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?
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'll be happy to build a few for sale if this is something useful to others.
Leo
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.
I'd be amazed if the world market is that huge. But stranger things happened :)
Leo
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?
I'd be amazed if the world market is that huge. But stranger things happened :)
Pre-trigger would need another connector.
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?
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?Fully assembled, tested and ready to go unit.
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
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
Thank You! We Appreciate your Business!
Your Order Number is: 20498
If you build some, I am interested in buying one.
I'll be happy to build a few for sale if this is something useful to others.
Leo
Cheers, guys. This is probably an ultimate case of impulse buying.Impulse buying? Never! you can't measure risetime with an impulse :P
Thank You! We Appreciate your Business!
Your Order Number is: 20505Also 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.
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?
Hi Leo,
Just ordered one on your website.
Could you provide the schematics ?
Thanks
Jacques
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
Where do I find the website ?
This device will add a few entries into the 'Show us your square wave' thread.
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...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.
@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 :)
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.
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.
Your pulse generator arrived today in Germany, thanks for the fast shipment.It looks like a decimal dot/comma confusion.
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
Today mine arrived. I guess my TDS580 wins the prize for the most ringing display
Now tested on my Agilent MSO 7045B 500 MHz scopeDon't forget to terminate input to 50R if you want fastest and cleanest risetime.
Rise Time 1.03 ns
No overshoot, may be the scope is too slow!
Now tested on my Agilent MSO 7045B 500 MHz scopeDon't forget to terminate input to 50R if you want fastest and cleanest risetime.
Rise Time 1.03 ns
No overshoot, may be the scope is too slow!
Leo
Now my last scope for this test, a Keysight MSO-X-6004A, 6 GHz, 50 OhmAssuming total system risetime Tsystem2 = Tscope2 + Tpulser2
Rise time is 88 ps
Neat to see some CROs join in even if they are hybrids.
Oh and do all your scopes have names like that?
Found some time and tried the Wavewhatever MX104 @work
Hi Leo,Hi Denis,
News from order 20535?
Do I see this right, the Tektronix 2GHz MSO58 has 213 ps rise time with this 50ps pulse generator ?
Received mine today as hoped.Cheers,
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).
I have modified the configuration software to fix the decimal comma/point issue for locales that use decimal comma.
we can't change it. All of our test devices needs point separator for communication
I just started a Google spreadsheet and added what's been posted in this thread so far. See attached screenshot.I'd make the default sort order manufacturer and then model.
Any suggested changes before I try to make it public (never made a shared one before)? What should we call it?
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?
Any suggested changes before I try to make it public (never made a shared one before)? What should we call it?
Now my last scope for this test, a Keysight MSO-X-6004A, 6 GHz, 50 OhmAssuming total system risetime Tsystem2 = Tscope2 + Tpulser2
Rise time is 88 ps
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.
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 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?
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
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.
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
Still making these? I missed the thread initially but would love to buy one!Sure, I have them in stock.
Still making these? I missed the thread initially but would love to buy one!
But I do want to comment on how professionally made and packed the device was. Wow!
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.
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.All units are quite consistent in their parameters - within 1-2% overshoot and ±4ps risetime.
Is that possible that you pre-select one?
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.
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.All units are quite consistent in their parameters - within 1-2% overshoot and ±4ps risetime.
Is that possible that you pre-select one?
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
At the moment I only have 20GHz SD-26, 12.5GHz SD-22 and 3GHz WavePro 7300A to go by.
Leo
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)
Get yours here. (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295)
QuoteHere 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-
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.
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?
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."
Perfect!GETDo you need a picture to go with that? :)
~IT~
HERE (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295)
(http://www.bbc.co.uk/staticarchive/8d699778fc7c07a52e7516e29e392322f9051e4a.jpg) (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295)
Try setting the scope to "talk only" if possible to drive a plotter.
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.
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.
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.
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?
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.
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.
Maybe I missed it, but which output driver (the one branded AJK BAA) are you using in the latest revision?MAX3949
I received mine today!
Are all the measurements being done here 10%/90% or 20%/80% ?
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.
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.)
[/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.
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
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 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
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 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.I accept your reasoning but I had problems with people not being able to find suitable USB cable locally.
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
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
Looks like I'd have to make and stock SMA version as well at some point.
Leo
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?
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.
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.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.
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?Thanks to KE5FX and his software - I did not have a proper chance to say how good and useful his stuff is!
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
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.
Agilent 54622D 100MHz 200MS/s: Avg rise time 7.47 nsThat seems slow for a 100MHz 'scope - should be around 3.5ns?
Works great! Thank you, Leo! :-+
That seems slow for a 100MHz 'scope - should be around 3.5ns?
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).
..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.
LeCroy J-250 1GHz 16GS/s (WavePro 950): Avg rise time 0.246 ns, Single-shot acquisition
..
Works great! Thank you, Leo! :-+
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)?
I must try this with the 950, though I know it only has the "vanilla" FFTCan 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.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.
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.Current revision is Rev.G and I have modified power bypass quite a lot. So the short answer is "tricky" :)
Is this something that I can retrofit on the old board or would that be too tricky?
:)
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)
I must try this with the 950......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.
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.
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
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.
No and I suspect that might have something to do with the response.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?
I have a home made 50 ohm pass-through somewhere - I might dig it out.....
hey LeoHiya,
Are you thinking the design iterations are pretty much done now?
hey LeoHiya,
Are you thinking the design iterations are pretty much done now?
Pretty much so.
Pulser performance went beyond what I originally wanted it to do. It even has an LED now.
Cheers
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.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)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.
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 would buy another one of these if a SMA version becomes available.
OK Leo, order 23042 inThank you for your order, it has shipped today.
Thank you and have a good holiday!
Leo, thank you very much, my order arrived today.My pleasure! That was the older pulser model based on ADCMP***, its design has changed since then. Amplitude increased too.
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
...
cool project, thanks leo! :-+You are welcome!
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** :)
Has anyone come across any readily available good and cheap SMA(f) - BNC(m) adaptors? (not surplus expensive ones, but cheap when bought new)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.
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.
(http://media.digikey.com/Photos/Mueller%20Photos/MFG_BU-P4290_sml.jpg) (https://www.digikey.co.uk/products/en?keywords=314-1184-ND)
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.Thanks for the comparison. It seems even the cheapies are not too shabby.
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.
Has anyone tried any experiments using this device as a step source for TDR impedance measurements.
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.
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.
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.
Welcome to the club! :-)
Above the screen, under STORAGE, the print & setup keys, and their "blue-shifted" versions.
regards, Gerhard
Now that i got my 'new' sampling scope working and calibrated i also gave this fast pulser a test.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).
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.
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.:-+
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.33.99 ps? Okay, we will assume that 34ps.
If there is interest I can assemble few more pulsers with 2.92mm or SMA connectors and make them available for sale
I am interested in an SMA version also.
I have enough confidence in SMA/2.92mm version to offer it for sale now.
Interestingly, on the SMA Pulser-3, the waveform has shifted down by 500 mVSMA and 2.92mm versions are DC coupled and have negative going pulse.
More interesting, the very first one you made for me is the fastest right now.
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.
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
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.Yep, I noticed. You get to choose between fake dots or fake warranty when choosing a cheap scope.
1GHz is 35 ps, not 350 ps :D
1GHz is 35 ps, not 350 ps :D
Must be those newfangled metric picoseconds. :)
1GHz is 35 ps, not 350 ps :D
Must be those newfangled metric picoseconds. :)
* 14,238,992,130,000 inches per milli-fortnight.
Oops, not well awaken yesterday morning, sorry |O
* 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.
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.
Absolutely right.
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.
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.
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.Don't be disappointed, your figure of 436ps is about the same, as what I measured on my MSOX3104A
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.
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.
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. :)
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 can't see any reason that you could not let the user choose the step response.
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.
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.
You can never have enough scopes
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.
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)
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.
auto/manual are all dedicated buttons and i use them all the time
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)
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.)
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.
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)
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.
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)
Just a heads-up for anyone who has missed this - BNC versions are in stock for immediate shipment.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?)
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)
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).
Press Release (https://www.picotest.com/downloads/INJECTORS/Picotest%20Releases%20New%20PerfectPulse%20Signal%20Generator%20TDR_REV1_072618.pdf)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 :)QuoteContact 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)
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.With low volume specialist products the BOM cost quickly loses relevance.
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. :)
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.
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)
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?
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?
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? :)
Hi Leo!
Why do you use that chunky usb port, and not micro-usb / usb-c ?
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.
Those are blatantly hipster USB connectors!Usb C is supposedly more sturdy, but the proof is in the pudding.
This resistive splitter is way lower cost than I expected.And I recently bought some at a ridiculous price, so there was no point for fuss. :)
https://www.minicircuits.com/WebStore/dashboard.html?model=ZFRSC-183-S%2B (https://www.minicircuits.com/WebStore/dashboard.html?model=ZFRSC-183-S%2B)
2. PicoScope 5244B with and without ETS engaged
Any specific reason to use 0.45/RT not 0.35/RT for calculation?
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.QuoteAFAIK, 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."
I can't recall where exactly I got 0.45 coefficient from but quick search produces: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.
"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.
Any progress on this?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
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.
You need to use a bandwidth ten times more to try to find differences.
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
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.
This year the pulsers went to NASA, European Space Agency, Facebook, Tektronix, Rohde & Schwarz, many other T&M manufacturers and test labs.
Cheers, Tom. FB have hardware divisions.In the news today:https://mashable.com/article/facebook-disbands-building-8/#gnOeGAa03qqm (https://mashable.com/article/facebook-disbands-building-8/#gnOeGAa03qqm)
Leo
Any EEVBlog member discount for those who don't have FB/NASA-level deep pockets? ;)
The price already has any possible discounts in. NASA is just paying EEVBlog price, not the other way round.
Leo
When you see the wiggles BEFORE the edge you know it's DSP voodoo in action...
When you see the wiggles BEFORE the edge you know it's DSP voodoo in action...
That you can see the history before the trigger, that is old.
So, there is actually no pre-ringing, it's just an artifact of interpolation?That says it all:
So, there is actually no pre-ringing, it's just an artifact of interpolation?
If you follow the rabbit hole down far enough, you will meet a fellow named Heisenberg who isn't sure where the exit is.
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 two ideas are totally unrelated.
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.Werner says: "Trying to interpret a sentence might affect its meaning."
2) "No, they are not totally unrelated."
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.
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.
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.
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.
Heisenberg's principle relates the location of a particle to its velocity which is the time derivative of location.
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.
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. ;-)
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.
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.
I've got my pulsar two weeks ago. I must have to say, it is worth every penny for it.Thanks, TGyuri. Not that I am aware of! :)
...
May I ask, do you have hungarian ancestry?
MegaVolt, sorry, but what was it now?
What kind of fabulous sma adapter did you use?
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.
:palm:MegaVolt, sorry, but what was it now?
What kind of fabulous sma adapter did you use?
https://aliexpress.com/item/32831271535.html
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.
For a 3.5 GHz scope with BNC/SMA converter about 150 something psec sounds fine to me ..No, as far as I understood his message, in the last 2 screenshots he used the HF-input ProLink with the appropriate adapter.
It is 20GHz bandwidth scope but on ProLink inputs. He used ProBus input, that one has 3.5 GHz bandwidth...
For a 3.5 GHz scope with BNC/SMA converter about 150 something psec sounds fine to me ..No, as far as I understood his message, in the last 2 screenshots he used the HF-input ProLink with the appropriate adapter.
It is 20GHz bandwidth scope but on ProLink inputs. He used ProBus input, that one has 3.5 GHz bandwidth...
If it is not, let him correct.
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.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.
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.
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.
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.htmlI 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.
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.
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.
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,
thats the website i used to contact them in "Contact Us" tab.P.S. I think I have replied to you earlier this morning.
hi Leo. please check your email. (ps: this msg should be auto destruct upon receive confirmation ;D)
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.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.
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
LPA_BNC
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)LPA_BNCWhat does LPA_BNC do?
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.
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.
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.
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.Indeed, fun is what it is all about 8) Nice piece of kit!
Have Fun!
Reg
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
Shariar did :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
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...
Shariar did :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
Maybe that answers your question.. Although result will highly depend on quality od adapter...
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 adapterCould you share the reference or model of where you purchased the specific SMA to BNC to match the SMA gender of Leo's pulser ?
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.
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)
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
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.
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.
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.That's about right.
... 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.
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.That's about right.
... 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.
SDS5104X is ~400ps too.....faster scope required to resolve a faster risetime. ;)
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.That's about right.
... 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.
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.
Now with a moment to hunt out a previously captured screenshot with Leo's pulser on 5 GSa/s SDS5104X.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.That's about right.
... 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.
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.
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.That's about right.
... 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.
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 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.
I have updated the post with CAD drawings.
I designed a housing for Leo's pulse generator.Nice work Tom. :-+
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.
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