfect step.
Many appear obsessed only with rise time; in my experience, a clean top without overshoot is critical for the risetime to be quantitatively meaningful. A dead flat top is an extremely rare and valuable property in a sub-100ps signal source.
I checked it for myself with a Tek S6 sampling head in a 7S11/7T11/7904 rig, approximately confirming both the reported rise time and measured flatness. I count about 65 ps intrinsic after RSS regressing the nominal S6 response, and about 3% p-p aberration in the first 250 ps. (I suspect my SMA terminator of some mischief at about 300ps; the S6 loops the signal back out to an external termination, to allow for TDR applications.)
First 3 attachments show the rise at 50, 200 and 1000 ps/div. Fourth photo shows the fall, significantly faster at about 40 ps (after RSS regression), but including about 7% p-p aberration.
For kicks, the fifth shot is an S-52 tunnel diode (25 ps), and sixth is a home-brew pulser using a Russian GI308D tunnel diode (about 75 ps).
Bottom line: With 1Vp-p amplitude, this unit gives ~60 ps rise with damned near perfect shape, and ~40 ps fall with a little aberration. Win-win. Many thanks, Leo!
-Mike
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rf-loop has mentioned this a few times and using his login in 'By user' for a search and 'fake dots' will find his posts about this.
Yep, I noticed. You get to choose between fake dots or fake warranty when choosing a cheap scope.
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I forgot, @Leo Bodnar
Any plans to release the USB command set so that anyone can write a control program? I am not a Windows user and being able to access it from a Python program would be really useful!
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Some screen shots from my DSOs
GW Instek GDS-2702E V 1.24 FW
GW Instek MSO-2204EA V 1.32 FW
Rigol DS1102E V 0.4.2 SP1 FW
Pulser set as shipped by Leo. All the scopes meet the specs by a reasonable margin. The 2072E is considerably more than 70 Mhz, but I don't like the top on either of the Insteks.
I can't say how much I appreciate that Leo sells these. Having attempted to build one 25 years ago and failed miserably, I have a certain appreciation for the problems such things pose. My sole, very minor, grumble is I would like to have had a cover over the SMD parts to protect them from damage. I was going to install a small metal plate using longer screws, but they appear to be staked in place. But I'll make a U shape clip and epoxy it in place instead.
It would certainly be nice to have the ability to change the frequency of the square wave, but I've got an old scope time base calibrator which accepts an external reference and one of Leo's GPSDOs, so not really needed. Besides which, the GPSDO will do the job as is.
All the screenshots were made with a 50 ohm terminator and a tee as I don't have a 50 ohm thru terminator. I had one I'd made, but I stripped it for the Pomona box I'd built in. And for this sort of task I wouldn't have trusted it anyway.
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Earlier I posted a plot of the pulser output frequency and ADEVs. The freq is with a couple of Hz... good enough to calibrate most scopes considering they usually have crappy time base oscillators.
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Here are some waveforms from a Tek784D. The overshoot on the longer timescale trace isn't real but a result of the slow sampling at that sweep speed. Note how flat the pulse is. Nice for step testing.
The 784 is rated at 1 Ghz giving an implied risetime of 350ps....easily met. Thanks Leo for a great product. I've built many "fast" pulsers in my time, most much slower than his but at higher output voltage. This unit is really nice for testing my scopes.
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1GHz is 35 ps, not 350 ps :D
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1GHz is 35 ps, not 350 ps :D
Must be those newfangled metric picoseconds. :)
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1GHz is 35 ps, not 350 ps :D
lol...I wish...Formula is 1/f x .35 or 1Ghz = 350ps. Look it up at Tektronix.
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Must be those newfangled metric picoseconds. :)
Nope, Chineseium picoseconds.
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1GHz is 35 ps, not 350 ps :D
Must be those newfangled metric picoseconds. :)
That's 4 61/508" divided by the speed of light*, for you colonial types. :)
* 14,238,992,130,000 inches per milli-fortnight.
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* 14,238,992,130,000 inches per milli-fortnight.
I once worked for a company that required each project to have a zillion different pieces of documentation that nobody ever read. I wrote one spec where all the timings were in units of ffn... femto-fortnights. It was three years before anybody noticed and asked what a ffn was.
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Oops, not well awaken yesterday morning, sorry |O
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Oops, not well awaken yesterday morning, sorry |O
It's ok...we all have those moments....more often as we get older it seems...
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* 14,238,992,130,000 inches per milli-fortnight.
I once worked for a company that required each project to have a zillion different pieces of documentation that nobody ever read. I wrote one spec where all the timings were in units of ffn... femto-fortnights. It was three years before anybody noticed and asked what a ffn was.
Hah nice one.
But did you specify weather you used the imperial or metric fortnight? Oh and does it also take in account leap seconds or the earth slowing down overtime?
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I'm a little nervous about damage either mechanical or ESD. I had thought to put a small metal plate on the back, but the screws appear to be staked down.
I'm contemplating a U shaped piece of aluminum with a U cutout for the BNC and then securing it with epoxy on both sides. However, I don't see a good way to ground it. I don't know if grounding it is good or bad.
Leo? Anyone else?
Edit: I got a piece of heatshrink big enough to get the pulser in. I cut Xs for the connectors (2nd try) and it went well. Photos attached.
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Reading through this thread makes me envious of some of the scopes shown here :-+
Here are the results for the RTB2004 (100 MHz) with a 50 ohm pass through terminator.
According to the R&S specsheet the 100MHz model should have a rise time of <3.5ns
Measured average rise time for the 100 MHz model is 1.85ns which calculates to a bandwidth of 189 MHz.
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I got my LB generator last night am I'm very satisfied with it. :-+
To protect the SMD componets I printed a small housing for it and uploaded the STL file here:
https://www.eevblog.com/forum/testgear/gw-instek-mdo-2000e/msg1458487/#msg1458487 (https://www.eevblog.com/forum/testgear/gw-instek-mdo-2000e/msg1458487/#msg1458487)
My GW Instek MDO-2204EX has 1,22ns rise and fall time. Plenty fast for the work I do. :-/O
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I measured a Keysight DSOX3014T we have at work today.
It is 2,90ns comparable to 120MHz analog bandwidth.
The specification is 100MHz.
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I just measured my newly arrived MSOX3104T purchased from Keysight "slightly used" via the webstore. This came with fresh cal, all accessories and a 3 year warranty. It was *not* cheap.
Measured rise time is 436 pS which works out to 802.7 MHz :-(
I went to the datasheet and checked. The spec is 1 GHz and rise time of <450 pS. The 500 MHz version has a 700 pS risetime listed. I'm deeply disappointed in Keysight fudging a specification like that. It doesn't really matter for what I expect to do.
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Leo, are you planning on another batch of the ones with BNC connector? If not I'll definitely be getting one of the SMA's, but I'd prefer the BNC. Thanks in adv.
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I just measured my newly arrived MSOX3104T purchased from Keysight "slightly used" via the webstore. This came with fresh cal, all accessories and a 3 year warranty. It was *not* cheap.
Measured rise time is 436 pS which works out to 802.7 MHz :-(
I went to the datasheet and checked. The spec is 1 GHz and rise time of <450 pS. The 500 MHz version has a 700 pS risetime listed. I'm deeply disappointed in Keysight fudging a specification like that. It doesn't really matter for what I expect to do.
Well, 436 ps is less than the guaranteed 450 ps.
The 1 GHz spec is measured with a leveled signal generator and means that the displayed trace is less than 3 db down from the actual level at 1 GHz.
The formula that rise time (in ps) = 0.35 * bandwidth (in MHz) is not necessarily valid for modern scopes as it depends on the anti-aliasing filter used.
High end scopes even have selectable filters depending on the desired use case.
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Yeah, that 0.35 * Tr equation is only a general guideline. It has a lot of assumptions baked into it that won't necessarily apply to a specific instrument. As long as it meets the stated specs, you're fine.
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Well, 436 ps is less than the guaranteed 450 ps.
The 1 GHz spec is measured with a leveled signal generator and means that the displayed trace is less than 3 db down from the actual level at 1 GHz.
The formula that rise time (in ps) = 0.35 * bandwidth (in MHz) is not necessarily valid for modern scopes as it depends on the anti-aliasing filter used.
High end scopes even have selectable filters depending on the desired use case.
Absolutely right.
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Hey Gerry,
I will make another batch of BNC ones this week and will drop you a PM.
Cheers
Leo
Leo, are you planning on another batch of the ones with BNC connector? If not I'll definitely be getting one of the SMA's, but I'd prefer the BNC. Thanks in adv.
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I just measured my newly arrived MSOX3104T purchased from Keysight "slightly used" via the webstore. This came with fresh cal, all accessories and a 3 year warranty. It was *not* cheap.
Measured rise time is 436 pS which works out to 802.7 MHz :-(
I went to the datasheet and checked. The spec is 1 GHz and rise time of <450 pS. The 500 MHz version has a 700 pS risetime listed. I'm deeply disappointed in Keysight fudging a specification like that. It doesn't really matter for what I expect to do.
Don't be disappointed, your figure of 436ps is about the same, as what I measured on my MSOX3104A
Mean: 422 ps
Min: 400 ps
Max: 450 ps
StdDev: 9.37 ps
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I'm not at *all* unhappy with the instrument. It's *really* nice. I'm unhappy with marketing. The rise time is specified as "calculated" in the datasheet and the conventional 0.35/BW rise time is listed. But rather clearly the MSOX3104 rise time specification is measured. Were it calculated, it would be <350 pS.
Using my out of cal 8648C at -20 dBm it appears to be down about 2 dB at 1 GHz. I've got a 438A with 8481D and 8482A heads which have fresh cals with data, so I'll know more once I retrieve the cal data from Keysight and start testing everything I have against everything else I have.
I had planned on selling my Instek MSO2204EA, but I may reconsider as it will do much longer FFTs. That decision will take some study as I have an 8560A with TG. So I need to come up with some torture tests.
I always have found the 0.35/RT bit rather suspect as it makes a lot of assumptions about the rate at which the BW falls off.
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I'm not at *all* unhappy with the instrument. It's *really* nice. I'm unhappy with marketing. The rise time is specified as "calculated" in the datasheet and the conventional 0.35/BW rise time is listed. But rather clearly the MSOX3104 rise time specification is measured. Were it calculated, it would be <350 pS.
The 0.35/BW rise time equation is a loose approximation that's based on a specific filter response, which itself is a tradeoff between edge fidelity and raw 3-dB bandwidth. Not all scopes are purely Gaussian.
(https://i.imgur.com/OAqXcWQ.png)
(from http://literature.cdn.keysight.com/litweb/pdf/5988-8008EN.pdf (http://literature.cdn.keysight.com/litweb/pdf/5988-8008EN.pdf))
You're fine. Nobody is trying to put one over on you. :)
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I'm not at *all* unhappy with the instrument. It's *really* nice. I'm unhappy with marketing. The rise time is specified as "calculated" in the datasheet and the conventional 0.35/BW rise time is listed. But rather clearly the MSOX3104 rise time specification is measured. Were it calculated, it would be <350 pS.
The 0.35/BW rise time equation is a loose approximation that's based on a specific filter response, which itself is a tradeoff between edge fidelity and raw 3-dB bandwidth. Not all scopes are purely Gaussian.
(https://i.imgur.com/OAqXcWQ.png)
(from http://literature.cdn.keysight.com/litweb/pdf/5988-8008EN.pdf (http://literature.cdn.keysight.com/litweb/pdf/5988-8008EN.pdf))
You're fine. Nobody is trying to put one over on you. :)
I'd prefer the Gaussian step response. But I've not observed that to be an option except for R&S. I can't see any reason that you could not let the user choose the step response.
My complaint is changing the method of calculation of rise time between models in the same line of instruments. It's a matter of integrity, not the performance of the instrument that bothers me. The closest analogy I can think of is finding out your wife of 20 years is cheating on you.
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My complaint is changing the method of calculation of rise time between models in the same line of instruments. It's a matter of integrity, not the performance of the instrument that bothers me. The closest analogy I can think of is finding out your wife of 20 years is cheating on you.
I imagine most people would prefer the familiar Gaussian response, given a choice. The decision probably comes down to the Nyquist frequency margin associated with the achievable sampling rate. If you're building the fastest possible scope with a given technology, you are probably not oversampling by the 5x or more that we'd all prefer. You may be cutting things as close as 3x. The Gaussian filter falls off so slowly that aliasing is objectionable at 3x, so the faster scopes in a given family may be more likely to incorporate flat-response filters than the slower ones.
Figure 1 in the Keysight app note is a good illustration of this problem, although of course the marketing folks don't spin it that way:
(https://i.imgur.com/zwT9TZ5.png)
They are assuming a 4 GHz clock in that figure. If they could sample at 5 GHz or higher, they would presumably have used an industry-standard Gaussian filter. The usual 0.35/BW rule of thumb would have applied, and nobody would have complained about questionable risetime specs or overshoot on fast pulses. But marketing tells engineering, "Yeah, I'm gonna need you to come in on Sunday and push this chipset to 1 GHz," and this is the resulting compromise.
I can't see any reason that you could not let the user choose the step response.
Keep in mind that we're talking about the antialiasing filter in front of the ADC, not a set of coefficients. Allowing the user to switch between two different antialiasing filters would be quite expensive, and it would impress maybe 1% of the customer base.
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I think that's a fair rendition. My complaint really is changing the calculation for the last scope in the datasheet.
The MSOX3000T has only a single reduced bandwidth option, 20 MHz. My MSO2204EA will let me choose 20, 100 or 200 MHz. There's no reason you couldn't do a digital filter to give the user a Gaussian step response. It would cost some bandwidth, but so what?
I don't like the "flat as far as we can push it" model. I was quite stunned to see 7% overshoot. God only knows how you'd diagnose overshoot in a DUT.
My major project is to implement FOSS FW for Zynq based DSOs. I was all set to start serious work on that when watching my brother in-law rapidly deteriorate from Parkinson's convinced me I should spend some money on test gear I have always wanted. That led to a major reorganization project.
I was actually browsing eBay for older gear and seriously considering an 8104A, but the 6 fans on the side and the physical dimensions scared me off. Then I found a 1/2 price deal from Keysight that included probes, fresh cal with data and a 3 year warranty. I'm afraid I succumbed to bargain fever.
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I think that's a fair rendition. My complaint really is changing the calculation for the last scope in the datasheet.
The MSOX3000T has only a single reduced bandwidth option, 20 MHz. My MSO2204EA will let me choose 20, 100 or 200 MHz. There's no reason you couldn't do a digital filter to give the user a Gaussian step response. It would cost some bandwidth, but so what?
The marketing department will -- justifiably -- scream bloody murder at that. Why? Because for better or worse -- usually worse -- bandwidth is what people buy. If they didn't use the flat-response filter, they (presumably) couldn't have offered a 1 GHz scope in the MSOX3000 lineup. They would have lost sales to competitors who had no such compunctions. Most users will be fine with this decision, but as you note, it is something you need to be aware of when looking at rise time and overshoot.
A post-acquisition filter option might cost more than just bandwidth. It would have to run at the fastest sample rate supported by the acquisition hardware, so it might not be feasible to do it in realtime, especially given their ASIC-oriented block diagram. And it would require some further hand-waving to explain on the spec sheet.
That's not to say this sort of thing can't be done -- some scopes rely on frequency-domain correction to deliver their bandwidth specs, in fact, even to the extent of performing the necessary filtering in 'screenspace,' which is an especially ugly hack. I wouldn't criticize the Keysight guys for not doing stuff like that in this particular model line.
Besides, now that you know what the impulse response looks like, you can deconvolve it by eye. :)
I don't like the "flat as far as we can push it" model. I was quite stunned to see 7% overshoot. God only knows how you'd diagnose overshoot in a DUT. My major project is to implement FOSS FW for Zynq based DSOs. I was all set to start serious work on that when watching my brother in-law rapidly deteriorate from Parkinson's convinced me I should spend some money on test gear I have always wanted. That led to a major reorganization project. I was actually browsing eBay for older gear and seriously considering an 8104A, but the 6 fans on the side and the physical dimensions scared me off. Then I found a 1/2 price deal from Keysight that included probes, fresh cal with data and a 3 year warranty. I'm afraid I succumbed to bargain fever.
We've all been there, that's for sure. Nothing wrong with a brand-new MSOX3000T at half price!
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I think that's a fair rendition. My complaint really is changing the calculation for the last scope in the datasheet.
The MSOX3000T has only a single reduced bandwidth option, 20 MHz. My MSO2204EA will let me choose 20, 100 or 200 MHz. There's no reason you couldn't do a digital filter to give the user a Gaussian step response. It would cost some bandwidth, but so what?
I don't like the "flat as far as we can push it" model. I was quite stunned to see 7% overshoot. God only knows how you'd diagnose overshoot in a DUT.
My major project is to implement FOSS FW for Zynq based DSOs. I was all set to start serious work on that when watching my brother in-law rapidly deteriorate from Parkinson's convinced me I should spend some money on test gear I have always wanted. That led to a major reorganization project.
I was actually browsing eBay for older gear and seriously considering an 8104A, but the 6 fans on the side and the physical dimensions scared me off. Then I found a 1/2 price deal from Keysight that included probes, fresh cal with data and a 3 year warranty. I'm afraid I succumbed to bargain fever.
The 20MHz bandwidth is usually a analog feature in the front end. But i have seen some scopes offer adjustable digital filtering options where you can set any frequency you want within reason. Often this seams to be done afterwards in software tho.
When doing a important measurement one should avoid working close to the scopes bandwidth specs anyway. You might see the signal but you don't know whats hiding beyond what you can see and what might be attenuated without your knowledge. This is the main reason why its nice to have a scope faster than 100 MHz, but it unfortunately costs a pretty penny to get lots of bandwidth.
You did the right thing going for the MSOX3000T. For day to day use these MegaZoom ASIC scopes are a great choice. I have a MSO9000 Infiniium scope and while packed with a ton of features and performance, but its not a good daily driver. Its huge, its loud, its slow, you have to dig trough menus to set stuff up. This is a scope you use when you need to make more serious measurements, rather than just checking if your clock is moving on a board. You use such a scope when you want to make a eye diagram of a high speed line and you spend time to carefully tap into the circuit with a active probe, calibrate the probes for skew, set up the scope to do clock recovery in the waveform etc.
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Berni’s right regarding the 3000T vs the 8104A as a daily driver.
As well as a 3000A, I have the forerunner of the 8104A, the 54832D (which, if you upgrade the motherboard, thinks it’s an 8104A). The 3000A is far easier to use for 99% of tasks.
My only slight difference of opinion to Berni is that I’ve found I really like the big screen format of the 7104B, and so that tends to be the goto scope for me. In my setup, none of the scopes take up any bench space, they are raised above it by various means. The UI of the 5/6/7000 series is the forerunner to the 3000 series, and despite being Vxworks rather than Windows CE, in practice it’s almost identical. That’s unlike the 54832D or 8104A which has many of the functions accessible only from menus in the Windows UI.
You can never have enough scopes, it’s not at all uncommon to be running two scopes when you’re probing two different trigger domains, and even three sometimes, particularly if you’re monitoring some real time serial bus diagnostic information.
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=440248;image)
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You can never have enough scopes
Is 50 scopes too many? :-// I could prune a few if it is...
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That's a nice digital scope collection you got there.
My daily driver scope is a Agilent MSO6034A and i really appreciate its UI speed. I always wanted a MSO7000 series scope for its large screen, but i could never find one for a good price.
From all the scopes on the market i still think the MSO7000 is the best one for a quick probe around. Its got the features and speed (okay not quite 1M waveforms but who cares) of the MSOX3000 but has faster boot times, higher resolution and larger display, more sample memory etc.
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Sometimes I do think, I have too many scopes but somehow they are all used.
I would not use my 1GHz MSOX3104A if I need to measure anything close to the upper BW limit.
For that I use the 6 GHz 6000X series scope.
But the one scope that I find most convenient to use is the 7000 series one. I have two of them and they are just very pleasing, not just for the large screen and fast response to any key input, they are in my opinion almost perfect scopes. And once in a while they are offered at really low cost on ebay.
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Sometimes I do think, I have too many scopes but somehow they are all used.
I would not use my 1GHz MSOX3104A if I need to measure anything close to the upper BW limit.
For that I use the 6 GHz 6000X series scope.
But the one scope that I find most convenient to use is the 7000 series one. I have two of them and they are just very pleasing, not just for the large screen and fast response to any key input, they are in my opinion almost perfect scopes. And once in a while they are offered at really low cost on ebay.
I agree. I find the 7000 UI to be slightly more responsive compared to the 3000A, that might be another reason why I use it more than the 3000A. The 7000 boots more quickly. Both of these are probably due to the use of VxWorks in the 7000 compared to Windows CE in the 3000.
One further thing, the 7000B has a few more buttons and knobs compared to the 5000, 6000 and 7000A, it’s more similar to the 3000 in that respect, but the control layout between the 3000A and the 7000B is frustratingly slightly different which is a minor irritation.
There are a few extra bits of functionality on the 3000A that I like, but equally the 7000B has one or two things that the 3000A doesn’t such as optional equivalent time sampling which can be useful on high speed stuff.
The 1Mwfm/s of the 3000 frankly for me is very rarely of any benefit compared to the 100kwfm/s of the 7000. I’d rather have the deeper memory that the 7000 offers. The 3000 offers runt triggering but not the 7000, but then it’s incredibly rare I ever use that functionality. Nice to have, sure, but not at the top of my requirements.
My main criticism of both in my use cases is that neither decode faster than about 30MHz SPI.
Overall though it’s the Megazoom together with the super responsive UI that makes these scopes so useable on a day to day basis, and I can live with the relatively limited memory depth that it dictates.
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Yeah the 1M waveforms per second is pretty much the same as 100K. As long as its not 0.5K like some of the old scopes.
The button layout diference from the 5000/6000/7000 to the X2000/X3000 does annoy me as well. At work we have a MSOX3000 and i keep on hunting around the wrong corner of the scope for the button, hovering my finger around the front panel while feeling like im blind before realizing its not in that area.
The MSO9000 front panel also has some neat buttons i wish i had on my MSO6000. The trigger channel, slope, auto/manual are all dedicated buttons and i use them all the time, they even include dedicated LEDs next to them to show the current state of that setting, love it. But then its missing some useful buttons for other stuff i use all the time (Like aquisition mode and display settings).
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BNC: http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295 (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295)
How does one get on the Waitlist for new BNC options?
The website says "sold out"; but no link for a Waitlist.
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Putting an optional Gaussian filter on the waveform via an ASIC is *not* hard. Marketing gets their "1 GHz" spec and the user gets a sensible step response when they need one. I'm hoping that user defined digital filters are an option.
I'm comfortable with my choice. I've been rewiring my bench so I haven't given it a full work out, but so far it has been very pleasant to use just playing around. I'm a retired research geophysicist, so this was a stretch to justify. But after buying a bunch of 90's HP gear, I got *really* tired of Chinese stuff. So I bought a 33622A from the Keysight eBay store to replace my F***Tech FY6600 which borked itself the day after i fixed the 176 Vpp AC on the BNC grounds. I had the misfortune to get one with the V3.0 FW. Lots of promises of a fix from F***Tech, but nothing actually done.
I certainly can deconvolve it, but I wouldn't try doing it by eye.
As for BNC pulsers, Leo is making a new batch. Email him. He's *very* responsive. But not website obsessed.
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Putting an optional Gaussian filter on the waveform via an ASIC is *not* hard. Marketing gets their "1 GHz" spec and the user gets a sensible step response when they need one. I'm hoping that user defined digital filters are an option.
I'm comfortable with my choice. I've been rewiring my bench so I haven't given it a full work out, but so far it has been very pleasant to use just playing around. I'm a retired research geophysicist, so this was a stretch to justify. But after buying a bunch of 90's HP gear, I got *really* tired of Chinese stuff. So I bought a 33622A from the Keysight eBay store to replace my F***Tech FY6600 which borked itself the day after i fixed the 176 Vpp AC on the BNC grounds. I had the misfortune to get one with the V3.0 FW. Lots of promises of a fix from F***Tech, but nothing actually done.
I certainly can deconvolve it, but I wouldn't try doing it by eye.
As for BNC pulsers, Leo is making a new batch. Email him. He's *very* responsive. But not website obsessed.
Well the issue is that scopes do this in the analog domain. Historically it was simply how fast the analog front end could go. It was difficult and expensive to make a 1GHz scope AFE so lower end models had cheaper ones that didn't go as fast. These days its not nearly as hard to do anymore but the scope manufacturers still want to sell 100MHz scopes to the ones who cant afford to pay more for a scope while still getting the money out of the big costumers who need the 1GHz. Same reason why the iPhone comes with various amounts of flash and becomes very expensive towards the higher end. Filtering the waveform digitally is noticeable by the user because the ADC starts to look better than it actually is. So as a result the new Keysight S series scopes have a AFE ASIC that has built in switchable filters to make the scope be a 500MHz or a 8GHz scope. It sucks being sold a license for something you already have but i do understand Keysight needs to make money on this so i can't really blame them for it.
That being said when they do provide digital filtering in the acquisition ASIC its actually very useful. I have a Agilent DSO9000 scope and they have decided to implement this as "High resolution mode", unlike the MegaZoom ASIC scopes here this simply puts ADC samples trough a digital low pass filter. Depending if you select 9bit 10bit 11bit or 12bit mode you get different low pass cutoffs (For a while they tried to sell this as a 10bit scope as a knee jerk reaction to LeCroys 10bit stuff). Because the ADC is a speedy 20GS/s means it gives it a lot of data points to work with and this brings the so called "12bit mode" with 500MHz of bandwidth. That's still plenty of bandwidth for most work, however the low pass filtering really cleans up the ADC noise a lot. Even on 10mV/div you get a nice sharp line on the screen rather than a big fuzzy band, but you don't get any of the funky effects that High Res mode does on Agilents MegaZoom scopes. It simply makes the scope act like its 500MHz but with a really low noise ADC.
So id love to see this done in more scopes. But there is a catch. The penny pinching 100MHz costumers get superbly low noise scope, but when the big fish 1GHz costumer comes along he will get the usual noise on his scope as there has to be no filtering to be able to reach 1GHz. This makes the 1GHz model seam like its not as good as the rest of the series might have you expect. Some of the specs are also going to look worse in the datasheet for the 1GHz model. So i don't think scope manufacturers are all that motivated to do this.
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Why do you think that the BW filtering has to be implemented in the AFE? You have to anti-alias in the analog domain. But it doesn't make economic sense to implement a separate analog filter for each sample rate. The initial sampling is done at the maximum rate and then subsampled with digital anti-alias filters for lower sample rates.
I don't know what's in the Keysight MSOX ASIC, but I do know what's in the Instek MSO. That's a Zynq 7010. And there are definitely not a large number of analog filters in the front end of the Instek 2000E line. That's just a set of attenuators and buffering for the ADC input. My MSO2204EA offers 200 MHz, 100 MHz and 20 MHz BWs.
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I looked into it again and sorry it seams i was wrong about the S series.
The S series does make use of all digital filtering to limit bandwidth. They talk about easy bandwidth upgrades when talking about the fancy new analog front end ASIC, but looking at the specs in detail the ASIC only has 20MHz and 200MHz analog filters inside it.
As a result the lower bandwidth units have significantly lower noise floors. At 1V/div the 500MHz model gets 5 mVrms of noise while the 8GHz model gets 24.1 mVrms. So yes the lower bandwidth models are simply locked into using that "DSP high resolution mode" permanently, only the 8GHz model allowing you to turn it off completely.
The X2000 and X3000 are not up gradable in the same way to take the lowest bandwidth model and turn it into the highest bendwith one so the analog front ends are different between some models.
I went and had a try at what this high resolution filter does on a signal from this picosecond pulse generator and here is what i got in "12 bit" mode where the bandwith is supposed to be 500MHz. There is a little bit of overshoot visible but its not nearly as drastic as in the example from KE5FX
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auto/manual are all dedicated buttons and i use them all the time
Yes, auto/manual trigger really should have its own dedicated button. The 3000 you can assign trigger mode to the Quick Action key, but that’s not an available option on the 7000. Even the 54832D has a dedicated trigger mode button.
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That's a pretty respectable step response. Attached is the MSOX3104T response to my pulser which Leo measured at 36 pS. I'm not concerned about the actual rise time, but I'm not happy about the overshoot. How would you ever use it to check for ringing on a DUT line?
As for SW upgrading the X3000T BW you certainly can.
https://www.keysight.com/en/pdx-x202185-pn-MSOX3034T/mixed-signal-oscilloscope-350-mhz-4-analog-plus-16-digital-channels?pm=upg&nid=-32541.1150362&cc=US&lc=eng (https://www.keysight.com/en/pdx-x202185-pn-MSOX3034T/mixed-signal-oscilloscope-350-mhz-4-analog-plus-16-digital-channels?pm=upg&nid=-32541.1150362&cc=US&lc=eng)
So why they don't allow the user to select 100, 200, 350 or 500 MHz BW on a scope licensed for 1 GHz is beyond me.
Edit: I just spoke with Keysight support. The math functions give me a low pass filter option. It doesn't work at all at 500 pS/Div, but does at 1 nS/Div. Interestingly if I apply a 1 GHz low pass filter I get ~1% overshoot and a 520 pS rise time.
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Yep the auto/manual trigger mode button is very useful. Then again at least these scopes have very little in the way of completely useless buttons, some could be buried in menus to make room for more useful ones tho.
And yes you can upgrade the bandwidth on the X3000 series but not all the way. It appears they make 3 flavors of the scope mainboard:
-Low: 100Mhz and 200MHz
-Mid : 350MHz and 500MHz
-High: 1GHz
So the analog front end might have two bandwidth modes to select between much like the ever popular Rigol 1000Z series (I think they use a varicap or PIN diode or something to switch it). But yes they surely could expose this trough software I could see it useful being able to switch a scope between 100 and 200 MHz.
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That's what I got with the LeCroy SDA 6000. I used a homemade adapter for the Leo BNC-connector, so it could have a little effect on the result. Nevertheless, this result is in line with the LeCroy specification (<75 ps), if you take into account your own Rise time of the signal source - about 30 ps.
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Is this still available? I would like to get one so I can do a high frequency response cal on a Tek 485 my self.
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Is this still available? I would like to get one so I can do a high frequency response cal on a Tek 485 my self.
http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295 (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295)
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Is this still available? I would like to get one so I can do a high frequency response cal on a Tek 485 my self.
We are making a new batch of BNC ones, they should be back in the shop in one-two weeks (mid-August.)
Thanks
Leo
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So why they don't allow the user to select 100, 200, 350 or 500 MHz BW on a scope licensed for 1 GHz is beyond me.
100% agree - especially on units with many bandwidth steps available in the same hardware (e.g. my R&S unit has 70, 100 and 200 MHz options below the 300 mine is licensed for) the system is calibrated for the other steps and the analogue or digital filter is already waiting to be used. If I have a 50MHz bandwidth signal I'd love to be able to see it without all the other 250MHz worth of noise I don't need (and sometimes aberrations - e.g. a probe specced at 50MHz may not simply roll off afterwards, it could have some nasty peaks above the rated frequency).
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The 40ps BNC pulsers are back in stock and ready for immediate shipment.
Get yours here http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295 (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295) while they are in.
The design has matured very nicely - it is repeatable, robust, and has awesome performance for the price - so don't wait if you wanted one.
If you are worried about the bleeding edge, don't - it just works.
Cheers for all your support and good discussions!
Leo
Here are typical shots of what current units are:
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Just a heads-up for anyone who has missed this - BNC versions are in stock for immediate shipment.
I have modified a few units to take external trigger input instead of on-board TCXO. This allows feeding external LVCMOS (1.0v to 3.3v) trigger input into SMA connector. Trigger frequency can be from 1MHz to about 200MHz.
Thanks
Leo
http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295 (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295)
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Just a heads-up for anyone who has missed this - BNC versions are in stock for immediate shipment.
I have modified a few units to take external trigger input instead of on-board TCXO. This allows feeding external LVCMOS (1.0v to 3.3v) trigger input into SMA connector. Trigger frequency can be from 1MHz to about 200MHz.
Thanks
Leo
http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295 (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295)
Leo - have you seen the Picotest product? They are selling a USB powered pulse gen for $3,500!!!
https://www.picotest.com/products_J2151A.html (https://www.picotest.com/products_J2151A.html)
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rx8pilot: unfortunately $98 for shipping to EU country ?!
Is anybody willing to buy two units for me and send them private to me?
Karsten
Gesendet von iPhone mit Tapatalk
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Leo - have you seen the Picotest product? They are selling a USB powered pulse gen for $3,500!!!
https://www.picotest.com/products_J2151A.html (https://www.picotest.com/products_J2151A.html)
Wow it might even be a similar design because the specs look pretty close to Leos pulse generator.
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Press Release (https://www.picotest.com/downloads/INJECTORS/Picotest%20Releases%20New%20PerfectPulse%20Signal%20Generator%20TDR_REV1_072618.pdf)
Contact Information: Picotest.com Steve Sandler - Steve@picotest.com (877) 914-7426
June 6, 2018 Phoenix, AZ: Picotest.com, a leader in high resolution test and measurement equipment, has released a new, low cost, pocket-sized, fast edge signal generator and TDR in one convenient package. “Such a high speed, precise TDR/TDT has never before been available in this portable form, requiring only a USB power source, and at this price point,” according to Steve Sandler, Picotest CEO.
What can you say? "At this price point" is technically correct.
Leo - have you seen the Picotest product? They are selling a USB powered pulse gen for $3,500!!!
https://www.picotest.com/products_J2151A.html (https://www.picotest.com/products_J2151A.html)
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Just a heads-up for anyone who has missed this - BNC versions are in stock for immediate shipment.
I have modified a few units to take external trigger input instead of on-board TCXO. This allows feeding external LVCMOS (1.0v to 3.3v) trigger input into SMA connector. Trigger frequency can be from 1MHz to about 200MHz.
Thanks
Leo
http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295 (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295)
Leo, is this a new PCB design, or just a mod to a few existing units? (i.e. will it be a feature going forward?)
Also, with the external input, is it possible to change back to the 10MHz TCXO, or is it a permanent change? Most of the time I'd want to use the on-board oscillator, but an external input would be useful sometimes too (for me, more so than a trigger output).
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It's a permanent mod on existing PCB. It might make it into the design in the future but I don't have anything imminent planned.
Leo
I have modified a few units to take external trigger input instead of on-board TCXO.
Leo, is this a new PCB design, or just a mod to a few existing units? (i.e. will it be a feature going forward?)
Also, with the external input, is it possible to change back to the 10MHz TCXO, or is it a permanent change? Most of the time I'd want to use the on-board oscillator, but an external input would be useful sometimes too (for me, more so than a trigger output).
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Figured I might as well join in the crowd and share my screenshot. 2.5Ghz optioned MSO6004X, best result 114ps rise (*way* more scope than I need, but handy for some stuff I'm doing).
This is one of the 2.92mm versions as that's all Leo had in stock at the time, so there's also an SMA to BNC on it as well (yes I know I shouldn't do that to a 2.92), IIRC it tested out below 30ps.
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Press Release (https://www.picotest.com/downloads/INJECTORS/Picotest%20Releases%20New%20PerfectPulse%20Signal%20Generator%20TDR_REV1_072618.pdf)Contact Information: Picotest.com Steve Sandler - Steve@picotest.com (877) 914-7426
June 6, 2018 Phoenix, AZ: Picotest.com, a leader in high resolution test and measurement equipment, has released a new, low cost, pocket-sized, fast edge signal generator and TDR in one convenient package. “Such a high speed, precise TDR/TDT has never before been available in this portable form, requiring only a USB power source, and at this price point,” according to Steve Sandler, Picotest CEO.
What can you say? "At this price point" is technically correct.
Leo - have you seen the Picotest product? They are selling a USB powered pulse gen for $3,500!!!
https://www.picotest.com/products_J2151A.html (https://www.picotest.com/products_J2151A.html)
Their game of 10,000% profitability will be abruptly finished at the moment when the Chinese start copying it from 5% profitability of the price components :)
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Why all the hate? geez. For one, picotest's is significantly faster than Leo's original (but on par with latest version). No over/undershoot and lots of features. Encapsulated as a dongle.
The cost of electronics is never the BOM cost. For the number of units they will probably sell, I doubt they'll break even on the R&D and the mold cost for the enclosure.
I'm just saying, they put thought and effort into it. They have salaries to pay. It's not fair to pick on them. It's totally different when it's a commercial product vs a one-man effort. You don't have to hate on the pico product to appreciate Leo's.
That said, I think I am going to pick up another Bodnar unit. :)
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Is there any hope to see Leo's edge on a UXR?
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Leo, your sales page (linked from post#1) says both "sold out" and "in stock". Which is it please.
(not being critical here, just want to point out this is an example of costs that go into a commercial offering of the sort that picotest has. they have "people" to pay that manage the storefront. they could not tolerate this kind of mistake, even though it is a small one. they have to keep a polished corporate image. etc.)
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Why all the hate? geez. For one, picotest's is significantly faster than Leo's original (but on par with latest version). No over/undershoot and lots of features. Encapsulated as a dongle.
The cost of electronics is never the BOM cost. For the number of units they will probably sell, I doubt they'll break even on the R&D and the mold cost for the enclosure.
I'm just saying, they put thought and effort into it. They have salaries to pay. It's not fair to pick on them. It's totally different when it's a commercial product vs a one-man effort.
That said, I think I am going to pick up another Bodnar unit. :)
With low volume specialist products the BOM cost quickly loses relevance.
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Leo, your sales page (linked from post#1) says both "sold out" and "in stock". Which is it please.
Sorry, SMA and 2.92mm versions are out of stock and waiting to be made next week.
The "sold out but in stock" bug is a known feature of the website - it is powered by Zen-cart so a bit transcendental sometimes.
Good criticism is very welcome!
Leo
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I know that our website looks a bit shabby but we are a small company of four and a half people with no time for polishing our image.
If I were to buy a commercial pulser [in the absence of mine] I'd probably go for http://www.hyperlabsinc.com/HL9201.aspx (http://www.hyperlabsinc.com/HL9201.aspx) from Agoston Agoston - the man who designed a lot of Tek sampling scope heads.
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Leo - have you seen the Picotest product? They are selling a USB powered pulse gen for $3,500!!!
https://www.picotest.com/products_J2151A.html (https://www.picotest.com/products_J2151A.html)
That comes with a directional coupler, though, doesn't it?
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Leo - have you seen the Picotest product? They are selling a USB powered pulse gen for $3,500!!!
https://www.picotest.com/products_J2151A.html (https://www.picotest.com/products_J2151A.html)
That comes with a directional coupler, though, doesn't it?
Indeed, it does. Curious how the kit breaks down in price.
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Its actually just a resistive power divider by the looks of it since those tend to be used for TDR while network analyzers use directional couplers.
Still that being said a 10GHz resistive power divider is still not very cheap. I built my own before that seamed to work well to 3GHz (Thats as far as the network analyzer could go), but i would imagine its a lot more difficult to diy a power splitter for 10 GHz.
I had a plan to try making one DIY and testing it for >10GHz but i never got around to it and my 22GHz spectrum analyzer needs some repair (Proabobly old caps in the PSU)
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Directional coupler edge over power splitter is its lower insertion loss but the downside is, typically, lower bandwidth. Or risetime degradation, depending on how you look at it. Most classic TDR heads I have seen use power splitters.
Do you want me to look into making one available?
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Hi Leo!
Why do you use that chunky usb port, and not micro-usb / usb-c ?
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Directional coupler edge over power splitter is its lower insertion loss but the downside is, typically, lower bandwidth. Or risetime degradation, depending on how you look at it. Most classic TDR heads I have seen use power splitters.
Do you want me to look into making one available?
I would be a customer.
Looking into fabricating my own for my 20Ghz sampling scope/TDR. I was thinking of machining the PCB for the 3.5mm connectors and hopefully finding some RF friendly 16.6 Ohm resistors. Then machine an RF sealed enclosure for it.
Then I just need to find someone to help me characterize the result. If they were available for a palatable cost - I would just buy it. >20Ghz is generally rather $$$$
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Why do you use that chunky usb port, and not micro-usb / usb-c ?
Have you ever tripped over the cable in the same micro-usb port twice? :)
Leo
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Hi Leo!
Why do you use that chunky usb port, and not micro-usb / usb-c ?
Those are blatantly hipster USB connectors!
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I like the big chunky USB connectors. These microUSB connectors are crap, they might be rated for more insertion cycles, but they break easier than any other USB connectors and are the most anoying kind of USB connector to plug in with your eyes closed. The previous miniUSB was pretty standard, more robust and easier to plug in while not really being all that much bigger.
I don't have any photos of my DIY power splitter, but what i basically did was solder 3 troughhole SMA connectors together into a star shape with the center pins pointing together. I soldered 0402 size resistors (I think you need 16.7 Ohm each for 50 Ohm at the port) from each SMA together into a common summing point in the middle. The small SMD resistors behave reasonably well a high frequency due to there small parasitics and flat straight construction. To finish it off i wrapped the whole thing in metal tape so that the resistors are completely shielded inside. Soldering those tiny resistors in mid air like that can be a bit annoying but you can throw one of these together in 10 minutes out of parts you likely have laying around.
Here is an example of a similar one that someone else built: http://www.simonsdialogs.com/2014/12/resistive-power-splitter-trying-out-a-low-cost-construction/ (http://www.simonsdialogs.com/2014/12/resistive-power-splitter-trying-out-a-low-cost-construction/)
It also worked perfectly good to 3 GHz, but again no measurements beyond to see where the limits really are.
Im guessing with careful controlled impedance PCB design and keeping connections short you could build one of these to perform nicely even past 10GHz. Resistors are dirt cheep but the PCB and the connectors could get expensive in a hurry for such high frequencies.
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This resistive splitter is way lower cost than I expected.
https://www.minicircuits.com/WebStore/dashboard.html?model=ZFRSC-183-S%2B (https://www.minicircuits.com/WebStore/dashboard.html?model=ZFRSC-183-S%2B)
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I like the big chunky USB connectors. These microUSB connectors are crap, they might be rated for more insertion cycles, but they break easier than any other USB connectors and are the most anoying kind of USB connector to plug in with your eyes closed. The previous miniUSB was pretty standard, more robust and easier to plug in while not really being all that much bigger.
I don't have any photos of my DIY power splitter, but what i basically did was solder 3 troughhole SMA connectors together into a star shape with the center pins pointing together. I soldered 0402 size resistors (I think you need 16.7 Ohm each for 50 Ohm at the port) from each SMA together into a common summing point in the middle. The small SMD resistors behave reasonably well a high frequency due to there small parasitics and flat straight construction. To finish it off i wrapped the whole thing in metal tape so that the resistors are completely shielded inside. Soldering those tiny resistors in mid air like that can be a bit annoying but you can throw one of these together in 10 minutes out of parts you likely have laying around.
Here is an example of a similar one that someone else built: http://www.simonsdialogs.com/2014/12/resistive-power-splitter-trying-out-a-low-cost-construction/ (http://www.simonsdialogs.com/2014/12/resistive-power-splitter-trying-out-a-low-cost-construction/)
It also worked perfectly good to 3 GHz, but again no measurements beyond to see where the limits really are.
Im guessing with careful controlled impedance PCB design and keeping connections short you could build one of these to perform nicely even past 10GHz. Resistors are dirt cheep but the PCB and the connectors could get expensive in a hurry for such high frequencies.
I was looking at 3.5mm connectors - which are indeed rather pricey. Vishay (and others) makes specialized RF resistors - but I have not found them in 16.66 Ohm. I thought about using 3x 50Ohm in parallel but that would be a mess to a >10Ghz signal.
The RF resistors are super expensive as well (relative to normal resistors)
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No, they are not expensive.
€2.12 qty 1, for the complete divider to 20 GHz, 0603 size all together.
< https://www.digikey.de/product-detail/de/susumu/PS1608GT2-R50-T1/408-2049-1-ND/7035422 (https://www.digikey.de/product-detail/de/susumu/PS1608GT2-R50-T1/408-2049-1-ND/7035422) >
regards, Gerhard.
(and I disagree on the micro USB.)
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Those are blatantly hipster USB connectors!
Usb C is supposedly more sturdy, but the proof is in the pudding.
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This resistive splitter is way lower cost than I expected.
https://www.minicircuits.com/WebStore/dashboard.html?model=ZFRSC-183-S%2B (https://www.minicircuits.com/WebStore/dashboard.html?model=ZFRSC-183-S%2B)
And I recently bought some at a ridiculous price, so there was no point for fuss. :)
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A few more data points. :)
Just got one of Leo's lovely little 40ps pulser's this morning. 50Ω terminations used.
Scopes:
1. Tektronix 2445
2. PicoScope 5244B with and without ETS engaged
NOTE: After I made this post I learned that 0.35 should have been the factor used for both my analog and digital scopes. See the following posts for the "why" on that.
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2. PicoScope 5244B with and without ETS engaged
Any specific reason to use 0.45/RT not 0.35/RT for calculation?
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Any specific reason to use 0.45/RT not 0.35/RT for calculation?
Ignorance probably! :)
My background is audio and I'm a bit of a newbie in this realm. From what I've read up to the point of my post yesterday is that it was appropriate to use 0.35 with analog scopes and 0.45 with digital. This of course is not very satisfying because the "why" isn't addressed. And then last night I found some articles by Tektronix and Keysight that not only addressed the "why" but made sense and of course the sources are pretty reliable. I particularly liked "the rule of 5's".
This kind of thing is approximation of course, but now it seems that 0.40 and 0.35 may be the better numbers to go with. The higher number is to be used with analyzers that employ maximally flat low pass filters in their design (generally digital domain > 1GHz) and the lower number is used < 1GHz where Gaussian low pass filters are generally employed. Based on this, I can see where the digital vs. analog scope thing came from, but the filter roll-off rate gets to the heart of the matter.
Keysight's article is excellent:
https://literature.cdn.keysight.com/litweb/pdf/5989-5733EN.pdf
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AFAIK, picoscope should have Gaussian response, in which case 0.35 would be correct..
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BTW this is stellar example of ETS usefulness. There is difference even at 1GSa/s, despite wfm looking entirely plausible and well reconstructed. And when you enable 2 channels still should have 20GSa/s on both, while with RTS you drop to Nyquist (practical) minimum and lose all detail.
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AFAIK, picoscope should have Gaussian response, in which case 0.35 would be correct..
I'm sure you're right. I just watched all the Pico Tech tutorials and one specifically used the 0.35 coefficient when discussing the 5000 series models such as I have. I also threw out a question to Pico Tech's support about the low pass filter employed and I'm a bit incredulous of the answer that it "...is not based upon a any intentionally designed filter."
Full context:
Hi,
The bandwidth states that the output remains within -3dB of the peak voltage (which is the standard specification for our PicoScope range). This is not based upon a any intentionally designed filter. The input stage of the PicoScope 5244D (the currently available model) in general has a rolling off effect of signal bandwidth (as do all electronic circuits at the extremes of their operation). So it starts a gentle roll-off quite early on, but remains within the spec right across the stated bandwidth range. It is very common for oscilloscope manufacturers to rely on the natural performance of their analogue circuitry to define the bandwidth of the scope.
Regards,
Pico Technical Support Team
As a card carrying member of Dave's "Young Player" crowd, I put together the following summary of rise time and bandwidth and would love corrections as needed, thanks!
Bandwidth and Rise Time Math
BW = (1/RT) * 0.35 for scopes < 1GHz due to Gaussian LP filters
BW = (1/RT) * 0.40 for scopes > 1GHz due to Maximally Flat LP filters
RT = (1/BW) * appropriate coefficient per LP filter type
Net Bandwidth:
BWn = 1/√((1/BWa)^2 + (1/BWb)^2)
Example: 70.7MHz = 100MHz scope with a 100MHz probe
Net Rise Time:
RTn = √(RTa^2 + RTb^2)
Example: 2.8ns = 2ns scope measuring a 2ns signal
Rule of 5's:
To minimize measurement error, it seems that this rule applies across the
board: scope BW 5x signal, scope RT 1/5th signal, sample rate 5x BW, etc.
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AFAIK, picoscope should have Gaussian response, in which case 0.35 would be correct..
I'm sure you're right. I just watched all the Pico Tech tutorials and one specifically used the 0.35 coefficient when discussing the 5000 series models such as I have. I also threw out a question to Pico Tech's support about the low pass filter employed and I'm a bit incredulous of the answer that it "...is not based upon a any intentionally designed filter."
This is probably right for most lower frequency scopes in the sense that the 0.35 arises from a simple R in with a C to ground. The 0.35 is actually ln(9)/2.pi if you do a simple calculation based on such a circuit (the 9 comes from a 10% to 90% rise). The input circuit is probably not primarily designed as a filter.
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I can't recall where exactly I got 0.45 coefficient from but quick search produces:
"It's 0.35 but in reality it's 0.45 or more..." (https://www.picotech.com/library/oscilloscopes/rise-time)
"0.45 is new 0.35..." (https://www.tek.com/support/faqs/how-bandwidth-related-rise-time-oscilloscopes)
etc...
I'd rather see the coefficient written as 0.4±0.05 or just 0.4 - in many natural sciences the default rule is that if some value is written as 0.35 or 0.40 with no stated error the last digit is assumed to be significant, i.e. implied estimated error is 0.01 or less.
To [an old] physicist BW ≈ 0.35 / tR really means more of a BW = (0.35±0.01) / tR
If you have not used slide rule or log tables in anger then it probably does not irk you.
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I can't recall where exactly I got 0.45 coefficient from but quick search produces:
"It's 0.35 but in reality it's 0.45 or more..." (https://www.picotech.com/library/oscilloscopes/rise-time)
"0.45 is new 0.35..." (https://www.tek.com/support/faqs/how-bandwidth-related-rise-time-oscilloscopes)
etc...
I'd rather see the coefficient written as 0.4±0.05 or just 0.4 - in many natural sciences the default rule is that if some value is written as 0.35 or 0.40 with no stated error the last digit is assumed to be significant, i.e. implied estimated error is 0.01 or less.
To [an old] physicist BW ≈ 0.35 / tR really means more of a BW = (0.35±0.01) / tR
If you have not used slide rule or log tables in anger then it probably does not irk you.
The 0.45 arises where the "filter" characteristics fall off more sharply which I think is the case for higher bandwidth scopes (1GHz and above). The nice thing about a simple RC model is that you can calculate things analytically and come to ln(9)/2.pi which appeals to me but of course the gross approximation is in assuming that the scope input can be modeled by a simple RC circuit.
Here is a Teledyne Lecroy blog on the subject:
http://blog.teledynelecroy.com/2018/02/transmission-lines-part-ii-more-on.html (http://blog.teledynelecroy.com/2018/02/transmission-lines-part-ii-more-on.html)
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Type of filter is sometimes clearly defined in specs for every scope :
Keysight MSOX3104T - 1GHz / 450 psec risetime - / 0.45 (Brickwall, min 2.5GS sample rate))
Lecroy Wavesurfer 10 - 1GHz / 350 psec risetime - / 0.35 (Gaussian, min 5GS sample rate)
But general rule is that you need circa 5x oversampling if you use Gaussian filter on input. If it is less than that, probably brickwall..
It is not connected so much with high bandwidth in scopes but more with oversampling ratio to avoid aliasing..
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Mine arrived. Thanks Leo!
Now to turn it into a ghetto TDR (which is what I bought it for).
(edit). Just applied the 20MHz filter and got 17.4ns ~20Mhz and the 100MHz filter and got 3.6ns ~97Mhz (using the 1/R * .35) approximation.
So the filters *do* work after all!
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One suggestion: could you please share the protocol specs to configure it? A Windows program is very inconvenient for someone not using Windows. It should be very easy to implement in Python, at least for simple command-line usage.
I'll try putting something together. You can only adjust output level and inversion, so it's not very exciting.
Leo
Any progress on this?
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Thanks for the reminder. We'll see if we can put it together this coming week.
Thanks
Leo
Update: we have plenty of BNC model in stock and a few SMA and 2.92mm available.
SMA and 2.92mm versions are still assembled manually so they are not always available off the shelf, please keep this in mind if you intend to snipe one.
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PicoScope 6404D 500MHz
Two pulsers attached, original <50ps BNC and ~30ps Oz version with negative going pulse / SMA / EXT trigger. Rise time wise no difference whatsoever. Magenta is BNC, Lime is SMA. EXT trigger is however very useful. First I cranked it to 25MHz for DeepMeasure to work at 200GSa/s (it needs full cycle), then set to 1MHz to enable single and only case of settings when fft(derivative(x)) works.
RT wise no surprises 0.35/603ns~=580MHz.
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=562816;image)
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Two pulsers attached, original <50ps BNC and ~30ps Oz version with negative going pulse / SMA / EXT trigger. Rise time wise no difference whatsoever. Magenta is BNC, Lime is SMA.
You need to use a bandwidth ten times more to try to find differences.
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You need to use a bandwidth ten times more to try to find differences.
Thanks for good TEA excuse :-+ Now I need a sampler just to see that difference :P But actually still bit surprise because SMA one is negative going so I had to apply DC offset and tune amplitude a bit, plus it has two adapters and sits on different channel. Still pixel-to-pixel overlap if sync timing & settings.
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Sorry, python control app is still in the works :-/O It's not a priority so it gets pushed around a bit. Maybe Christmas is the best time to finally nail it.
Some news: I have made a few custom modded versions with 100ps pulse keeping existing 10MHz pulse train.
I found that 80ps-1000ps pulse width is possible using existing PCBs.
This year the pulsers went to NASA, European Space Agency, Facebook, Tektronix, Rohde & Schwarz, many other T&M manufacturers and test labs.
We are in a good company, guys!
Leo
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Sorry, python control app is still in the works :-/O It's not a priority so it gets pushed around a bit. Maybe Christmas is the best time to finally nail it.
Some news: I have made a few custom modded versions with 100ps pulse keeping existing 10MHz pulse train.
I found that 80ps-1000ps pulse width is possible using existing PCBs.
This year the pulsers went to NASA, European Space Agency, Facebook, Tektronix, Rohde & Schwarz, many other T&M manufacturers and test labs.
We are in a good company, guys!
Leo
That is a very impressive track record there. :-+
Looks like deep down we all need to know how fast our scopes truly are.
By the way what is the intended use for that 100ps wide pulse?
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By the way what is the intended use for that 100ps wide pulse?
I do not know the details, this was a specific request from an R&D customer.
Leo
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This year the pulsers went to NASA, European Space Agency, Facebook, Tektronix, Rohde & Schwarz, many other T&M manufacturers and test labs.
Facebook?
Anyway, congratulations on your pulser's success. It's good to see that it has been "discovered" by such a wide range of customers. Far beyond just the TEA aficionados.
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Cheers, Tom. FB have hardware divisions.
Leo
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Yes, congratulations Leo. I was in this thread pretty early on and it seemed then like you felt this was just a side project. Instead it looks like it turned into a real product for you.
I don't have anything particularly fast in my shack, but it is sure nice to have a reference pulse I can rely on.
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Hi
This is my frist posting.
I has using S-2 sampling head with specified tr of 75ps. I have 2 faster sampling head (S-4 with tr of 25 ps ) but not BNC to SMA adapters.
I'll repeating measuring with S-4 head, if i get SMA-BNC Adapter.
Best regards
matt
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From your devices want to hide in trenches :D
I write about it with a sense of respect. They are as harsh and powerful as WWII tanks :)
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Matt...great vintage gear...I love old Tek stuff :-+
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Cheers, Tom. FB have hardware divisions.
Leo
In the news today:https://mashable.com/article/facebook-disbands-building-8/#gnOeGAa03qqm (https://mashable.com/article/facebook-disbands-building-8/#gnOeGAa03qqm)
Maybe the pulser they bought will show up on ebay.
The real value of Leo's tool for hobby dudes like myself is that it comes calibrated. I was unprepared for one thing though, the psychological after effects of seeing all the well endowed forum members posting their results and then comparing it to my measly LOL-RIG 300. :(
Now I have no enjoyment left in life, food doesn't taste as good as it used to and young women/girls point at me and snicker when I am out in public.
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Yes, leo's pulser is worth for money.
SMA-BNC is arrivied , i have trying with it and S-4 sampling head. Only a scrap, this adapter.
42ps , not bad, but reponse is not clean and it isn't repeatable. I'll trying again with better adapter.
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While I like good, working vintage equipment, old oscilloscopes have never had much draw for me...
But, you have shown me the light!
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Hewlett Packard an Tektronix has doing war with sampling oscilloscope in 1960s. HP sampling oscilloscope is a bit faster than Tektronix, but has not one automated oscilloscope in offers. Tektronix is pioneer of automated measuring in 1960s. Very little & special market, this S-3100 family is offered into 1980s, but not many sells (below 2000 produced units ). (of coruse, small & special market )
One old men is always telling with glowed eye about biggest (S-3150) from S-3100 family. It is running with PDP-8.
http://w140.com/tekwiki/images/a/aa/S-3100_Series_Brochure.pdf (http://w140.com/tekwiki/images/a/aa/S-3100_Series_Brochure.pdf)
This oscilloscope and digital unit is heart-piece of this system.
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Thanks for sharing that link. That is really cool. I bet it cost a fortune.
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no problems. TekWiki (w140.com) is interressing site. Fortune, yes, old men talks about million franc (swiss, 1980s) for this big automated machine.
I think,i am leading monologue :-)
Telegärtner* Adapter ist arrivied, it is much better than china-stuff.
faster risetime and smoother reponse. I have using torque wrench from Radiall for SMA for fixing adapter at S-4 sampling head.
* a german company for connector, also good stuff.
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Any EEVBlog member discount for those who don't have FB/NASA-level deep pockets? ;)
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The price already has any possible discounts in. NASA is just paying EEVBlog price, not the other way round.
Leo
Any EEVBlog member discount for those who don't have FB/NASA-level deep pockets? ;)
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The price already has any possible discounts in. NASA is just paying EEVBlog price, not the other way round.
Leo
Fair enough - I think the price is totally worth the effort that obviously went into this. However in the words of my long gone father, "never hurts to ask". :)
Cheers!
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Siglent SDS2352X-E + 50ps BNC pulser into native 50Ω
0.35 / 0.9ns ~= 389MHz
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=612403;image)
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Shahriar of The Signal Path did a really nice review of Leo Bodnar's pulse generator in November, that I just came across.
https://www.youtube.com/watch?v=T-G4OhWSyIo (https://www.youtube.com/watch?v=T-G4OhWSyIo)
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This pulse generator also got into a video on HackADay:
https://youtu.be/STCGzanAyR0?t=630
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Thanks Leo for the super-fast shipping!
Here are screenshots of the BNC PULSER into a Keysight MSOS804A scope, showing real-time and equivalent-time sampling modes. Fastest indicated transition is 53.2ps. This scope has a brickwall filter around 8.4 GHz.
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When you see the wiggles BEFORE the edge you know it's DSP voodoo in action...
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When you see the wiggles BEFORE the edge you know it's DSP voodoo in action...
You mean data before trigger? :) Some scope have continuous capture and digital trigger, they may show data before trigger... But this should be mentioned in spec :). I know R&S have this.
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That you can see the history before the trigger, that is old.
Even historic analog scopes had a delay line good for some 20 nsec.
But when the ringing starts before the edge that excites it, then there
must be something that can look into the future.
Or there is a prettyfier algorithm at work that massages the data
until fit for display.
I'd prefer causality.
Cheers, Gerhard
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When you see the wiggles BEFORE the edge you know it's DSP voodoo in action...
It isn't voodoo. It is the Gibbs phenomenon.
I was taught about it in school (UK school, i.e. before university). Draw a graph of sin(x)+1/3sin(3x)+1/5sin(5x) and you will see it too.
The Gibbs phenomenon can be seen in both analogue and digital signal processing.
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It's not that ideal brick-wall filter looks into the future. It just takes infinitely long time to accumulate [and process] data.
Leo
That you can see the history before the trigger, that is old.
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Yep even analog filters can give the "pre wiggle"
Its not seeing into the future, instead the filter is delaying the waveform so much. When the wiggles start the filter has already got the edge on its input, but it takes a while for the edge to make it trough the filter magic and appear on the output. Filters have to cause these delays in order to observe what the waveform is doing around the point.
But yeah most brick wall filters are implemented digitally because its easier to do these days.
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Of course, it does on the screen. At t = -200 ps, we cannot yet be sure that the rising edge
will come at all, there still could be a dropping clock enable, but the trace is already
shivering in anticipation of the things to happen. That is simply wrong. We do not want
a brick wall filter, it is only there so that marketing can advertize more -3dB bandwidth than is really
usable. When I see that step response: Is that pre-edge ringing the ground bounce of my driver
chip, or capacitive feedtrough trough the driver, or is it just an artefact?
If it is an artefact, is the ringing after the edge also an artefact, or do I have a little resonator
somewhere? It looks so identical to the time when we could not know if the pulse would fire at all.
If you read the book of Hollister on wideband amplifier design or that of Staric, you can see
what amount of work they used to put at Tektronix into their Y amplifiers, just to get a clean
step response. That has been replaced by marketing in the mean time.
Is there any pre-ringing in the screen dumps of that old 68030-based sampling scope?
Which scope should I trust when I tune the bias tee?
< https://www.flickr.com/photos/137684711@N07/46284720054/in/album-72157706443876665/ (https://www.flickr.com/photos/137684711@N07/46284720054/in/album-72157706443876665/) >
(54751A 20 GHz plug in & 54754A 18 GHz differential TDR, and the pics left/right).
I have made these pictures this week for a discussion of bias tees on usenet sci.electronics.design.
regards,
Gerhard
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So, there is actually no pre-ringing, it's just an artifact of interpolation?
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So, there is actually no pre-ringing, it's just an artifact of interpolation?
That says it all:
https://en.wikipedia.org/wiki/Gibbs_phenomenon
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So, there is actually no pre-ringing, it's just an artifact of interpolation?
Interpolation is irrelevant.
It is the Gibbs phenomenon. That has been known about for longer than electronics have been around!
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This happens whenever a fast edge is passed through an ideal sinc reconstruction filter in a system with enough time-domain resolution to portray the artifact accurately. The ripples you see are basically caused by the ripples in the graph of sin(x)/x.
There are plenty of other low-pass kernels that won't exhibit as much Gibbs ringing -- such as the Gaussian response being discussed farther up the thread -- and ideally the scope would allow you to select from one or two different ones. But the sin(x)/x kernel has the advantage of being the 'correct' one that will represent the band-limited edge optimally.
If you follow the rabbit hole down far enough, you will meet a fellow named Heisenberg who isn't sure where the exit is.
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If you follow the rabbit hole down far enough, you will meet a fellow named Heisenberg who isn't sure where the exit is.
He's certainly an evil fellow that kills kittens...
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Physical analog systems are minimum phase. This has nothing to do with Willard Gibbs and everything to do with Hendrik Bode.
As physical systems are minimum phase as shown by Bode and many others, using a zero phase sinc(x)/x is pretty lame in a DSO. as it does not conform to physical reality. and a minimum phase sin(x)/x is no more complex. It's just a different set of coefficients.
You can make the sin(x)/x interpolator pure causal by applying a Hilbert transform. While this would be *highly* unusual in seismology (we tend to like symmetric wavelets and routinely zero phase data using impulse responses of the recording system) it does make good sense in electronics.
Gibbs has *nothing* to do with it. Gibbs did not describe "pre-ringing". What he showed was that the spike at the peak of a step was a mathematical consequence of the Fourier series. Or to put it differently, if you don't want overshoot you need to modify your step response spectrum.
The more I read comments about DSP from forum members for whom I have great respect, the less regard I have for the DSP training of EEs. I'd always assumed they knew more about DSP than geophysicists, But then, most EEs do a little DSP, whereas seismic processors do nothing else. And reflection seismic research scientists spend all their time inventing new DSP algorithms. In general the DSP for reflection seismology is so highly developed that no individual could master all of it.
FWIW the sin(x)/x interpolator is also called a "Whittaker" interpolator.
Those are the facts and nothing but the facts. How anyone can involve Heisenberg in this is completely beyond me. All the mathematics were proved long before I was born.
As a general reference, "Random Data" by Bendat & Piersol 4th ed is the best summary of the subject which was developed primarily by Wiener, Shannon, Nyquist and Whittaker in the 30's and 40's.
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Those are the facts and nothing but the facts. How anyone can involve Heisenberg in this is completely beyond me. All the mathematics were proved long before I was born.
There's a very intimate connection between the uncertainty principle and the time/frequency duality encountered in DSP work. If you haven't encountered that before, it may be a good idea to look into it (https://www.quora.com/How-does-the-uncertainty-principle-relate-to-Fourier-transforms). It's pretty neat stuff.
The rest, I'll leave up to others to argue with you about, being (apparently) short on the requisite education and experience. :)
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I don't think that the change in frequency resolution due to windowing has anything to do with Heisenberg. It's a natural consequence of truncating the time window. Yes, there is a duality. You can have precise frequency and imprecise time or the reverse. But I'd love to see how Heisenberg's observation about location and velocity derives from a simple convolution problem. Is there a convolution hiding in Heisenberg?
The time-frequency resolution issue is why I viewed wavelets with disdain for many years. However, after reading Mallat's 3rd ed it became clear that the only problem with wavelets was people misrepresenting them. Mallat addresses my objection to what I often heard at professional society presentations and is in complete agreement with my position on the subject.
Or as I once put it, "if a statement is true in English, it cannot be false just because it is made in another language."
However, that's not my reason for posting.
I've had a pair of Leos pulsers, the square wave and the impulse version, my 33622A and one of Leo's dual channel GPSDOs set to 10 MHz on a 200 MHz DSO. I can adjust the 33622a in 0.01 Hz steps, 1 ppb at 10 MHz. It drifts a bit over time but is easily readjusted to be withing 0.5 ppb or less of the GPSDO. The behavior of the pulsers is quite interesting. Initially I thought the issue was the size of the TC step, but it turns out that the culprit is air movement. Wrapping a towel around the pulsers greatly reduced the frequency jitter.
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I suppose velocity and position are related in a similar way as frequency and phase are related. But Heisenbergs uncertainty principle also involves Planks length, while we don't really have something like it with frequency. So id say the idea is similar but not the same thing.
Oh and you can see drift in just about anything if you measure it with enough resolution. But measuring frequency and time is the easiest quantity to measure to a really high number of digits. For example i turned a relay into a PIR sensor by simply hooking it up to a high resolution DMM. Putting my hand 50cm above the relay would cause the resistance to start climbing up, removing my hand would make it slowly drop back down. Shining a light from a distance on the relay also had a similar effect (again warming the coil a tiny tiny amount by radiation).
So in theory you could use the pulse generator to detect if the light in your room is on or off provided you measured it carefully enough and had no other outside disturbances.
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The Fourier transform is an integration from negative to positive infinity. As soon as you truncate the integration you are convolving the signal with a sin(f)/f. That's the source of the time-frequency resolution trade off. That's 200 year old mathematics.
I had largely ignored wavelets because of assertions that wavelets circumvented that. After my first reading of "A Mathematical Introduction to Compressive Sensing" by Foucart and Rauhut, I realized I really needed to read all of Mallat's 3rd ed. Mallat discusses the implications of Fourier analysis in relation to wavelet analysis in considerable detail. And the mathematics of wavelets is essential to understanding F&R.
I'm not familiar with Heisenberg's analysis as I never took quantum physics. But I'd be surprised if a phenomenum described 100 years earlier would get named after someone who reinvented it. Both form the horns of a dilemma, but very different mathematically.
With a cloth towel wrapped around it, the jitter in the pulser output drops into ppb territory. There are occasional frequency shifts. But for periods of up to at least 20-30 seconds the jitter is almost as good as the 33622A which is specified at under 1 pS and observation shows it is much less than that. How much less I won't know until I get my LeCroy synced to a GPSDO. I'm currently looking at the stability of the DSO timebase.
As a consequence of yesterday's experiments I'm going to enclose my impulse unit with glass wool and heatshrink to see how much it improves the frequency stability. At this moment, the towel wrapped square wave unit which has heatshrink, but no glass wool, is sitting stable within a few ppb of 10 MHz with frequency shifts well below 1 ppb over longer than I want to look at it. If I get the expected result from adding the glass wool I'll recover the square wave unit.
Modern measurement capabilities are astonishing. JBeale's inclinometer thread is a great example. The results he and others got boggles the mind. A 2 axis version is on my To Do list. Once it is working I am going to see how accurately I can measure the level of the lake a mile from my house using the elastic deformation of the crust.
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There's a very intimate connection between the uncertainty principle and the time/frequency duality encountered in DSP work. If you haven't encountered that before, it may be a good idea to look into it (https://www.quora.com/How-does-the-uncertainty-principle-relate-to-Fourier-transforms). It's pretty neat stuff.
The two ideas are totally unrelated.
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The two ideas are totally unrelated.
No, they are not. (http://www.ams.org/publicoutreach/feature-column/fcarc-uncertainty)
I'd be curious to understand why so many people seem to take the idea as some kind of personal affront. It seemed like an uncontroversial thing to post at the time, and it seems like a pointless hill to die on now.
I don't see why the relationship between Fourier theory and the uncertainty principle should evoke any reaction stronger than the one I had when I first encountered it, which is, "Hmm, that's kind of neat." What am I missing?
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The two ideas are totally unrelated.
No, they are not. (http://www.ams.org/publicoutreach/feature-column/fcarc-uncertainty)
Not sure how this sentence should be interpreted:
1) "No, they are not related."
or
2) "No, they are not totally unrelated."
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Not sure how this sentence should be interpreted.
Werner says: "Trying to interpret a sentence might affect its meaning."
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2) "No, they are not totally unrelated."
That would be #2. They are not unrelated, at least according to that particular essay from the American Mathematical Society, the reference I posted earlier, and any number of other citations that are similarly easy to dig up.
Reginald is entirely correct in one respect, which is that I'm distinctly unqualified to pick up a piece of chalk and defend the point. I'll concede and be satisfied with muttering Eppur si muove under my breath if it will keep peace in the family. :)
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2) "No, they are not totally unrelated."
That would be #2. They are not unrelated, at least according to that particular essay from the American Mathematical Society, the reference I posted earlier, and any number of other citations that are similarly easy to dig up.
Your link is not to an essay by the American Mathematical Society.
Heisenberg's Uncertainty Principle is about the fundamental uncertainty in observables that arises when their associated operators are non-commuting. It is strictly a quantum phenomenon. The equations may look similar to those describing a pair of classical conjugate variables (e.g time & frequency), but they are unrelated concepts.
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2) "No, they are not totally unrelated."
That would be #2. They are not unrelated, at least according to that particular essay from the American Mathematical Society, the reference I posted earlier, and any number of other citations that are similarly easy to dig up.
Your link is not to an essay by the American Mathematical Society.
No, it's to an essay from the American Mathematical Society, more specifically published under their masthead.
I'm done here. It's been weird.
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If I'm standing outdoors and getting wet, being rained on is not the same as getting sprayed with a hose. Even if the water is falling on me vertically. In the latter case, walking a few feet will change things. That's the best I can come up with as an analogy. I've seen a lot of stupid errors because people were sloppy about such distinctions. In particular in geodesy where the errors lead to spending many millions of dollars drilling wells in the wrong location.
My sensitivity about such things is not personal. It's the sort of thing I was paid to do. When I terminated my contract with a supermajor in 2007 at 55 and left Houston to look after my parents in Arkansas I had just finished constructing a 600 x 300 x 6 mile model of rock properties and especially pore pressure in the GoM from a half TB of data.. That work was a regional study. But I was doing a brisk trade on the side doing pore pressure predictions for individual wells for the deepwater business unit where well costs were typically $50-150 million. One well I worked on was the third $50 million well being drilled on the prospect. The other two wells had to be abandoned because of excessive pressure.
Macondo was an organizational failure by BP. They'd reached TD, but drilling operations blew it while plugging the well. A rig like the Deepwater Horizon rents for $500,000/day. They were in a hurry to move move to the next well. I've not bothered to research it even though I own BP stock as a consequence of working for Amoco in the early '80's. But from what I've read it appears that the total bill for that disaster was $40 billion. Do that kind of work as long as I did and you too will be *very* particular about details other people ignore.
Back to the thread topic.
I've got my 33622A linked to the GPSDO and the DSO triggering off the 33622A. My impulse unit is now insulated with some glass wool and heatshrink. The square wave unit is just heatshrink with some electricians tape to close off the ends. Both units are running within 1.5 ppm at a room temperature of 80 F. The actual error varies by about 1 ppm. I can adjust the 33622A in steps of 10e-6 Hz. I'd thought it would adjust in steps of 10e-2, so I'm a bit agog at 10e-6 steps.
At the moment the impulse unit is very stable, but the square wave is jumping around, sometimes fast, sometimes slow and sometimes spot on the 33622A (at 0.9 ppm slow). Or it was when I started typing.
Now both are jumping around, but I have no way to tell if it's the pulsers or the DSO timebase. So next up is to sync the LeCroy DDA-125 to the other channel of Leo's GPSDO.
In any case very interesting and fun.
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2) "No, they are not totally unrelated."
That would be #2. They are not unrelated, at least according to that particular essay from the American Mathematical Society, the reference I posted earlier, and any number of other citations that are similarly easy to dig up.
Your link is not to an essay by the American Mathematical Society.
No, it's to an essay from the American Mathematical Society, more specifically published under their masthead.
Am I clicking on the wrong link? Post #479 ("look into it") -- that link takes me to Quora.com.
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Am I clicking on the wrong link? Post #479 ("look into it") -- that link takes me to Quora.com.
There were two links. The link in my first reply to rhb went to a page on Quora where someone asked, "How does the uncertainty principle relate to Fourier transforms?" The top answer is from a physics prof at Berkeley. It was just the first thing I found when I Googled for a citation, at a point when I didn't expect to have to defend it like a PhD thesis. :-//
The second link I posted was the one that went to the AMS website, which was the second thing I found when I Googled for a better citation than the evidently-inadequate one on Quora.
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Am I clicking on the wrong link? Post #479 ("look into it") -- that link takes me to Quora.com.
There were two links. The link in my first reply to rhb went to a page on Quora where someone asked, "How does the uncertainty principle relate to Fourier transforms?" The top answer is from a physics prof at Berkeley. It was just the first thing I found when I Googled for a citation, at a point when I didn't expect to have to defend it like a PhD thesis. :-//
The second link I posted was the one that went to the AMS website, which was the second thing I found when I Googled for a better citation than the evidently-inadequate one on Quora.
Okay, thanks. I see the second link.
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I also got the Quora link.
Heisenberg's principle relates the location of a particle to its velocity which is the time derivative of location.
The time derivative of a sine is a cosine, but the cosine is not the Fourier transform of a sine. Nor is the time derivative of a Gaussian, a Gaussian.
So there's a rather large step from the time-frequency ambiguity of the Fourier transform to invoking that ambiguity in the case of the location-velocity ambiguity of quantum mechanics.
I am fine with saying that the two are analogous. What I'm not OK with is saying they are equivalent. Unless you can present a mathematical proof. And for the reason cited above I find that a serious stretch. I'd be genuinely interested if that can be shown. I'll look at the AMS link in the morning.
My 3 year foray into sparse L1 pursuits, aka compressive sensing, took me into Grunbaum's monograph on regular polytopes in N dimensional space. Which is a *very* long way from literature and philosophy or any applied math I've dealt with previously. So I'm no longer the least bit bothered by texts written for mathematicians.
Show me.
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Heisenberg's principle relates the location of a particle to its velocity which is the time derivative of location.
No. Position and momentum are conjugate variables, with the momentum operator involving a derivative with respect to position, not time. (Energy and time are conjugate variables, with the energy operator involving a derivative with respect to time.)
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There are few problems with quantum mechanics: nobody understands it (https://youtu.be/w3ZRLllWgHI?t=23) while popular media dissolved it into memes and jokes which is great but makes everyone (and me too) think they do.
This discussion is fascinating because each side has a valid point.
I am curious whether apparent similarity would be more difficult (or impossible) to defend if the original author turned to matrix representation of quantum mechanics (which is fundamentally identical to wave one.) Heisenberg himself used matrix representation and totally hated and derided Schroedinger's wave form. Popular media somehow ignores matrix representation (and bra-ket notation at that) - possibly because it's not hipster enough?
By the way, Heisenberg discovered and formulated the uncertainty principle based on matrix representation.
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I'm attaching a few pages from "introduction to Quantum Mechanics" b Richard L. Liboff. I make no claim to understanding quantum mechanics beyond being aware of some of salient characteristics and why it was developed. Most of what follows is from a 10-15 minute skim of the opening chapters of Liboff.
Matrix notation is just a convenient shorthand, nothing more. In quantum mechanics one deals with a scalar and a vector in 3 space.
Liboff refers to position and momentum as "complementary variables" rather than tomato's "conjugate variables". There are a great many figures which superficially resemble Fourier transform pairs. They are not unless they deal with the wave nature of particles or instances of the Bohr correspondence principle which states that quantum mechanics must reduce to classical Newtonian physics in the limit as the quantum number approaches infinity.
There are as many meanings to a sentence as there are readers thereof. Each of us brings our own set of contextual references which we use to interpret the words. The "I'll look it up on the internet if I need to know" meme implies that those who endorse that have extremely limited communication skills, even when they are only reading. It gets far worse when they write.
Back to the original thread topic.
Leo, will the pulsers stand a short across the output? It seems to me that as they are capacitively coupled they will, but I'd rather ask than ruin one.
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Leo, will the pulsers stand a short across the output? It seems to me that as they are capacitively coupled they will, but I'd rather ask than ruin one.
Yes, they are fine with shorted output.
Leo
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I've ordered a BNC SOL cal kit from SDR-Kits. The first iteration of the TDR VNA software will use the impulse unit as it doesn't need as long a delay line, but I plan to make it work with the square wave unit as well. I you can only afford one, I think the square wave unit is more generally useful.
That's certainly true if you work on analog scopes, but may not be as important with current DSO designs as they really don't have much that can be adjusted. Two trimmer caps in the Instek GDS-2000E line. I've not been inside the Owon XDS2102A yet, but in 12 bit mode it should provide ~ 100 dB of dynamic range from a single 20 Mpt trace. That's on par with an 8753 and a pulser and cal kit totals 6% the price I paid for my 8753B w/ 85047A S parameter set. Obviously not the range of the 8753B, but if you're new to radio, HF is quite hard enough.
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I urge that prospective buyers exercise great caution when considering the purchase of one of these pulsers lest you too suffer from uncontrollable TEA.
I just got a Tek 11801 with a pair of SD-22 heads up and running. And it's all because of the CSA803 plots Leo provides with the units. Until I saw those plots, I'd never even considered buying a sampling scope. But after seeing them I *had* to have one. And I'm now searching for an SD-24 and an S30 or SD-32 to fill the other two slots.
You have been warned. ;-)
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I urge that prospective buyers exercise great caution when considering the purchase of one of these pulsers lest you too suffer from uncontrollable TEA.
I just got a Tek 11801 with a pair of SD-22 heads up and running. And it's all because of the CSA803 plots Leo provides with the units. Until I saw those plots, I'd never even considered buying a sampling scope. But after seeing them I *had* to have one. And I'm now searching for an SD-24 and an S30 or SD-32 to fill the other two slots.
You have been warned. ;-)
Perhaps it should just be called "CAN OF WORMS" or 'PANDORAS BOX"??
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I don't yet have a sampling head fast enough for Leo's products, but I'm pretty sure I'll get one. Of course, once I have that I'll have to try beating Leo. That's *highly* unlikely, but trying will certainly be educational.
The value of the education I've gotten from my square wave and impulse generators greatly exceeds the cost.
If you really want to understand electronics those two devices are the best investment you can make in terms of cost - benefit ratio if you understand the Fourier transform well.
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I was looking to get one of those scopes but couldn't find any for a good price. What finally sacred me off them is reading that they can often break and have hard to trace faults that sometimes require replacement of unobtanium parts so a donor unit is needed for spare parts. So yeah that made me scared to buy the cheap "sold as is" listings that i usually go for.
I still have a sampling module for it (I think a SD22) that i got for cheep. But i eventually came across a cheep HP sampling scope and a not too outrageously priced dual channel 20GHz sampling plugin module for it. Works well and is a bit more modern than the Tek, Im still hunting for a 40 GHz plugin module for it, but the going price for those modules is like over 2 or 3 grand on ebay.
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Half of CSA803/11800 heads that I have bought had some sort of faults - including ones sold as "working".
Some have lost their EEPROM integrity, which prevents CSA803 from accepting them and the rest had soldering problem.
One had hardline to SUB-D coax internal break. One had blown termination resistors. Others just had solder joints that fall apart. When you try re-soldering the pads, gold is sucked up and leaves awful black coloured unsolderable pads that are repelling solder.
Tek must have gone through rough patch with these heads quality. Mainframes are not that bad but are full of alien ICs.
Leo
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I was *very* lucky. The 11801 cost $100 + $85 shipping. It had been in storage in Arizona, so minimal risk of corrosion and the seller furnished a photo of the extended diagnostic screen showing an E5622 (NVRAM) error. I got two SD-22 heads for $150 delivered and an extension cable for $100 from other sources.
When the 11801 arrived it was DOA and failed the Kernel diagnostics. I opened it up and after reseating all the boards in the main card cage and all the connectors I could reach a couple of times it finally booted.
However, at that point I was dead in the water. Moving the jumpers on the I/O board did not let me get out of the diagnostics. Then Tom Miller on the TekScopes list suggested I remove the DS1213 "smart sockets" and plug the SRAM directly into the board. That did the trick, it skipped the self test and worked. When I shifted the jumpers back to the default position, it halted in the Extended Diagnostics with a T1331 error, but now I could exit by pressing "Exit" twice. With the E5622 error I could not exit the diagnostics.
When my replacement NVRAM arrived I installed them and after 3 reboots it works like a charm. At least so far as I can tell. I still need to read the user manual.
An 11801 that had been stored in a humid climate would require a complete disassembly to address corrosion of the sockets. and cable connectors. That would be a full day's work. With no component level data, board swapping is about the only viable repair. If you can get multiple units for what I paid or boards from a reliable source (e.g. the TekScopes list) they can be maintained.
But this is an issue with all newer instruments.
Leo, were you using 3% silver solder when you ran into the gold soldering problems? Also what are sensible price ranges for SD-24, SD-30 & SD-32 heads? Most of the asking prices on eBay are ridiculous. And then there are sellers who don't allow returns for DOA and are insulted if you offer less than what they are asking.
Fortunately, I don't need any of this, I just had to have one after getting the pulser plots from you. So I can wait to get additional heads at sensible prices.
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Now that was a really good bargin.
I had trouble finding then for under 400 bucks, perhaps i just had bad timing. For a 100 bucks i would have taken a risk of buying a potentially dead one and risking that might need to buy another for spare parts.
Then the HP sampling scope showed up for under 100 bucks and went for that, it worked perfectly with zero repairs needed. Tho it appears that a trimm cap for the timebase calibration is kinda wonky, its really touchy and random acting when tweaked, but so far it seams to hold up. Replacing a trimm cap is a easy fix anyway, but if it aint broke don't fix it. Tho come to think of it i don't think i even opened the lid on that scope to see whats inside, i usually like to take a look inside my test gear.
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The ringing you see on the step is caused by reflections at the interfaces of the SMA and 3.5 mm connectors. I've got two cables like that which are about 0.4 mm difference in length. I can set cursors on the peaks and read off the difference in the length of the cycle. However, this is really asking a lot of the SD-22 head as it's near the BW limit of the head.
Really quite amazing. The sampling is controlled by a 48 bit programmable delay with 20 fs resolution!
These are very much niche instruments. The asking prices on eBay are generally quite absurd. But not always. There's a CSA803 with an SD-46 head for $339. The SD-46 is a 20 GHz optical to electrical converter so you still need an SD-24 or SD-26 to time your fiber optic line.
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These are very much niche instruments. The asking prices on eBay are generally quite absurd.
It's because they have the worst user interface ever designed by man. It's worse than awful. I suspect a lot of them are in "like new" condition because engineers did not find half of the functions they needed.
True story: I could not find the way of changing the timebase for more than 40 minutes and had to resort to reading the operation manual. It turned out that function buttons on the front panel have state - you need to press them several times to get to the menu you need. From there it was just a few touchscreen taps (it actually reacts to finger withdrawal), knobs twists, menu presses and numberpad entries away.
Leo
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It actually makes the cheap Chinese DSO UIs look good. I didn't think that was possible.
BTW I've got the calibrator hooked to an SD-22 channel and cursors set at the peaks of the ringing from the mismatch between the 3.5 and SMA connectors. I've noticed that the waveform moves realtive to the cursors over a period of several minutes. Any ideas? I'm wondering if replacing the OXO with one of your GPSDOs would improve the time stability.
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Both SMA and 2.92mm versions are back in stock. http://www.leobodnar.com/shop/index.php?main_page=index&cPath=124 (http://www.leobodnar.com/shop/index.php?main_page=index&cPath=124)
Thank you for waiting so patiently!
Leo
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I've noticed that the waveform moves realtive to the cursors over a period of several minutes. Any ideas? I'm wondering if replacing the OXO with one of your GPSDOs would improve the time stability.
Somewhere back in this thread I posted some measurements and plots of the pulser output timing...
https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/msg1404693/#msg1404693 (https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/msg1404693/#msg1404693)
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This is not the pulser, I know about that. You can greatly improve the stability of those by insulating them. All I've tried so far is glass wool inside heat shrink. But I need to redo it with larger heat shrink and more glass wool.
This is the calibrator output of the 11801 which has an OXCO, at least I think it is. I'll open it up and check tomorrow. I'm currently testing CH 5 & 7 and seeing timing issues.
I'm going to be pulling it apart tomorrow and reseating cables, etc. These bays came with plastic covers, so they've probably not been used since it left the factory 30 years ago. I just bought four SD-26s so I need to get these bays working properly. Time to put some Dexoit on the connections.
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Hello
With a just received leobodnar pulser
Keysight DSOX-2022A (200MHz) 1.42ns with the Leo's BNC Inline Terminator 50Ohm, 1.7ns without.
Hameg HM407(40MHz !) : 7ns with, 8.8ns without .
Laurent
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I've got my pulsar two weeks ago.
I must have to say, it is worth every penny for it.
Dear Leo,
May I ask, do you have hungarian ancestry?
Kind regards,
Gyuri
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I've got my pulsar two weeks ago. I must have to say, it is worth every penny for it.
...
May I ask, do you have hungarian ancestry?
Thanks, TGyuri. Not that I am aware of! :)
Leo
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I got my pulser !!
Here are the first results. Even a little bit to try TDR.
Scope Tektronix MSO4104B.
Interesting how can I change the frequency of his work? How to reduce it? Or make it external? With TDR it turns out to test only fairly short cables :(
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Lecroy sda 820Zi:
3,5 GHz (BNC) input
20 GHz (sma) input (pulser+BNC-SMA connector)
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MegaVolt, sorry, but what was it now?
What kind of fabulous sma adapter did you use (homemade)?
Why did you use the cursor measurements in manual mode?
Equivalent mode is also preferred when you have a repeating signal.
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MegaVolt, sorry, but what was it now?
What kind of fabulous sma adapter did you use?
https://aliexpress.com/item/32831271535.html
And uto prevented you from applying the automatic measurement mode Rise time (10-90), instead of moving the cursors with your hands anywhere?
The screenshots have both methods of measurement. Automatic and manual.
And between them there are some differences. I think this is due to the fact that the signal is not a perfect rectangle. And for this, the automation does not quite correctly set the thresholds of 10% and 90% and get a slightly better time.
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MegaVolt, sorry, but what was it now?
What kind of fabulous sma adapter did you use?
https://aliexpress.com/item/32831271535.html
:palm:
Something went wrong in your lab. From an oscilloscope with a bandwidth of 20 GHz, one should have expected something better.
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Yeah a 20GHz scope should be getting somewhere around 50ps rise times out of it. The odd uneven rise time could hint at some impedance mismatch or connector issue. What sort of connectors does that scope have anyway?
And yeah id suggest using equivalent time sampling with some averaging on top to get a better look at the waveform.
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Your screen captures show about 1.2V signal amplitude.
Try reducing it to 700-900mV. Higher amplitude increases edge rise time on this particular pulser.
Leo
The screenshots have both methods of measurement. Automatic and manual.
And between them there are some differences. I think this is due to the fact that the signal is not a perfect rectangle. And for this, the automation does not quite correctly set the thresholds of 10% and 90% and get a slightly better time.
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For a 3.5 GHz scope with BNC/SMA converter about 150 something psec sounds fine to me ..
It is 20GHz bandwidth scope but on ProLink inputs. He used ProBus input, that one has 3.5 GHz bandwidth...
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For a 3.5 GHz scope with BNC/SMA converter about 150 something psec sounds fine to me ..
It is 20GHz bandwidth scope but on ProLink inputs. He used ProBus input, that one has 3.5 GHz bandwidth...
No, as far as I understood his message, in the last 2 screenshots he used the HF-input ProLink with the appropriate adapter.
If it is not, let him correct.
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For a 3.5 GHz scope with BNC/SMA converter about 150 something psec sounds fine to me ..
It is 20GHz bandwidth scope but on ProLink inputs. He used ProBus input, that one has 3.5 GHz bandwidth...
No, as far as I understood his message, in the last 2 screenshots he used the HF-input ProLink with the appropriate adapter.
If it is not, let him correct.
Sorry I wasn't paying attention.. I looked at first two ones .. |O
Thanks for pointing it out.
On two second ones he has quite a spread between minimum and maximum values, probably something wrong with connection.
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Your screen captures show about 1.2V signal amplitude.
Try reducing it to 700-900mV. Higher amplitude increases edge rise time on this particular pulser.
Leo
So much better.
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So much better.
You incorrectly set the cursors. You must count (10/90%) from the level of the flat plateau on the signal. For this you need to increase the time of the review. Usually, LeCroy automatic measurements do this correctly.
Also, you need to turn on the equivalent sampling mode (if you are not going to demonstrate the Nyquist Theorem here?).
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You incorrectly set the cursors. You must count (10/90%) from the level of the flat plateau on the signal. For this you need to increase the time of the review.
I set the thresholds exactly as you described. And then stretched the signal.
Usually, LeCroy automatic measurements do this correctly.
OK. No problems. Look at the bottom left for the numbers that Lecroy counted automatically.
Also, you need to turn on the equivalent sampling mode (if you are not going to demonstrate the Nyquist Theorem here?).
I do not understand. 80 gigasamples per second is not enough? This is a two-fold reserve from the Nyquist frequency.
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FWIW My LeCroy DDA-125/LC684DLX samples at 2 GSa/s with a 1.5 GHz anti-alias filter.
You can get away with being slightly undersampled as long as you do not go into the frequency domain.
I just received a pair of custom pulsers which produce a 1 MHz square wave instead of the standard 10 MHz. I wanted these to allow using a cheap DSO for TDR work.
I'll test them and compare the BNC to SMA connection against the 20 ps calibrator output of my Tek 11801.
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I do not understand. 80 gigasamples per second is not enough? This is a two-fold reserve from the Nyquist frequency.
You incorrectly apply the Nyquist Theorem. It depends on what you want to do. In this case, you have only 4-5 sample points on the rising edge, but at least 10 is recommended for reliable measurements: https://blog.teledynelecroy.com/2016/09/how-does-sampling-rate-affect-esd-pulse.html
I set the thresholds exactly as you described. And then stretched the signal.
OK. No problems. Look at the bottom left for the numbers that Lecroy counted automatically.
You should not have reduced the acquisition area to such an extent, since automatic measurements are made in the range of the captured image.
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Yeah you need enough definition in the edge to reliably find the 90% and 10% marks. Often the waveform is particularly curvy there so just linear interpolation could be off quite a bit.
Theoreticaly you could use sin(x)/x interpolation to reconstruct the area between the points as long as you meet the f/2 Nyquist requirement to get a perfect representation of the waveform between the points, thus letting you pick that magical 90% point reliably. However this only works if there is a brick wall filter at f/2. Oscilloscopes however have all sorts of different high frequency rolloff responses in there AFE (There are pros and cons to different ones too). Because of this the usual sin(x)/x interpolation won't be completely accurate (but still likely quite a bit closer to the real thing than linear interpolation). Dave recently did a good video related to this on scope interpolation.
So this is why its nice to have more points. For repeating waveforms such as this pulse generator its easy to get around the ADC sampling rate limitation by just turning on equivalent time sampling. This captures multiple edges and uses extra phase information from the trigger circuitry to determine the exact transition so that the scope can then merge the points together into single waveform with 100s of times more points, getting you a nice non-jaggy image of that edge. You do get some extra fuzziness because the trigger circuitry has some inherent amplitude and phase noise, the ADC clock has some amount of phase noise and the input signal has some noise in itself, but this can be easily taken care of using some averaging.
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You incorrectly apply the Nyquist Theorem. It depends on what you want to do. In this case, you have only 4-5 sample points on the rising edge, but at least 10 is recommended for reliable measurements: https://blog.teledynelecroy.com/2016/09/how-does-sampling-rate-affect-esd-pulse.html
I quite well understand the Nyquist theorem. And by itself, if we want to see the shape of the pulse front, we should have a tenfold frequency margin at a minimum. Those. if we want to consider a square wave of 1Hz, we need an oscilloscope with a sampling frequency > 20 Hz.
However, if we want to EVALUATE the bandwidth of the oscilloscope, then we do not need such a large stock. Again, the input from the pulser has a lower frequency than the input frequency of the oscilloscope. Approximately 0.35 / 0.034 = 10 GHz. This means 8 points per maximum signal frequency.
But if you are interested in looking at the details of the front, i can turn on the desired mode.
I set the thresholds exactly as you described. And then stretched the signal.
You should not have reduced the acquisition area to such an extent, since automatic measurements are made in the range of the captured image.[/quote]Yes, maybe I did not take into account this nuance in his work. I will retake the data.
For repeating waveforms such as this pulse generator its easy to get around the ADC sampling rate limitation by just turning on equivalent time sampling.
Yes, without a doubt. I did just quick measurements about the same as all the others in the subject. And I don’t really understand what caused such a great interest in my pictures? What would you like to see? I am sure that any further refinements will not greatly change the picture on the screen.
So what exactly do you expect to see in the picture?
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New pictures.
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This is the "world's fastest" Hantek DSO5062B (hacked and modified by forum user tatus1969):
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=787350;image)
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=787356;image)
in comparison to a plain vanilla Tek TPS2024
(https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/?action=dlattach;attach=787362;image)
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I could swear my unmodified Hantek 5102B managed 1.7ns with just a software unlock and tatus1969 claimed that he got his down to 1.5ns.
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I could swear my unmodified Hantek 5102B managed 1.7ns with just a software unlock and tatus1969 claimed that he got his down to 1.5ns.
Confirmed, he made some "special" terminators, using one of these, I can achieve 1.5ns. The above measurement was taken with a standard 50 Ohm inline terminator attached between the pulse generator and the scope.
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:-+ Bought one of these pulse generators from Leo, thanks! Splurged for fastest 2.92mm version (and had to buy $70 adapter separately, I'd wish there would a version in shop to include proper 2.92mm adapter, instead of cheap SMA).
(https://xdevs.com/doc/Leo/img/leo_fpg_1.jpg)
(https://xdevs.com/doc/Leo/img/leo_fpg_face_1.jpg) (https://xdevs.com/doc/Leo/img/leo_bot_1.jpg)
(https://xdevs.com/doc/Leo/img/leo_k_k_1.jpg) (https://xdevs.com/doc/Leo/img/leo_adapt_1.jpg)
Here are some quick and dirty results:
Tek DSA71604C
(https://xdevs.com/doc/Tektronix/DSA70000/imgtest_16g/fall_dsa16k.gif)
(https://xdevs.com/doc/Leo/test_dsa71604c/dpo_rise_ch1_16g_1.jpg)
Tek TDS7704B
(https://xdevs.com/doc/Tektronix/TDS7704B/test/tds7704b_lpg_1.jpg)
Tek DPO7254C
(https://xdevs.com/doc/Tektronix/DPO7254C/dpo7254c_rise_1.jpg) (https://xdevs.com/doc/Tektronix/DPO7254C/dpo7254c_rise.jpg) (https://xdevs.com/doc/Tektronix/DPO7254C/dpo7254c_conn_1.jpg)
Tek MDO4054C
(https://xdevs.com/doc/Tektronix/MDO4000C/test/leo/mdo4054c_fall_1.jpg)
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My 11801 calibrator and my SD-24 head will beat Leo's pulser, but only by a few ps.
I think Leo's pulsers are fantastic. I've got the standard 10 MHz plus a 100 ps impulse and a 1 MHz square wave custom all in BNC. I'll add an impulse in 3.5 mm if Leo will oblige and can beat the 100 ps BNC version.
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A long story with HP 54750A.
It came from scrap containers, without plugin.
Plugin for him is expensive and it is why, i make sales-offer with ihm her. Nobody wants him.
It should parted out and trow away, at this weeked. Because, it stands over one years and i am needed place.
But i found few days ago a cheap plugin (unchecked , mechanically cracked front)
Plugin has also eletrically damage, 2 regulator are getting very hot, a tantalium capactor is shorted. Replaced and "space ship" came to live. (a friends from me call ihm "space ship")
Test-Pulser is of coruse: Bodnar's Pulsgenerator, BNC-variant.
[attach=1]
[attach=2]
Regards
Matt
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hi. anyone has any idea what happened to leo bodnar? i tried to contact him through his website more than 24hrs ago, no reply. his last post is 2 months ago i hope he dont get caught by something nasty such as covid-19.. i try to get his BNC pulser, anyone want to resell? (faster sma will be better.. at half price :P) so long its still within spec.
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Simon is taking orders and responding to support emails.
A friend just bought the BNC version.
Have Fun!
Reg
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i dont see its sold in his website.. here linking his signature again https://simonselectronics.co.uk/ its just hard to find him in posts search there are many Simon out here, i believe you mean Simon the moderator...
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Different Simon. The Simon I referred to works for Leo.
http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295 (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295)
They are quite fabulous. I have 3 versions 1 & 10 MHz square wave and 100 ps pulse.
Have Fun!
Reg
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thats the website i used to contact them in "Contact Us" tab. i try again anyway thanks. or maybe they are not entertained if order from Malaysia?
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hi. anyone has any idea what happened to leo bodnar? i tried to contact him through his website more than 24hrs ago, no reply. his last post is 2 months ago i hope he dont get caught by something nasty such as covid-19.. i try to get his BNC pulser, anyone want to resell? (faster sma will be better.. at half price :P) so long its still within spec.
Thanks for checking in,
We are still open for business like nothing happened.
Cheers!
Leo
thats the website i used to contact them in "Contact Us" tab.
P.S. I think I have replied to you earlier this morning.
I have tested a new batch just last week
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hiya Leo! glad to hear you. ok now i received your email, check your email again there is specific question i would like to ask (shipping cost) cheers.
edit: that 33ps screenshoot is for BNC version? i would love to faster sma version, but its double the price, so i think i will only get the BNC version. my scope is BNC-ready input anyway.
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hi Leo. please check your email. (ps: this msg should be auto destruct upon receive confirmation ;D)
"Mr. Bodnar, your mission, should you choose to accept it,..." [Cue music] :)
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I got it, thanks.
If anyone is wondering what on Earth is going on - we are trying to figure out why automated FedEx shipping quote is so high.
FedEx have increased prices [again] but it might be what it is. Some local areas have extra charge because they are outside their regular delivery zones.
Cheers
Leo
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I got it, thanks.
the deal is closed (check PM sir) cant wait for that little toy to arrive.
If anyone is wondering what on Earth is going on - we are trying to figure out why automated FedEx shipping quote is so high.
FedEx have increased prices [again] but it might be what it is. Some local areas have extra charge because they are outside their regular delivery zones.
Cheers
Leo
guestimating from experience... Fedex ~USD40 UK to MY for small letter is quite reasonable. i've paid > $300 for a boat anchor from US and some sellers charge $1000, not something i'm willing to pay. either they overcharge or some places courier agent charges nasty amount. like my place, i paid $100 DHL to CH to repair an equipment under warranty where DHL CH can charge less than half of that to send a bigger item to MY. so there is no fixed weight (volumetric) vs distance charge rate here.
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got it! unfortunately i guess our country needs to recover from covid pandemic thats probably why i got taxed + charges extra $40 for a tiny device :palm: anyway, i think this device is real... 100ps on SDA6000+LPA_BNC and 1.5ns on terminated Rigol DS1054Z. next.. i'll need to find a way to improve connection to my SDA6000's BMA input. my diy BMA-BNC shows similar performance as the Original Lecroy LPA-BNC 8)
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LPA_BNC
What does LPA_BNC do?
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LPA_BNC
What does LPA_BNC do?
BMA (ProLink) adapter for probes with BNC (ProBus) output https://www.digikey.my/product-detail/en/teledyne-lecroy/LPA-BNC/LPA-BNC-ND/4732810 (https://www.digikey.my/product-detail/en/teledyne-lecroy/LPA-BNC/LPA-BNC-ND/4732810)
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got it! unfortunately i guess our country needs to recover from covid pandemic thats probably why i got taxed + charges extra $40 for a tiny device :palm: anyway, i think this device is real... 100ps on SDA6000+LPA_BNC and 1.5ns on terminated Rigol DS1054Z. next.. i'll need to find a way to improve connection to my SDA6000's BMA input. my diy BMA-BNC shows similar performance as the Original Lecroy LPA-BNC 8)
Rise time should be measured in equivalent mode, not real time.
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Hi,
Just came across this interesting little device. Looks very useful, however, I wish it had a couple of extra features:
- Configurable frequency and duty cycle (e.g. by using the timers of the MCU). Will make it much more useful for TDR and other uses.
- USB-C instead of USB-B. USB-B is a bit bulky and old-school...
But I will likely buy one soon anyway :-)
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Unfortunately, variable frequency and duty cycle would increase the jitter making them less useful for the primary use case. USB-B has the great virtue of durability and there is no need to make these smaller.
I was able to get a couple of BNC units at 1 MHz instead of 10 MHz for TDR, but the nanoVNA has largely obsoleted them for TDR. I think you can still get 3.5 and 2.48 mm pulsers at 1 MHz by request.
For the price it's the best assessment of a scope front end you can get.
Have Fun!
Reg
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Unfortunately, variable frequency and duty cycle would increase the jitter making them less useful for the primary use case.
It would still meet its jitter specification by far (since there is none...) ;) Why would jitter make it less useful for scope characterization? It should not impact jitter betwen trigger output and pulse output anyway.
Also wished:
- Dual balanced inverted/non-inverted SMA output for precise skew measurement/compensation and 100 Ohms balanced TDR.
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When used on a sampling scope the jitter will mess up the waveform since the scope needs to sample the exact point on multiple pulses. Same reason for the SMA on the back of it, it provides a easy to get at trigger signal for these sampling scopes.
If you need differential then you could connect a balun to the output of it.
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When used on a sampling scope the jitter will mess up the waveform since the scope needs to sample the exact point on multiple pulses. Same reason for the SMA on the back of it, it provides a easy to get at trigger signal for these sampling scopes.
Yes, jitter between trigger and pulse will mess up the waveform on a sampling scope. But jitter on the clock before the trigger output should have no effect. It will only matter when performing clock recovery and trigging on the recovered clock instead of the signal itself.
What is the jitter performance of the current pulse generator?
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Leo will have to answer that. I should be able to measure it, but have not done so. And Leo is an EE. I'm not.
Each unit comes with a plot of the step response using a CSA803A & 40 GHz SD-30 sampling head. This is a very evil thing to do. It provoked me to get an 11801. I'm a retired seismic guy, so TDR is my natural environment. I've had more fun with the 11801 and an SD-24 than any other piece of T&M kit. After a year or two I finally broke down and bought an SD-30 which came Thursday.
Have Fun!
Reg
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It provoked me to get an 11801. I'm a retired seismic guy, so TDR is my natural environment. I've had more fun with the 11801 and an SD-24 than any other piece of T&M kit. After a year or two I finally broke down and bought an SD-30 which came Thursday.
Have Fun!
Reg
Indeed, fun is what it is all about 8) Nice piece of kit!
Most of the TDRs I have done have been 100 Ohm balanced, and I have fooled around with baluns, hybrids and whatnot. An expensive 4 channel VNA helps alot... But I can see that a "pocket pulse transmitter" could have been a nice and simple addition for measuring cable runs :-/O. Maybe I will get around to make one myself - it doesn't have to be 40ps rise time ;D
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The nanoVNA has TDR capability now. Hugen's new version, the H4, uses a '303 instead of the '103 part so there is more memory for features in addition to the 4" screen. I haven't installed DiSlord's FW yet, but will eventually.
I built a pulser long ago using an ECL line driver. I thought I'd failed miserably at the time, but I later discovered when the EE who gave me access to a 485 at work and I measured it, we forgot to terminate it with 50 ohms. IIRC when I measured it recently it was about 1.5 ns. That was my introduction to how critical layout is at RF.
Have Fun!
Reg
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I've tried this new pulser from Leo which is just looking great. But during test I noticed that the pulse is negative going. This is not ideal as my scope is only DC coupled and only positive. Is there a simple way to invert the output of this pulser to a positive DC pulse?
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Hello Europeans,
I was about to order one set to Leo but realized suddenly a possible higher cost issue due to BREXIT for my small french company. Has anybody (Germany, Spain, France...) purchased after 1st january 2021 the pulser, how did your country dealt with VAT, import duty taxes since the good comes from UK ?
Another question since I need to only test some of my TDSxxx oscilloscope (tekProbe-BNC input), it seems the BNC version is out of stock for a few months so if I decide to buy one generator, I need to pay quite an extra to get the SMA model then buy-add a SMA-BNC adapter provided by Leo.
Does anyone would have been any change done testing to check the different rise time difference of SMA model directly connected then with BNC adapter inserted from the SMA-pulser ?
Merci, Albert
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Hello Europeans,
I was about to order one set to Leo but realized suddenly a possible higher cost issue due to BREXIT for my small french company. Has anybody (Germany, Spain, France...) purchased after 1st january 2021 the pulser, how did your country dealt with VAT, import duty taxes since the good comes from UK ?
Another question since I need to only test some of my TDSxxx oscilloscope (tekProbe-BNC input), it seems the BNC version is out of stock for a few months so if I decide to buy one generator, I need to pay quite an extra to get the SMA model then buy-add a SMA-BNC adapter provided by Leo.
Does anyone would have been any change done testing to check the different rise time difference of SMA model directly connected then with BNC adapter inserted from the SMA-pulser ?
Merci, Albert
Albert,
Shariar did :
https://www.youtube.com/watch?v=T-G4OhWSyIo&feature=emb_logo (https://www.youtube.com/watch?v=T-G4OhWSyIo&feature=emb_logo)
Maybe that answers your question.. Although result will highly depend on quality od adapter...
Regards,
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Shariar did :
https://www.youtube.com/watch?v=T-G4OhWSyIo&feature=emb_logo (https://www.youtube.com/watch?v=T-G4OhWSyIo&feature=emb_logo)
Maybe that answers your question.. Although result will highly depend on quality od adapter...
Many thanks @2N3055 where the adapter would be ordered as well from Leo's website http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=125_126&products_id=304 (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=125_126&products_id=304) so no idea on how this matches with the SMA pulser but I'd expect or suspect loss or slower speed hence my hesitation to order besides the BREXIT nightmare now if we purchase T&M from UK
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Unless it is a high performance >1GHz scope the adapter probably won't matter very much at all since the scopes own rise time will still dominate.
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Well I do own a TDS794D which supposed to offer 2 GHz plus now I see one detail about Leo's SMA-BNC adapter, it will require another adaptor to actually fit my TDSxxx's BNC input. Maybe wisdom is wait for new stock of fast pulse with BNC and in the meantime, I'll figure the new import rules between UK and France.
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Ah 2 GHz might get into it a bit if the adapter is a particularly bad one. I do have both the BNC and SMA versions of this pulse generator. But i probably wouldn't be fair to compare them since the BNC one on mine is the older revision that is slightly slower.
Maybe i will dig them up sometime and compare, can do it on a 3.5GHz scope or a 20 GHz sampling scope.
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Shariar did :
Maybe that answers your question.. Although result will highly depend on quality od adapter...
Many thanks @2N3055 where the adapter would be ordered as well from Leo's website http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=125_126&products_id=304 (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=125_126&products_id=304) so no idea on how this matches with the SMA pulser but I'd expect or suspect loss or slower speed hence my hesitation to order besides the BREXIT nightmare now if we purchase T&M from UK
That adapter is good quality, but wrong gender for direct plug in to a scope...
Maybe something like this :
https://hr.mouser.com/ProductDetail/Pomona-Electronics/4288/?qs=4luskHXVU9Z9%252BIyNoZZ24Q%3D%3D (https://hr.mouser.com/ProductDetail/Pomona-Electronics/4288/?qs=4luskHXVU9Z9%252BIyNoZZ24Q%3D%3D)
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Here results from a Keysight DSO-X 2014A (100MHz, 2GS/s) hacked to a Keysight DSO-X 2024A (200MHz, 2GS/s). Measurements made by using the SMA version of Leo's pulser with a rise time of approx. 28ps and a SMA to BNC adapter:
With 50 Ohm termination 1.5ns (2nd and 4th picture), without 50 Ohm termination 1.8ns (1st and 3rd picture).
The device meets its spec regarding the analog bandwidth, even without a proper termination. :-+
Sorry for messing around the sequence of the pictures ::)
[attachimg=1][attachimg=2][attachimg=3]
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And here the result from a Tektronix TDS3034 (300MHz, 2.5GS/s) hacked to a Tektronix TDS3054 (500MHz, 5GS/s). Measurements made by using the SMA version of Leo's pulser with a rise time of approx. 28ps and a SMA to BNC adapter:
Rise time 603ps
The device clearly outreach its spec regarding the analog bandwidth. :-+
[attachimg=1]
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and last but not least the spectrum
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Hi, I am an EE but I worked only in IT field for decades. Now I have gray hairs and I want to spend time (for hobby) on my first love: electronics.
Last week I received the fast pulse generator.
First practical use: I want to use it to determine the real bandwidth of an oscilloscope using the BW (GHz) = 0.35 / rise-time (ns) formula.
Reading previous posts in this thread I have learned two hints to measure rise-time correctly:
1) set input impedance to 50 Ohm (if oscilloscope can change input impedance) or use a BNC 50 Ohm impedance adapter on oscilloscope input channel
2) don't use real time sampling. Instead, because the impulse is a 10MHz repetitive waveform try to use equivalent time sampling
Do I forgot something? Can someone put me in the right direction to do this measurement in the correct way?
Thank in advance.
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I'am using for digital scopes the formula BW = 0.4/Tr
If sampling time is small enough, there's no need for equivalent sampling, but usually it's necessary. At the end you need at least 5 to 8 sampling points within the rise time. But you should use averaging to remove effects of jitter and noise.
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Set the timebase to the fastest setting that still shows the full rise time. At least some scopes use the displayed trace to compute the rise time. So if the total rise takes place in less than one major division the accuracy of the reported rise time won't be all that good.
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And here the result from a Tektronix 2465B. Measurements made by using the SMA version of Leo's pulser with a rise time of approx. 28ps and a SMA to BNC adapter:
Measured Rise times inbetween 620ps and 660ps
The device clearly outreach its spec regarding the analog bandwidth. :-+
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And here the result from a Tektronix 2465B. Measurements made by using the SMA version of Leo's pulser with a rise time of approx. 28ps and a SMA to BNC adapter
Could you share the reference or model of where you purchased the specific SMA to BNC to match the SMA gender of Leo's pulser ?
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I bought those quite cheap ones:
High Quality 4PCS SMA to BNC Kit RF Coaxial Adapter Male Female Coax Connectors
https://www.ebay.de/itm/143598904411 (https://www.ebay.de/itm/143598904411)
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Another way to demonstrate the impact of a adapter is to add extra unnecessary adapters in between and see what it does to the rise time. If the extra adapters don't do much then that one adapter probably doesn't either.
I usually find that a cheap coax cable does more distortion to a signal than a cheep adapter. At in the high GHz digits a piece of cheep generic coax becomes a 20dB attenuator.
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The adapter usually gives an additional time delay of 20ps to 40ps, but it should not influence the rise time or give a significant attenuation.
When I find some time I'll measure it with my VNA.
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Finally the BNC version was available again from stock so I've ordered one unit to Leo Bodnar from France.
Attached picture with 1st test ob my TDS784D, really amazing quality product which confirms the 1GHz bandwidth.
Will try later on my TDS794D and the strange TDS784C which I believe to rather be TDS754C (eBay seller left the 4 attenuators capacitors and modified the 4 resistors).
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I also just received one from the new stock.
I wanted it to check my DSO7000 scope out after modifying the input circuits so the BNC one was plenty fast enough (in fact, Leo's calibration showed this sample to be well beyond spec).
The first thing I tried it on was my HP53310A - I'd heard theat it could be used to make fast risetime measurements. But I got very strange results, with triggers failing and time measurements that were for the period rather than the risetime.
I eventually realised that it's just too damn fast for the 53310A which can only resolve about 70ps - the risetime is shorter than the uncertainty in the trigger propagation.
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The first thing I tried it on was my HP53310A - I'd heard theat it could be used to make fast risetime measurements. But I got very strange results, with triggers failing and time measurements that were for the period rather than the risetime.
Setting the threshold levels is critical, and without that you measure the period. Have a look at this thread https://www.eevblog.com/forum/testgear/hpagilent-53310a-modulation-domain-analyser-frequency-time-interval-analyser/msg3196908/#msg3196908 (https://www.eevblog.com/forum/testgear/hpagilent-53310a-modulation-domain-analyser-frequency-time-interval-analyser/msg3196908/#msg3196908)
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Albert,
Shariar did :
https://www.youtube.com/watch?v=T-G4OhWSyIo&feature=emb_logo (https://www.youtube.com/watch?v=T-G4OhWSyIo&feature=emb_logo)
That is pure scope porn.
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Now tested with my reconditioned TDS794D...
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I don't remember if the contest here is 80/20 proximal/distal or 90/10? Might have them reversed. With Leo's at 80/20 I'm getting less than 30ps at 80/20.
See that's the problem with this thread, you end up with a scope (or two if I get my 8000 running) that has almost no practical purpose for verifying anything other than oc192 comm lines. Note I said verifying because the carrier will fix it. Or you can play around looking for little bumps in coax lines... :-DD
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I don't remember if the contest here is 80/20 proximal/distal or 90/10? Might have them reversed. With Leo's at 80/20 I'm getting less than 30ps at 80/20.
See that's the problem with this thread, you end up with a scope (or two if I get my 8000 running) that has almost no practical purpose for verifying anything other than oc192 comm lines. Note I said verifying because the carrier will fix it. Or you can play around looking for little bumps in coax lines... :-DD
Doesn't the "o" stand for "optical"? I have an optical sampling head somewhere...
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An old project I found and decided to investigate.
This is not in the same class as Leo's, but it turns out it achieved the goal, though I couldn't tell it at the time. IIRC this is the 2nd iteration, but it was 30 years ago. I needed a <1 ns rise time step to adjust the front end of my 465 and Dumont 1062. At the time I thought I had failed, but I simply didn't have the tools to adjust it. I then found a cheap Tek 106 and used that.
My 11801/SD-26 did a great job using a DL-11 I just got. I've got an RC circuit to adjust the edge. Initially it was OK at 2-3 ns, but a bit of twiddle and I got the rise time under 1 ns.
Have Fun!
Reg
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man what a neck bending task, you must live somewhere 90 degree from me... btw.. reminds me that in case anyone doesnt have a FG yet, or just want to get another one as TEA collection, the synch signal of UTG962/932 can give another sub ps risetime... fwiw... https://www.eevblog.com/forum/testgear/uni-t-utg932utg962-200msas-function-arbitrary-waveform-generator-220394/msg2927402/#msg2927402 (https://www.eevblog.com/forum/testgear/uni-t-utg932utg962-200msas-function-arbitrary-waveform-generator-220394/msg2927402/#msg2927402)
(https://www.eevblog.com/forum/testgear/uni-t-utg932utg962-200msas-function-arbitrary-waveform-generator-220394/?action=dlattach;attach=931056;image)
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I don't remember if the contest here is 80/20 proximal/distal or 90/10? Might have them reversed. With Leo's at 80/20 I'm getting less than 30ps at 80/20.
Digital communication industry usually uses 80/20 and normal/analogue people - 90/10.
My rule is "it's 90/10, unless explicitly stated that it's 80/20". It's sensible, conservative and avoids spec inflation.
Cheers
Leo
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I don't remember if the contest here is 80/20 proximal/distal or 90/10? Might have them reversed. With Leo's at 80/20 I'm getting less than 30ps at 80/20.
Digital communication industry usually uses 80/20 and normal/analogue people - 90/10.
My rule is "it's 90/10, unless explicitly stated that it's 80/20". It's sensible, conservative and avoids spec inflation.
At higher frequencies and when cable lengths are longer, transmission line "dribble-up" prevents 90/10 measurements from being useful.
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I just received my BNC version pulse generator. Didn't expect it so soon. Invoice 2/10, arrived in US 2/19 for $7.74 shipping. Put it on a LeCroy HDO6104 1 Gz. Rise is measuring 479 psec (10/90). Should be faster.
... Chan 2 the same. Would be more disappointed if it was my scope. I've been storing it for someone for years. At some point it migrated to the primary scope spot on my bench.
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I just received my BNC version pulse generator. Didn't expect it so soon. Invoice 2/10, arrived in US 2/19 for $7.74 shipping. Put it on a LeCroy HDO6104 1 Gz. Rise is measuring 479 psec (10/90). Should be faster.
... Chan 2 the same. Would be more disappointed if it was my scope. I've been storing it for someone for years. At some point it migrated to the primary scope spot on my bench.
That's about right.
SDS5104X is ~400ps too.....faster scope required to resolve a faster risetime. ;)
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I just received my BNC version pulse generator. Didn't expect it so soon. Invoice 2/10, arrived in US 2/19 for $7.74 shipping. Put it on a LeCroy HDO6104 1 Gz. Rise is measuring 479 psec (10/90). Should be faster.
... Chan 2 the same. Would be more disappointed if it was my scope. I've been storing it for someone for years. At some point it migrated to the primary scope spot on my bench.
That's about right.
SDS5104X is ~400ps too.....faster scope required to resolve a faster risetime. ;)
Using the RT*BW=0.35 (or 0.45) I calculate 731 MHz (0.35) and 939 MHz (0.45). Both shy of 1GHz. Sampling rate of this scope is 2.5 GHz.
Measured a HP 54602B. This thing is terrible for fast one shot captures since it samples once per fortnight, but it does have the advertised BW. Stated 150 MHz; more like 200 MHz.
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I just received my BNC version pulse generator. Didn't expect it so soon. Invoice 2/10, arrived in US 2/19 for $7.74 shipping. Put it on a LeCroy HDO6104 1 Gz. Rise is measuring 479 psec (10/90). Should be faster.
... Chan 2 the same. Would be more disappointed if it was my scope. I've been storing it for someone for years. At some point it migrated to the primary scope spot on my bench.
That's about right.
SDS5104X is ~400ps too.....faster scope required to resolve a faster risetime. ;)
Using the RT*BW=0.35 (or 0.45) I calculate 731 MHz (0.35) and 939 MHz (0.45). Both shy of 1GHz. Sampling rate of this scope is 2.5 GHz.
Measured a HP 54602B. This thing is terrible for fast one shot captures since it samples once per fortnight, but it does have the advertised BW. Stated 150 MHz; more like 200 MHz.
For many years now, we have been saying that risetime of modern scope is not exactly correlated with BW with any simple ratio.
BW is determined with frequency sweep. Risetime is separate parameter and is specified independently.
Your scope has specification of 450ps 10-90% typical. Typical means it can be a bit better or worse and still be in spec. Also keep in mind risetime will vary with sensitivity and signal amplitude. At different sensitivities different combinations of attenuators and amplifier stages are switched in, making subtle changes in front end response.
Similar Siglent SDS6104H12 shows 410-415ps 10-90% risetime. So a bit better but that is with 5GSa/s.
When 2.5GSa/s is forced it shows 420-430ps. Same signal source, of course.
I would say it is just fine.
Leo ships pulsers with certificate where you can see exact risetimes and pulse shape.
Each one is individually characterized. He does fantastic job and gives superb service.
It is amazing the amount of effort and care he puts in such a simple and inexpensive device.
I wish there were more people like him in the business...
And no, no relations, just a happy customer.
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I just received my BNC version pulse generator. Didn't expect it so soon. Invoice 2/10, arrived in US 2/19 for $7.74 shipping. Put it on a LeCroy HDO6104 1 Gz. Rise is measuring 479 psec (10/90). Should be faster.
... Chan 2 the same. Would be more disappointed if it was my scope. I've been storing it for someone for years. At some point it migrated to the primary scope spot on my bench.
That's about right.
SDS5104X is ~400ps too.....faster scope required to resolve a faster risetime. ;)
Using the RT*BW=0.35 (or 0.45) I calculate 731 MHz (0.35) and 939 MHz (0.45). Both shy of 1GHz. Sampling rate of this scope is 2.5 GHz.
Now with a moment to hunt out a previously captured screenshot with Leo's pulser on 5 GSa/s SDS5104X.
IIRC this pulser had a spec of 30ps risetime.
(https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/?action=dlattach;attach=1302860)
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I just received my BNC version pulse generator. Didn't expect it so soon. Invoice 2/10, arrived in US 2/19 for $7.74 shipping. Put it on a LeCroy HDO6104 1 Gz. Rise is measuring 479 psec (10/90). Should be faster.
... Chan 2 the same. Would be more disappointed if it was my scope. I've been storing it for someone for years. At some point it migrated to the primary scope spot on my bench.
That's about right.
SDS5104X is ~400ps too.....faster scope required to resolve a faster risetime. ;)
Using the RT*BW=0.35 (or 0.45) I calculate 731 MHz (0.35) and 939 MHz (0.45). Both shy of 1GHz. Sampling rate of this scope is 2.5 GHz.
Measured a HP 54602B. This thing is terrible for fast one shot captures since it samples once per fortnight, but it does have the advertised BW. Stated 150 MHz; more like 200 MHz.
For many years now, we have been saying that risetime of modern scope is not exactly correlated with BW with any simple ratio.
BW is determined with frequency sweep. Risetime is separate parameter and is specified independently.
Your scope has specification of 450ps 10-90% typical. Typical means it can be a bit better or worse and still be in spec. Also keep in mind risetime will vary with sensitivity and signal amplitude. At different sensitivities different combinations of attenuators and amplifier stages are switched in, making subtle changes in front end response.
Similar Siglent SDS6104H12 shows 410-415ps 10-90% risetime. So a bit better but that is with 5GSa/s.
When 2.5GSa/s is forced it shows 420-430ps. Same signal source, of course.
I would say it is just fine.
Leo ships pulsers with certificate where you can see exact risetimes and pulse shape.
Each one is individually characterized. He does fantastic job and gives superb service.
It is amazing the amount of effort and care he puts in such a simple and inexpensive device.
I wish there were more people like him in the business...
And no, no relations, just a happy customer.
I agree 100% about Leo. I don't really need this thing to measure my scope front ends, it was just the first thing I did when I got the pulser. I just checked the LeCroy using a sig gen, and it was down 3 dB at 930 MHz which is in line with the estimate using risetime. I have VNA and SA to verify cable losses and signal levels. I've been toying with building a fast rise pulser, and with the price Leo has for his unit it just isn't worth my time. And if I did build something like his, I couldn't measure the actual risetime. Certificate with mine says 36.34 ps rise, 30.26 ps fall. I'm also a happy customer.
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I was so happy with Leo's pulse generator, I bought two more with different connectors and all three are performing very well.
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I designed a housing for Leo's pulse generator.
Printed it with a layer height of 0.1mm and infill grid pattern with a density of 33%. I attached the cover with a little bit of super glue.
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very nice.
I'll make one now :)
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I designed a housing for Leo's pulse generator.
Printed it with a layer height of 0.1mm and infill grid pattern with a density of 33%. I attached the cover with a little bit of super glue.
Thanks for making the housing.
I am getting bad dimensions.
Could you save the files to a STEP or IGIS file format?
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I have updated the post with CAD drawings.
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I have updated the post with CAD drawings.
Thanks, now all dimensions are imported correctly into Solidworks!
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I designed a housing for Leo's pulse generator.
Printed it with a layer height of 0.1mm and infill grid pattern with a density of 33%. I attached the cover with a little bit of super glue.
Nice work Tom. :-+
You could also post this housing info here:
https://www.eevblog.com/forum/testgear/replacement-knobs-feet-and-fittings-for-test-equipment/ (https://www.eevblog.com/forum/testgear/replacement-knobs-feet-and-fittings-for-test-equipment/)
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I got my LB generator last night am I'm very satisfied with it. :-+
To protect the SMD componets I printed a small housing for it and uploaded the STL file here:
https://www.eevblog.com/forum/testgear/gw-instek-mdo-2000e/msg1458487/#msg1458487 (https://www.eevblog.com/forum/testgear/gw-instek-mdo-2000e/msg1458487/#msg1458487)
My GW Instek MDO-2204EX has 1,22ns rise and fall time. Plenty fast for the work I do. :-/O
Let us give back to Cesar what belongs to Cesar...