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Rigol MSO5000 HiRes mode
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Mechatrommer:

--- Quote from: Fungus on October 30, 2022, 12:32:18 pm ---
--- Quote from: Mechatrommer on October 30, 2022, 12:05:20 pm ---if the noise bandwidth is way below this rate, say few KHz, then hope to destroy this noise in averaging (hi-res mode) is almost nill, ymmv.

--- End quote ---

If the noise is in the ADC then it's more likely to have extremely high bandwidth than be low frequency (in my unprofessional opinion).

In that case all the stuff we're seeing down low in the FFT would be aliasing of that VHF noise and hires mode would work perfectly.


--- End quote ---
aliasing is subjective (controversial) issue as its non-provable from DSO display (any noise/signal components greater than sample rate / 2) and since we believe they exist, so somehow they will affect measurement on the display. but then on FFT matter, from Anding post we can see reduction in magnitudes at higher frequency components (>300MHz?) means hi-res is effective at reducing those noise components, but then lower components (frequencies) noises are not affected and manifest themselves when larger time/div is selected (1us/div in Anding's earlier post), which lead to balnazzar's confusion, i believe. ymmv.
2N3055:
Some nice work here and kudos to Fungus for effort to sort out this question.
I don't have MSO5000 so cannot contribute in that way, but would like to point out this excellent document by Tektronix on the topic.

I deliberately didn't want to bring up any materials by LeCroy because they use different implementation (ERES) that is not what Rigol uses.
That would only bring confusion.

Tektronix Hires explanations explain well how it should work. Page 11.

Just a note: bits stated in document are theoretical. 8 bit scopes don't have ENOB (effective number of bits) of 8 bits but less. But improvements (12 bit is 4 bits more than 8 bits, so 4 bits of improvement) should be reasonably followed.
Also Tektronix says they use fixed point 16bit math in acquistion engine. We don't know anything about how Rigol did it. Claim by Rigol of max 12bits, means max 4 bits of improvement algorithm was implemented.



Fungus:

--- Quote from: Mechatrommer on October 30, 2022, 01:15:47 pm ---its non-provable from DSO display

--- End quote ---

Yep. Only Rigol engineers know for sure.

Conspiracy theory:

Maybe this is why the MSO5000 didn't have Hires mode when it was launched - they couldn't get it to work because of the noise spectrum  characteristics.

Maybe they only added it after a manager demanded it be put in the menu, and that this was the best they could do.
Fungus:
Conspiracy theory #2:

Even if conspiracy #1 is true, Hires mode still should work with certain combinations of sample rate and memory size, right...?

Maybe the filter the engineers came up with was carefully designed not to give visibly different results with different settings. People would notice that and complain.   :-X
skander36:

--- Quote from: Fungus on October 30, 2022, 01:39:50 pm ---... Hires mode still should work with certain combinations of sample rate and memory size, right...?


--- End quote ---

On Rigol 5k High Res effect is a little better visible on MSO's LCD display than on pics saved from screen. If you zoom in you can see better but not as clear as on other scopes.
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