Products > Test Equipment
Pocket-Sized 6 GHz 1 TS/s ET Scope
SJL-Instruments:
--- Quote from: joeqsmith on February 28, 2024, 01:59:16 am ---I appreciate trying to sell it into the hobbyist market... I can't afford new prices and my only choice is used.
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We've decided to offer a 35% hobbyist discount. That puts the 6200 model at under $1500. One of our hopes when launching the product was to give students/hobbyists access to 6+ GHz bandwidth who otherwise can't afford it. Sacrificing some margin to better achieve this goal is worth it to us.
If you're a hobbyist designing your own PCBs, it might not be as big of an issue to include SMA breakouts and/or a pretrigger. This compensates for the lack of probes (for now) and sequential sampling. This of course depends on the application. But being able to see things on the timescale of picoseconds is a qualitatively new capability.
joeqsmith:
--- Quote ---It's important for customers to feel confident that support will continue. We have baked the software development cost into the price of the product, and suspect that the earlier attempts did not.
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I would hope anyone who has followed along would come to this conclusion.
Trying out the new software now. Shown with PAM16 30SPCDF and 10k min/max, followed by PAM16 with 100SPCDF. Most of the error is my home made really poor setup I built for this test. Too embarrassing to show that level of craftsmanship. :-DD No doubt a real RF generator would do a much better job. Next I changed to PAM8 with 100SPCDF, much better. Then finally set the min/max to 20k. Wow! Sure it's slow, but still, very impressive.
joeqsmith:
That's one nice price break!
--- Quote from: SJL-Instruments on February 28, 2024, 04:32:57 am ---If you're a hobbyist designing your own PCBs, it might not be as big of an issue to include SMA breakouts and/or a pretrigger. This compensates for the lack of probes (for now) and sequential sampling. This of course depends on the application. But being able to see things on the timescale of picoseconds is a qualitatively new capability.
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For anything digital this may very well be the case.
Shown with 20k min/max, 100SPCDF. What is interesting about this plot is the areas where we see the speckles. Of course, turn up the brightness, it is loaded with them. Even with the min/max set to 30k. PAM4 is certainly doable. It will be interesting to see how the new firmware compares, but this is a huge step in the right direction! Thanks.
joeqsmith:
Going back to PAM4, single gate test (uneven distribution). Note that the gaps are no longer present. Any idea what causes there to be a harsh lines when looking at the speckles? Note at the start of the first transition, they are fairly sparse. Then as we work our way to the next transition, they don't has the same density. As the scope continues to sweep this pattern repeats.
SJL-Instruments:
--- Quote from: joeqsmith on February 28, 2024, 05:26:43 am ---Going back to PAM4, single gate test (uneven distribution). Note that the gaps are no longer present. Any idea what causes there to be a harsh lines when looking at the speckles? Note at the start of the first transition, they are fairly sparse. Then as we work our way to the next transition, they don't has the same density. As the scope continues to sweep this pattern repeats.
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This is a subtle point.
The root cause is the fact that we change the query voltage for all channels in parallel when acquiring CDF data. If the query voltage for Channels 1, 3, 4 (hidden) were fixed during CH2 acquisition, the speckles would not appear. A hacky way to do this is to set CH1,3,4 to 5 mV/div and CH3,4 offset to -10V to force the comparator outputs to a constant at each post-trigger delay, by always clipping the waveform.
There's a small (~100 uV) digital-to-analog crosstalk from the comparator output of CH1,3,4 to the analog input of CH2. Since the PDF is computed using CDF differences, this doesn't matter if the comparator outputs of CH1,3,4 are constant. But if they're not, then the input of CH2 is bumped up or down by ~100 uV depending on what the other channels are doing. This is enough to perturb the CDF up or down by a fraction of a percent, in a way that does not cancel upon subtraction.
Of course, when multiple channels are visible, the only way to avoid this is to issue one R command per visible channel, each keeping all but one query voltage constant. This would slow down acquisition if multiple channels are visible. We could add this mode in software, and it would allow acquisition of very clean eye diagrams. But you're now probing the limits of the hardware.
To be clear, if you change the CH1 clock duty cycle, the speckled regions will change accordingly. If CH1,3,4, are always clipped (either high or low), the speckles should largely go away.
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