Yet another fast edge pulse generator

[2N3055]

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 ..
Thanks for pointing it out.
On two second ones he has quite a spread between minimum and maximum values, probably something wrong with connection.

[MegaVolt]

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.

[Converter]

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?).

[MegaVolt]

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.

[rhb]

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.

[Converter]

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.

[Berni]

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.

[MegaVolt]

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?

[MegaVolt]

New pictures.

[capt bullshot]

This is the "world's fastest" Hantek DSO5062B (hacked and modified by forum user tatus1969):




in comparison to a plain vanilla Tek TPS2024

[magic]

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.

[capt bullshot]

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.

[TiN]

  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).







Here are some quick and dirty results:

Tek DSA71604C





Tek TDS7704B



Tek DPO7254C



Tek MDO4054C

[rhb]

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.

[madao]

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.


Regards
Matt

[Mechatrommer]

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 ) so long its still within spec.

[rhb]

Simon is taking orders and responding to support emails.

A friend just bought the BNC version.

Have Fun!
Reg

[Mechatrommer]

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...

[rhb]

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

They are quite fabulous. I have 3 versions 1 & 10 MHz square wave and 100 ps pulse.

Have Fun!
Reg

[Mechatrommer]

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?

[Leo Bodnar]

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 ) 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

[Mechatrommer]

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.

[Cerebus]

hi Leo. please check your email. (ps: this msg should be auto destruct upon receive confirmation )

"Mr. Bodnar, your mission, should you choose to accept it,..."  [Cue music] 

[Leo Bodnar]

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

[Mechatrommer]

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.