Author Topic: Is this product a BS didn't it?  (Read 3290 times)

0 Members and 1 Guest are viewing this topic.

Offline Marco

  • Super Contributor
  • ***
  • Posts: 6694
  • Country: nl
Re: Is this product a BS didn't it?
« Reply #25 on: October 18, 2021, 04:51:56 pm »
Kinda sounds like it might not be a real high speed ADC measurement, but more of an implied result based on comparator threshold measurements maybe?
At the claimed 12.8GHz you'd need some insanely fast ADC stuff to get a real time eye diagram. I'm not seeing that capability on that board.
An ultrafast comparator with fast latching can do the equivalent of ADC on a repetetive signal. Equivalent equivalent time sampling so to say :)
 

Offline BrianHG

  • Super Contributor
  • ***
  • Posts: 7660
  • Country: ca
Re: Is this product a BS didn't it?
« Reply #26 on: October 18, 2021, 05:18:28 pm »
Speaking of repetitive sampling techniques on a fixed pattern generator, don't ADCs exist, not necessarily too high a sampling frequency, but, a super small sample-and-hold gate at the input down in the 100ps range?  All you need is a 100-200MHz sampling rate, but, a ~100ps sample-and-hold.  In fact, the sample and hold may also be an external stand-alone IC.

 

Offline Marco

  • Super Contributor
  • ***
  • Posts: 6694
  • Country: nl
Re: Is this product a BS didn't it?
« Reply #27 on: October 18, 2021, 05:31:43 pm »
The only advantage over the dac+comparator approach is speed, which is not all that important. Not worth paying the 100x boutique price multiplier for.
 

Online langwadt

  • Super Contributor
  • ***
  • Posts: 4392
  • Country: dk
Re: Is this product a BS didn't it?
« Reply #28 on: October 18, 2021, 06:42:17 pm »
Speaking of repetitive sampling techniques on a fixed pattern generator, don't ADCs exist, not necessarily too high a sampling frequency, but, a super small sample-and-hold gate at the input down in the 100ps range?  All you need is a 100-200MHz sampling rate, but, a ~100ps sample-and-hold.  In fact, the sample and hold may also be an external stand-alone IC.

you can get plenty of ADCs with far higher analog bandwidth and sample-hold than sample rate, so they can be used for subsampling, but once you get to GHz they get expensive

https://hackaday.io/project/167292-8-ghz-sampling-oscilloscope
« Last Edit: October 18, 2021, 10:11:54 pm by langwadt »
 

Offline Sal Ammoniac

  • Super Contributor
  • ***
  • Posts: 1663
  • Country: us
Re: Is this product a BS didn't it?
« Reply #29 on: October 18, 2021, 08:09:01 pm »
TotalPhase products are solid.

I would agree that their hardware is generally solid, but their software often leaves much to be desired. I have one of their instruments, and the software application that goes with it crashes after 2-3 days of collecting data. Since I use this device to debug intermittent issues that occur infrequently, this makes it useless. I reported this issue to the company years ago, but it still hasn't been fixed.
Complexity is the number-one enemy of high-quality code.
 

Online vaualbusTopic starter

  • Frequent Contributor
  • **
  • Posts: 352
  • Country: it
Re: Is this product a BS didn't it?
« Reply #30 on: October 18, 2021, 08:19:20 pm »
 Yeah that is also true Indeed
 

Online EEVblog

  • Administrator
  • *****
  • Posts: 37661
  • Country: au
    • EEVblog
Re: Is this product a BS didn't it?
« Reply #31 on: October 18, 2021, 10:15:03 pm »
It's true that jitter is an issue for ETS but if this is dedicated for measuring high speed links you would be able to use the clock/data recovery circuit within your receiver to provide a low jitter trigger. 

Some FPGAs have a built in eye scan capability as described here: https://wiki.analog.com/resources/tools-software/linux-software/jesd_eye_scan

That's very cool. That is almost certainly how they are doing it.
This actually opens the door for a very cheap version of this product that does exactly the same thing.
https://www.xilinx.com/support/documentation/application_notes/xapp743-eye-scan-mb-mcs.pdf
« Last Edit: October 18, 2021, 10:17:19 pm by EEVblog »
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf