Products > Test Equipment
Pocket-Sized 6 GHz 1 TS/s ET Scope
joeqsmith:
--- Quote from: SJL-Instruments on January 28, 2024, 06:26:54 pm ---There is a command that selects the internal clock source as the trigger (X1 sets internal source, X0 sets to normal trigger mode). For each acquisition, the software first tries in normal mode, and if no trigger is detected, issues the X1 command and retakes the CDF.
See attached image - we'll document this command in the next manual revision.
--- End quote ---
Please take the time to document ALL of the commands. Even if you have commands you feel are not something customers would/should use, they may still prove helpful.
*** Sending X1 or X2, it responds with OK Xn. Sending X1 followed with R, I do not get any data. There must be more to it.
--- Quote from: SJL-Instruments on January 28, 2024, 06:26:54 pm ---The software should automatically return to the internal trigger ("wait") mode if no triggers are detected (e.g. the signal source is removed). What happens when you try this - does the software freeze?
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The software displayed Wait but it stopped sweeping. I could apply a trigger signal and it remained in Wait. I can't tell you for sure that it froze. I have yet to perform a three finger solute to shake your software loose. I exited the software and restarted and it worked as normal. I can tell you that I am having a difficult time replicating it.
joeqsmith:
Using my software to collect all four channels with min/max active. I run the RF generator into a splitter then into each channel. Using 0dBm, 1GHz.
1) zoomed out showing 46 sweeps, 5ps resolution for 1ns. I make no attempt to align the channels and we can see that one channel is a bit off compared with the others like I had mentioned.
2) Looking at the minimum values of the peak area. Note how channel 1 is smooth where the others have some sort of pattern to them.
3) Looking at the maximum, we can see they are all smooth.
If I reset the collection and watch it, I can see when it will create a single mini-glitch. They are much smaller in amplitude than the original glitches. This appears very reproducible. Nothing special with the cables, splitter or RF gen. Have you seen these smaller spikes?
SJL-Instruments:
--- Quote from: joeqsmith on January 28, 2024, 07:41:55 pm ---Please take the time to document ALL of the commands. Even if you have commands you feel are not something customers would/should use, they may still prove helpful.
--- End quote ---
Got it - there are two remaining serial commands we'll document in the next revision: set CDF epsilon (section 2.2.1), and direct CDF measurement at V,t.
--- Quote from: joeqsmith on January 28, 2024, 07:41:55 pm ---*** Sending X1 or X2, it responds with OK Xn. Sending X1 followed with R, I do not get any data. There must be more to it.
--- End quote ---
We were able to get CDF data with the following procedure:
1. Plug in the scope.
2. Issue command X1.
3. Issue command R1 10000 10000 10000 10000 50000 50000 50000 50000.
Does this sequence fail to return data on your unit?
--- Quote from: joeqsmith on January 28, 2024, 07:41:55 pm ---The software displayed Wait but it stopped sweeping. I could apply a trigger signal and it remained in Wait. I can't tell you for sure that it froze. I have yet to perform a three finger solute to shake your software loose. I exited the software and restarted and it worked as normal. I can tell you that I am having a difficult time replicating it.
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The software is separated into a frontend and backend process. We can reproduce this behavior if we manually kill the backend process. We'll see if there's any code path that would crash the backend. (And also add code to restart it automatically, as a failsafe.)
In principle, this frontend/backend separation should also prevent the UI from freezing up, no matter what the scope does (i.e. the "three-finger salute" should never be needed).
SJL-Instruments:
--- Quote from: joeqsmith on January 28, 2024, 08:30:59 pm ---1) zoomed out showing 46 sweeps, 5ps resolution for 1ns. I make no attempt to align the channels and we can see that one channel is a bit off compared with the others like I had mentioned.
--- End quote ---
This is consistent with the specified max THD of the scope at 1 GHz - it's limited by Channel 1 at early times (11-12 ns). All other channels perform better than spec.
--- Quote from: joeqsmith on January 28, 2024, 08:30:59 pm ---2) Looking at the minimum values of the peak area. Note how channel 1 is smooth where the others have some sort of pattern to them.
3) Looking at the maximum, we can see they are all smooth.
If I reset the collection and watch it, I can see when it will create a single mini-glitch. They are much smaller in amplitude than the original glitches. This appears very reproducible. Nothing special with the cables, splitter or RF gen. Have you seen these smaller spikes?
--- End quote ---
These effects are from the input hysteresis interacting in a subtle way with the delay generator.
This is what limits the specified noise floor of the scope. The actual RMS noise in the smooth regions is about 5x better than specs (200 uV RMS).
Getting rid of it completely would likely require a different architecture and push the price up significantly.
joeqsmith:
As it continues to run, it's interesting that channel 1 never exhibits these downward spikes where the other three do. It never happens in the valley, only the peak. I would not have noticed it as I was only ever looking at channel 1 with my software until today. I'll take your word for it that it is the expected behavior from your design perspective. As a user, I would be concerned it was my signal generator causing this, then spending time hunting down a problem that isn't there.
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