Author Topic: Yet another fast edge pulse generator  (Read 98222 times)

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Online Mechatrommer

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Re: Yet another fast edge pulse generator
« Reply #550 on: June 26, 2020, 02:48:27 am »
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)
It's extremely difficult to start life.. one features of nature.. physical laws are mathematical theory of great beauty... You may wonder Why? our knowledge shows that nature is so constructed. We simply have to accept it. One could describe the situation by saying that... (Paul Dirac)
 

Offline exe

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Re: Yet another fast edge pulse generator
« Reply #551 on: June 26, 2020, 09:57:58 am »
 

Online Mechatrommer

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It's extremely difficult to start life.. one features of nature.. physical laws are mathematical theory of great beauty... You may wonder Why? our knowledge shows that nature is so constructed. We simply have to accept it. One could describe the situation by saying that... (Paul Dirac)
 

Offline Converter

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Re: Yet another fast edge pulse generator
« Reply #553 on: June 26, 2020, 02:24:06 pm »
got it! unfortunately i guess our country needs to recover from covid pandemic thats probably why i got taxed + charges extra $40 for a tiny device :palm: anyway, i think this device is real... 100ps on SDA6000+LPA_BNC and 1.5ns on terminated Rigol DS1054Z. next.. i'll need to find a way to improve connection to my SDA6000's BMA input. my diy BMA-BNC shows similar performance as the Original Lecroy LPA-BNC 8)
Rise time should be measured in equivalent mode, not real time.
 
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Online Vestom

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Re: Yet another fast edge pulse generator
« Reply #554 on: July 25, 2020, 10:29:09 pm »
Hi,
Just came across this interesting little device. Looks very useful, however, I wish it had a couple of extra features:
- Configurable frequency and duty cycle (e.g. by using the timers of the MCU). Will make it much more useful for TDR and other uses.
- USB-C instead of USB-B. USB-B is a bit bulky and old-school...

But I will likely buy one soon anyway :-)
 

Online rhb

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Re: Yet another fast edge pulse generator
« Reply #555 on: July 25, 2020, 11:35:52 pm »
Unfortunately, variable frequency and duty cycle would increase the jitter making them less useful for the primary use case.  USB-B has the great virtue of durability and there is no need to make these smaller.

I was able to get a couple of BNC units at 1 MHz instead of 10  MHz for TDR, but the nanoVNA has largely obsoleted them for TDR.  I think you can still get 3.5 and 2.48 mm pulsers at 1 MHz by request.

For the price it's the best assessment of a scope front end you can get.

Have Fun!
Reg
 

Online Vestom

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Re: Yet another fast edge pulse generator
« Reply #556 on: July 26, 2020, 12:26:11 am »
Unfortunately, variable frequency and duty cycle would increase the jitter making them less useful for the primary use case. 
It would still meet its jitter specification by far (since there is none...) ;) Why would jitter make it less useful for scope characterization? It should not impact jitter betwen trigger output and pulse output anyway.

Also wished:
- Dual balanced inverted/non-inverted SMA output for precise skew measurement/compensation and 100 Ohms balanced TDR.
 

Online Berni

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Re: Yet another fast edge pulse generator
« Reply #557 on: July 26, 2020, 06:48:41 am »
When used on a sampling scope the jitter will mess up the waveform since the scope needs to sample the exact point on multiple pulses. Same reason for the SMA on the back of it, it provides a easy to get at trigger signal for these sampling scopes.

If you need differential then you could connect a balun to the output of it.
 

Online Vestom

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Re: Yet another fast edge pulse generator
« Reply #558 on: July 26, 2020, 08:14:09 am »
When used on a sampling scope the jitter will mess up the waveform since the scope needs to sample the exact point on multiple pulses. Same reason for the SMA on the back of it, it provides a easy to get at trigger signal for these sampling scopes.
Yes, jitter between trigger and pulse will mess up the waveform on a sampling scope. But jitter on the clock before the trigger output should have no effect. It will only matter when performing clock recovery and trigging on the recovered clock instead of the signal itself.

What is the jitter performance of the current pulse generator?
 

Online rhb

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Re: Yet another fast edge pulse generator
« Reply #559 on: July 26, 2020, 01:10:15 pm »
Leo will have to answer that.  I should be able to measure it, but have not done so.  And Leo is  an EE.  I'm not.

Each unit comes with a plot of the step response using a CSA803A & 40 GHz SD-30 sampling head.  This is a very evil thing to do.  It provoked me to get an 11801.  I'm a retired seismic guy, so TDR is my natural environment.  I've had more fun with the 11801 and an SD-24 than any other piece of T&M kit.  After a year or two I finally broke down and bought an SD-30 which came Thursday.

Have Fun!
Reg
 

Online Vestom

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Re: Yet another fast edge pulse generator
« Reply #560 on: July 26, 2020, 07:24:25 pm »
It provoked me to get an 11801.  I'm a retired seismic guy, so TDR is my natural environment.  I've had more fun with the 11801 and an SD-24 than any other piece of T&M kit.  After a year or two I finally broke down and bought an SD-30 which came Thursday.

Have Fun!
Reg
Indeed, fun is what it is all about 8) Nice piece of kit!

Most of the TDRs I have done have been 100 Ohm balanced, and I have fooled around with baluns, hybrids and whatnot. An expensive 4 channel VNA helps alot... But I can see that a "pocket pulse transmitter" could have been a nice and simple addition for measuring cable runs  :-/O. Maybe I will get around to make one myself - it doesn't have to be 40ps rise time ;D
 

Online rhb

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Re: Yet another fast edge pulse generator
« Reply #561 on: July 28, 2020, 12:45:18 pm »
The nanoVNA has TDR capability now.  Hugen's new version, the H4, uses a '303 instead of the '103 part so there is more memory for features in addition to the 4" screen.  I haven't installed DiSlord's FW yet, but will eventually.

I built a pulser long ago using an ECL line driver.  I thought I'd failed miserably at the time, but I later discovered when the EE who gave  me access to a 485 at work and I measured it, we forgot to terminate it with 50 ohms.  IIRC when I measured it recently it was about 1.5 ns.  That was my introduction to how critical layout is at RF.

Have Fun!
Reg
 


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