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Siglent SDS800X HD Review & Demonstration Thread

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gf:

--- Quote from: markone on May 11, 2024, 02:57:49 pm ---If the problem is not strictly harmonics related it could be that FW guys did some work on FFT math ... I want IT !

--- End quote ---

That's why I'd like to look at the raw samples, and why I asked for a .bin file with 100M points. And yes, I ask for 2 GSa/s first because I want to preserve as much information as possible from the original signal. I can downsample myself.

markone:

--- Quote from: ebastler on May 11, 2024, 03:13:03 pm ---
--- Quote from: markone on May 11, 2024, 03:07:23 pm ---What have you changed from your previous spectrum image ?

--- End quote ---

Adjusted the signal generator frequency such that the scope "sees" an exact 50 MHz. I wanted to get the point across that we are seeing harmonics beyond the Nyquist limit, folded back in the spectral range, if the input frequency is slightly off. Doesn't look like a bug to me.

--- End quote ---

Just replicated on my DSO, I had to shift down the generator frequency to 49.999350MHz to obtain a perfect 50MHz reading, normally I get 50.000650.


--- Quote from: ebastler on May 11, 2024, 03:13:03 pm ---My guess would be that 2N3055 sees less of them since he is using a better signal generator.

--- End quote ---

My guess too, reason why I asked him levels of 2nd and 3rd harmonics, anyway I would be glad to try the new incoming FW  :)

In this case the folded back harmonic/s would Zero beat with central carrier producing a clean near spectrum image.

markone:

--- Quote from: gf on May 11, 2024, 03:25:00 pm ---
--- Quote from: markone on May 11, 2024, 02:57:49 pm ---If the problem is not strictly harmonics related it could be that FW guys did some work on FFT math ... I want IT !

--- End quote ---

That's why I'd like to look at the raw samples, and why I asked for a .bin file with 100M points. And yes, I ask for 2 GSa/s first because I want to preserve as much information as possible from the original signal. I can downsample myself.

--- End quote ---

I would be glad to provide it but I have no time now to write an application program, do you guys know if exist something usable for the purpose ?

EDIT : foldback should be feasable with decimated vector that supplies FFT Math, not with original data sampled @ 2GSa/s, right ?

gf:

--- Quote from: markone on May 11, 2024, 03:28:00 pm ---
--- Quote from: gf on May 11, 2024, 03:25:00 pm ---
--- Quote from: markone on May 11, 2024, 02:57:49 pm ---If the problem is not strictly harmonics related it could be that FW guys did some work on FFT math ... I want IT !

--- End quote ---

That's why I'd like to look at the raw samples, and why I asked for a .bin file with 100M points. And yes, I ask for 2 GSa/s first because I want to preserve as much information as possible from the original signal. I can downsample myself.

--- End quote ---

I would be glad to provide it but I have no time now to write an application program, do you guys know if exist something usable for the purpose ?

--- End quote ---

User manual:


--- Quote ---29 Save/Recall

The SDS800X HD supports saving setups, reference waveforms, screenshots, and waveform data
files to internal storage, external USB storage devices (e.g. U disk), or SMB File Share. Saved setups
and reference waveforms can be recalled as needed.
For details of SMB File Share, refer to the section “SMB File Share”
...

--- End quote ---

Save the trace as Binary Data (.bin file).


--- Quote ---EDIT:  foldback should be feasable for decimated data vector, not for original data sampled @ 2GSa/s, right ?

--- End quote ---

Already sampling the analog signal folds the spectrum.
And down-sampling folds it again to an even smaller frequency range.

Folding back is not possible in general, since the folding is a N:1 mapping in the frequency domain.

markone:

--- Quote from: gf on May 11, 2024, 03:40:32 pm ---
-snip
Already sampling the analog signal folds the spectrum.
And down-sampling folds it again to an even smaller frequency range.

Folding back is not possible in general, since the folding is a N:1 mapping in the frequency domain.

--- End quote ---

I mean in respect to "real" sampleable harmonics that should be 2nd, 3rd and 4th, all below Nyquest @ 2GSa/s.

Anyway :

1) link to compressed bin file 100MSa @ 2GSa/s (size is about 95MB) : https://file.io/su83ZcbhPr4d
2) link to compressed bin file 40MSa @ 2GSa/s (size is about 40MB) : https://file.io/hxDe9PqKBLGY


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