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Rigol HDO1000 and HDO4000 12bit oscilloscopes launched in China

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tv84:

--- Quote from: 2N3055 on January 30, 2023, 09:30:04 pm ---But if people keep buying it like crazy despite bugs, because it's cheap, they have very little incentive to fix things..

--- End quote ---

True words.

I think this forum is a niche... Most people only look at the wallet.  :-// 

But, I'm still betting on Rigol to fix all this stuff. Looking at the odds, I'm might win a load of $$$.   :D

Njk:

--- Quote from: tv84 on January 30, 2023, 05:17:19 pm ---Shouldn't the FFT stop at 100kHz if you have the 200kSa/s ? That would solve the picture at 200 kSa/s and save Rigol's honor.  :)

But then, why does the 400kSa/s show the same mirroring?  :palm: 

These are the moments where you need an engineer next to the GUI programmers or in the betatesters group...

I wonder how such a bug passed the FFT QC tests?!?  :-//

--- End quote ---

It seems Rigol uses some code that is shared. So the bugs are shared as well. Early I've noticed the same inconsistent Sa/s values for FFT sampling rate vs. scope's sampling rate in the 1054Z model. No wonder the HDO series are also affected.

https://www.eevblog.com/forum/testgear/rigol-ds1000z-series-buglist-continued-(from-fw-00-04-04-03-02)/msg4536227/#msg4536227

Martin72:

--- Quote ---It's easy to sit here saying they ought not to have released it and that they should be fixing it, but... we have no idea what's going on over there.
--- End quote ---

At least they could build the scopes and ship them to the world, despite lockdown.

Martin72:

--- Quote from: tv84 on January 30, 2023, 10:16:00 pm ---I think this forum is a niche...

--- End quote ---

You underestimate this forum my friend...

gf:

--- Quote from: switchabl on January 30, 2023, 09:48:13 pm ---I am not sure that the part to the right of fs/2 is actually a perfect mirror image. If you look at the second screenshot in https://www.eevblog.com/forum/testgear/rigol-hdo1000-and-hdo4000-12bit-oscilloscopes-launched-in-china/msg4668886/#msg4668886 the image seems to be a few dB down. Also in this case sampling rate is 200 kSa/s (acquistion) -> 256.41 kSa/S (FFT). That suggests an interpolation/resampling filter. In the next screenshot there is downsampling 2 GSa/s -> 25.64 MSa/s, which actually makes some sense to improve resolution at low frequencies.

Unlike the 2x upsampling case, that actually has potential for introducing less-obvious images < fs / 2. So here's hoping they got that right.

--- End quote ---

You are right, if the FFT sample rate is not 200kSa/s, but 256.41 kSa/s, then at least this image can't be a mirror.
Actually only the 3rd image with 2 GSa/s -> 25.64 MSa/s decimation looks OK.
The 4th image with 500 MSa/s -> 5.26 MSa/s decimation has too many spurs, IMO.
Decimation can make sense to improve resolution, by why such weird sample rates like 25.64 MSa/s (decimation by factor ~78 which is neither decimal nor power of two)?

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