3 ms·

It’s wild they talk about the jitter in the pps signals but glossed over the jitter the oscilloscope?

marshray 1y ago
The scope should be capturing samples from the three channels synchronously. It appears to be set to trigger on the bottom trace (it appears still) and then retrospectively display the other two.
magicalhippo 1y ago
Given he's using the desktop PPS signal as a trigger reference, and compares the relative times, how would intrinsic scope jitter significantly affect that?
deleted 1y ago
[deleted]
guenthert 1y ago
Not sure about the Siglent oscilloscope used here, but my old LeCroy WaveAce 2032 (were Siglent had obviously it's hands on) has a trigger jitter of 0.4ns. I'd think the one used here will be of the same order of magnitude, i.e. negligible. Uh, the Siglent SDS 1204X-E used here has a "new, innovative digital trigger with low latency" ... But yes, as others have commented already, if only the relative jitter between the signals is of interest, the trigger jitter itself is inconsequential.
- magicalhippo 1y ago
  > Uh, the Siglent SDS 1204X-E used here has a "new, innovative digital trigger with low latency" ... Datasheet claims trigger jitter of <100 ps.
  - guenthert 1y ago
    Well, I looked for the data sheet and couldn't find it, just the ominous quote. Now, newly motivated, I did eventually find it (trick is to look for the data sheet of the series, not the model; SDS1204X-E being the 200MHz, 4 channel model of the SDS1000X-E series): https://www.batronix.com/files/Siglent/Oszilloskope/SDS1000X-E/SDS1004X-E_DataSheet_EN.pdf https://www.batronix.com/files/Siglent/Oszilloskope/SDS1000X...
    - magicalhippo 1y ago
      Ah, didn't recall they had two of em. I got the little brother so downloaded the datasheet back when I bought it. Always like to have those handy for any equipment I own.
wowczarek 1y ago
I would worry less about _trigger jitter_, especially for relative measurements, because unless it's one of those toy scopes, trigger jitter will be negligible for this purpose, so yes the scope, but less trigger jitter and more measurement jitter. For anything that involves a scope, I think it's good practice to specify how and what you are measuring - namely what termination, what trigger level and show what the pulse actually looks like on the scope. Where you are definitely right is that all those devices can produce completely different looking pulses, and only by looking at the pulse with a scope that has sufficient bandwidth you can pick the right trigger level that lands at a point of the waveforms that gets consistent characteristics, namely you stay away from the top of the pulse and tend to trigger somewhere mid-ramp that looks clean, and keep your paws away from those AUTO buttons! ...but this is all nitpicking as far as the post goes, this is where lots of electronics people get triggered (badum, tss!) where we have a network in the middle that is, essentially, chaos.

The scope should be capturing samples from the three channels synchronously. It appears to be set to trigger on the bottom trace (it appears still) and then retrospectively display the other two.

magicalhippo 1y ago

Given he's using the desktop PPS signal as a trigger reference, and compares the relative times, how would intrinsic scope jitter significantly affect that?

deleted 1y ago

[deleted]

guenthert 1y ago

Not sure about the Siglent oscilloscope used here, but my old LeCroy WaveAce 2032 (were Siglent had obviously it's hands on) has a trigger jitter of 0.4ns. I'd think the one used here will be of the same order of magnitude, i.e. negligible. Uh, the Siglent SDS 1204X-E used here has a "new, innovative digital trigger with low latency" ... But yes, as others have commented already, if only the relative jitter between the signals is of interest, the trigger jitter itself is inconsequential.

magicalhippo 1y ago
> Uh, the Siglent SDS 1204X-E used here has a "new, innovative digital trigger with low latency" ... Datasheet claims trigger jitter of <100 ps.
- guenthert 1y ago
  Well, I looked for the data sheet and couldn't find it, just the ominous quote. Now, newly motivated, I did eventually find it (trick is to look for the data sheet of the series, not the model; SDS1204X-E being the 200MHz, 4 channel model of the SDS1000X-E series): https://www.batronix.com/files/Siglent/Oszilloskope/SDS1000X-E/SDS1004X-E_DataSheet_EN.pdf https://www.batronix.com/files/Siglent/Oszilloskope/SDS1000X...
  - magicalhippo 1y ago
    Ah, didn't recall they had two of em. I got the little brother so downloaded the datasheet back when I bought it. Always like to have those handy for any equipment I own.

wowczarek 1y ago

I would worry less about _trigger jitter_, especially for relative measurements, because unless it's one of those toy scopes, trigger jitter will be negligible for this purpose, so yes the scope, but less trigger jitter and more measurement jitter. For anything that involves a scope, I think it's good practice to specify how and what you are measuring - namely what termination, what trigger level and show what the pulse actually looks like on the scope. Where you are definitely right is that all those devices can produce completely different looking pulses, and only by looking at the pulse with a scope that has sufficient bandwidth you can pick the right trigger level that lands at a point of the waveforms that gets consistent characteristics, namely you stay away from the top of the pulse and tend to trigger somewhere mid-ramp that looks clean, and keep your paws away from those AUTO buttons! ...but this is all nitpicking as far as the post goes, this is where lots of electronics people get triggered (badum, tss!) where we have a network in the middle that is, essentially, chaos.