Products > Test Equipment

Pocket-Sized 6 GHz 1 TS/s ET Scope

<< < (44/107) > >>

SJL-Instruments:
Thanks for the detailed experiments. The noise level in the last three results are consistent with our test units. We have run a few temperature tests after the firmware update and saw nothing unusual, but it will be interesting to see your results.

Your results from #210 again rule out any timing issue (since CH1 is clean), and anything to do with the internal inversion (since CH4 behaves similarly to CH2, CH3).


--- Quote from: joeqsmith on January 31, 2024, 04:44:46 pm ---I plan to repeat these tests once your software has evolved.  Maybe that has something to do with it. 

--- End quote ---
We think the software is an unlikely culprit - all channels are processed in the same way at all delays.

joeqsmith:

--- Quote from: SJL-Instruments on January 31, 2024, 09:03:55 pm ---Thanks for the detailed experiments. The noise level in the last three results are consistent with our test units

--- End quote ---

No problem. Wish things would have repeated.  You can see from the first and last data sets how channel 1&4 matched up very close to the original data.   


--- Quote ---Your results from #210 again rule out any timing issue (since CH1 is clean), and anything to do with the internal inversion (since CH4 behaves similarly to CH2, CH3).
--- End quote ---

Signal generator is common across all 4 channels.  Doubt the 4 cables or splitter is bad. 


--- Quote ---We think the software is an unlikely culprit - all channels are processed in the same way at all delays.
--- End quote ---

Can you think of anything with the hardware that could cause this?  I'm not referring to the FPGA but the physical hardware like soldering, artwork, contamination.     

SJL-Instruments:

--- Quote from: joeqsmith on January 31, 2024, 10:05:16 pm ---Can you think of anything with the hardware that could cause this?  I'm not referring to the FPGA but the physical hardware like soldering, artwork, contamination.     

--- End quote ---
Nothing special happens in the hardware at 11.8 ns - a physical issue might cause a problem, but it's odd that the increased noise would only show up at one delay.

Your unit was from our first small-run batch (earmarked for test/review only). Since we improve our process and QA with each run, the first batch is also the most likely to have physical issues. We've sent you an email with more specifics on which chips/etc might cause a problem. But any physical issue we can think of would cause random spikes everywhere, not just at one time.

joeqsmith:

--- Quote from: SJL-Instruments on February 01, 2024, 01:45:28 am ---
--- Quote from: joeqsmith on January 31, 2024, 10:05:16 pm ---Can you think of anything with the hardware that could cause this?  I'm not referring to the FPGA but the physical hardware like soldering, artwork, contamination.     

--- End quote ---
Nothing special happens in the hardware at 11.8 ns - a physical issue might cause a problem, but it's odd that the increased noise would only show up at one delay.

Your unit was from our first small-run batch (earmarked for test/review only). Since we improve our process and QA with each run, the first batch is also the most likely to have physical issues. We've sent you an email with more specifics on which chips/etc might cause a problem. But any physical issue we can think of would cause random spikes everywhere, not just at one time.

--- End quote ---

Like all multifaceted problems, it takes time to peel away the layers of the onion.   I suspect we are not dealing with so much an 11.8ns time, but rather what was happening with the signal at that time.  When I attempted to measure channel 1's return loss, it was unstable.  Reworking the connector solved that.  Now, channel 1 appears to be the most stable.  After your updates to the FPGA and firmware, I have yet to see anything I would consider a glitch on that channel after several hours of testing. 

Upon further inspection, I have some concerns with the soldering which I plan to address.  I wonder with the spikes showing at the peak apex of the sinewave, are we dealing with a noise problem in the hardware.  With it being a prototype I am not at all concerned about your production soldering.  Of course, this means I will be removing the PCB from the case to address any bottom side issues as well.  If after rework I continue to see any problems, I may have a look at the BGA. 

On the upside, you have time to work on your software.  I want both of us to have full confidence in that hardware before getting back to the review.

joeqsmith:
Could you provide details on what all the self test entails?   

Thinking about my comment about it not being so much related to time but rather it being the positive apex of the signal, look at the last set of plots.  Note that the highest noise for all 4 channels is in that region.  Oddly we don't see that with the negative apex.  If you think the signal's shape is exacerbating the problem with this particular hardware, should we test it with say a squarewave?  Higher frequency?   

Basically, I am looking for your thought on proving out the hardware after rework.

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod