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Rigol MSO5000 HiRes mode

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Mechatrommer:

--- Quote from: 2N3055 on October 30, 2022, 06:59:40 pm ---Hires usually also yields less data points on output than input, I.E. it downcoverts to resulting lower sample rate by filtering. Note that it doesn't have to downconvert (it could just lose some data at end and begging) but it is not usually implemented that way. It is usually acquisition mode that means you don't have original data. That might have a meaning to user or not, depending of what they are doing with it.

--- End quote ---
out of curiosity, i checked hi-res mode of my ds1054z (i dont usually use this mode), set display type to dots, sin(x)/x off... at smallest 5ns/div, i can still see dots are in accordance to 1GSa/s, no BW reduction when i check with one of my fastest pulser (Sync output of UTG962 AWG) reading about ~4ns risetime. textbook averaging should show some BW degradation and reduced sample points. on larger time/div (µs-ms/div), hi-res does improve displayed noise on all range setting. so i'm guessing there is trade-secret trick going on in FW (if not in FPGA) that doing hi-res at different sample rate depending on the selected time/div. and it maybe disabled when smallest time/div is selected. i guess what Anding posted earlier looks like MSO5000 is doing "strictly from textbook" boxcar or running average... ymmv.

gf:

--- Quote from: Mechatrommer on October 30, 2022, 09:21:12 pm ---i guess what Anding posted earlier looks like MSO5000 is doing "strictly from textbook" boxcar or running average... ymmv.

--- End quote ---

This was my first guess as well, but here's evidence that the filter is a different one:
https://www.eevblog.com/forum/testgear/rigol-mso5000-hires-mode/msg4492600/#msg4492600

If it were a boxcar moving average, then the main and side lobes of the corresponding sinc frequency response would be clearly visible in the hires spectrum. But there are no lobes at all in the spectrum.

[ Exponential moving average (IIR) might be a suitable candidate as it has a roughly similar frequency response shape with a fairly flat stop-band and only modest stop-band rejection - but that's just speculation. ]

Martin72:

--- Quote from: Rigol Manual ---Note:
 The "Average" and "High Res" modes use different averaging methods. The
former uses "Multi-sample Average" and the latter uses "Single-sample
Average".
 In "High Res" mode, the oscilloscope improves the measurement accuracy at
the cost of bandwidth. Each time the sampling rate changes, a window
displaying the current bandwidth appears at the lower-left corner of the screen.
 In "High Res" mode, the highest waveform refresh rate mode is not supported.
--- End quote ---

At all "hi res" pics posted here, I can´t discover such a window...

Anding:
It flashes up in a notification window, usually “-3db at 100MHz”, but is on screen only a second or two

Martin72:

--- Quote --- usually “-3db at 100MHz”,
--- End quote ---

No other values ?

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