Products > Test Equipment
Pocket-Sized 6 GHz 1 TS/s ET Scope
joeqsmith:
The following was taken from:
https://www.eevblog.com/forum/testgear/show-us-your-square-wave/msg5285605/#msg5285605
--- Quote from: SJL-Instruments on January 18, 2024, 01:54:52 pm ---
--- Quote from: hpw on January 18, 2024, 06:07:47 am ---
--- Quote from: joeqsmith on January 18, 2024, 03:40:43 am ---GigaWave with Tektronix S-52 tunnel diode head (<25ps Tr)
https://www.sjl-instruments.com/
--- End quote ---
Nice, what I would like to see the real time behavior, as 20..80% or 10..90% rise time changes over time :D
On a LeCroy easy to graph over time as rise f(t).
--- End quote ---
Thanks for the suggestion :) We'll add the ability to graph any measurement vs. time to the software. (Fastest update rate would be 1 datapoint per sweep.)
--- End quote ---
There's been some activity in that thread which reminded me about this request. It's been about 5 months since the original post, so I thought I would set this up and show it. I think I demonstrated this using my custom software back then.
Using your latest release, I can not figure out how. If it is a MATH function, the manual does not explain how to use it. Looking in the Extended Measurement Information, I don't see any options to graph the data.
A few other comments, bugs? If I select a custom scale, say 25mV/div. Then I save that waveform as a reference. When the new reference is displayed, us uses 20mV/div rather than the expected 25mV, requiring me to select Custom, then enter in the 25mV/div. I thought these two would always track but it appears not. Is there a reason why you made it work this way? Personally, I would rather it always work the same way and IMO, less keystrokes is always better.
If I select Color Grading for a waveform with vectors disabled, then save the waveform as a reference, the new waveform is shown with vectors disabled but the color grading is deselected. Is there a reason it does not match?
Have you ever considered adding a way to auto align the data? So, for example, we want to plot the risetime. Now, if the hardware drifts, the transition may move off the screen. For a long term trend, have you considered having the softeware adjust the position automatically (as a option) to keep the transition centered?
SJL-Instruments:
--- Quote ---Using your latest release, I can not figure out how. If it is a MATH function, the manual does not explain how to use it. Looking in the Extended Measurement Information, I don't see any options to graph the data.
--- End quote ---
Whoops, this slipped out of the pipeline at some point. We have a software branch with this feature but it was not merged. We'll release it by EOW.
For now you can export the entire sweep history from the Extended Measurement Information window, and plot it externally.
--- Quote ---A few other comments, bugs? If I select a custom scale, say 25mV/div. Then I save that waveform as a reference. When the new reference is displayed, us uses 20mV/div rather than the expected 25mV, requiring me to select Custom, then enter in the 25mV/div. I thought these two would always track but it appears not. Is there a reason why you made it work this way? Personally, I would rather it always work the same way and IMO, less keystrokes is always better.
--- End quote ---
This is a bug and will be fixed in next release (EOW).
--- Quote ---If I select Color Grading for a waveform with vectors disabled, then save the waveform as a reference, the new waveform is shown with vectors disabled but the color grading is deselected. Is there a reason it does not match?
--- End quote ---
We originally had the color-grading setting copied over, but during QA caught ourselves clicking the "Save as Reference" button multiple times because the software appeared unresponsive. What was happening is that the new overlaid waveform looked exactly identical to the original. The current behavior ensures that the new trace is a different color.
--- Quote ---Have you ever considered adding a way to auto align the data? So, for example, we want to plot the risetime. Now, if the hardware drifts, the transition may move off the screen. For a long term trend, have you considered having the softeware adjust the position automatically (as a option) to keep the transition centered?
--- End quote ---
We can probably have this in by EOW. The UI requires some thought - given how the hardware works, only one transition can be followed at a time. We would allow the user to select one channel to track, and adjust the timebase at the end of each sweep.
joeqsmith:
The reason I brought up the tracking is when looking at these fast transitions, I know that vintage Tektronix pulser will drift a fair amount. Because the pulser's cycle time is so slow, sweep times can easily be several minutes. Using the setting I selected back when I posted the risetime, it requires about 3 minutes to collect a single sweep.
I assume the original question was looking for more than a couple of sweeps, and running a long term test (guessing maybe a day or so) is currently not possible with what I have on-hand without the aid of some sort of auto tracking. That or I need to try and maybe temperature stabilize it.
***
Showing two sweeps after an 8hr warmup. Drifts about 25ps (added delay).
joeqsmith:
It may be nice to be able to adjust (drag) the reference independent from the other channels. For example, if I collect data from channel 2, then change the setup to collect on channel 3 as shown. I want to manually align the two edges.
Also, just an FYI, the setup is a bit different than when I first took that data but we are still well in the ballpark of the original 35.8ps measured. Also, all below your published typical 40ps, which is good to see!
SJL-Instruments:
--- Quote from: joeqsmith on June 09, 2024, 04:14:10 pm ---It may be nice to be able to adjust (drag) the reference independent from the other channels. For example, if I collect data from channel 2, then change the setup to collect on channel 3 as shown. I want to manually align the two edges.
--- End quote ---
On a reference waveform, you can open the channel settings and enter a timebase shift to adjust the horizontal position.
On a "physical" channel, this setting only relabels the timebase (due to hardware limitations). The behavior for a reference waveform differs in order to allow exactly the application you're describing.
--- Quote from: joeqsmith on June 09, 2024, 03:46:42 pm ---The reason I brought up the tracking is when looking at these fast transitions, I know that vintage Tektronix pulser will drift a fair amount. Because the pulser's cycle time is so slow, sweep times can easily be several minutes. Using the setting I selected back when I posted the risetime, it requires about 3 minutes to collect a single sweep.
I assume the original question was looking for more than a couple of sweeps, and running a long term test (guessing maybe a day or so) is currently not possible with what I have on-hand without the aid of some sort of auto tracking. That or I need to try and maybe temperature stabilize it.
***
Showing two sweeps after an 8hr warmup. Drifts about 25ps (added delay).
--- End quote ---
Thanks for clarifying. For a single rising/falling edge this is not too hard. For arbitrary waveforms it should still be possible using autocorrelations, but we'll see if this works in practice.
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