Products > Test Equipment
Rigol HDO1000 and HDO4000 12bit oscilloscopes launched in China
Fungus:
--- Quote from: rf-loop on January 30, 2023, 03:48:17 pm ---It is not my problem if you do not understand anything about these things.
--- End quote ---
The first thought that came into my head when I saw those screenshots wasn't that the sky was falling.
My first thought was "spectral leakage", followed by "I wonder what window function they're using?"
If those questions didn't enter your head before you made a million anti-Rigol posts then... :-//
I'll leave it to the people who own them to figure out what's going on.
Me? I suspect the FFT math is correct (it's not exactly rocket science) but the sampling rate and buffer size is completely unreasonable, ie. It's an edge case.
Is it a problem? That depends on how easy it is to get into that edge-situation with this 'scope.
2N3055:
--- Quote from: Fungus on January 30, 2023, 03:57:36 pm ---
--- Quote from: rf-loop on January 30, 2023, 03:48:17 pm ---It is not my problem if you do not understand anything about these things.
--- End quote ---
The first thought that came into my head wasn't that the sky was falling.
The first thought was "spectral leakage", followed by "I wonder what window function they're using?"
If those questions didn't enter your head before you made a million anti-Rigol posts then... :-//
--- End quote ---
Seriously, if you don't understand, don't enter the discussion...
Spectral leakage has nothing to do with the fact that sampling rates and sampled data and analysed graph are not correlating...
It's all right to not know something..
But you're not helping HDO1000 users by pretending there is no problem.
And even if we presume basic math behind this FFT is correct, how do you use this thing? Several basic parameters are not available and you have no control over process.
So FFT at this stage needs more work. Which is a shocker... Whole scope is basically in alpha stage. Documenting all the problems and reporting them to Rigol is only way for users of HDO ever getting a scope that actually works well...
So if you want to help, go buy HDO1000, and we'll work together to debug it, time permits...
Putting head in a sand is no help to ACTUAL HDO users. Fixing bugs is...
And if we were Siglent shils (people involved into this FFT troubleshooting), we would sit back, laugh and enjoy this clusterfuck and NOT help Rigol fix stuff they don't know by themselves...
Robert is a nice guy, and I would like to help. You should find somebody to help too. It feels nice, it's a worthy cause..
dreamcat4:
ok so in simple layman's terms, for these observed results:
which of the following *could be true i.e. we cannot be sure yet, maybe we can at least rule out some of these possible reasons?
* there is an issue with the analog linearity, i.e. adc or in hardware. that is not fixable
* there is a firmware bug, or other issue with the firmware that is either (as mentioned) possible windowing FFT, or misleading, not documented, not clear in the UI
* there was a problem taking measurements or in testing methodology, the assumptions or interpretation of what they mean given the setup + settings input into the machine
so for example you might answer 1+2, but not 3
or 1,2, or 3
Sorry this probably is not a very helpful quesitron. A better line of enquiry would be to consider what next different tests could be done, and/or with other sorts of test equipment.
Just as a novice I am asking to try better to understand the implications here. For example if it could be a firmware bug, then I guess it would make sense that Rigol should need to be asked / should answer if they will address in firmware. Things like this. If that isn't an overstep to be suggesting like that...
Fungus:
--- Quote from: 2N3055 on January 30, 2023, 04:12:57 pm ---It's all right to not know something..
--- End quote ---
FFT mirroring is a thing. Here's a Teletubbies video:
(skip to 5:33...)
--- Quote from: 2N3055 on January 30, 2023, 04:12:57 pm ---But you're not helping HDO1000 users by pretending there is no problem.
--- End quote ---
I'm not pretending there's no problem, just that we need to know every last setting ... and the same settings tried on other devices.
--- Quote from: 2N3055 on January 30, 2023, 04:12:57 pm ---And even if we presume basic math behind this FFT is correct, how do you use this thing?
--- End quote ---
You make sure that Nyquist is high enough for the signal you're looking at.
(Which you're supposed to do anyway)
Fungus:
Question: What happens if the input signal is 99.5kHz?
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