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Rigol DHO800 memory depth / bandwidth upgrades and noise level!
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Fungus:
I'm sure this question is going to be asked a million times over the next few years so I'll put this here as a reference.

My 'scope says "DHO804" on the front. I've modified the bandwidth and memory options.

Here's my new "About" screen:


Here's my new "Options" screen:


Here's my new memory depth with 4 channels enabled:


Here's my measured bandwidth:


nb. I'm using the bandwidth math from here and Martin72 confirmed the "100Mhz" bandwidth with a 200Mhz sine wave here.

(I don't have a SIGGEN that goes that high so I can only do rise times  :( )

All changes are harmless and 100% reversible. There are NO side effects.

Notice the difference in rise time and the shape of the yellow waveform between the last two images. That's because 321.5MSa/s isn't enough for a 197Mhz 'scope, ie. I'm seeing some aliasing.

(Solution: (a) Be aware, and (b) Turn off some channels when viewing fast signals and see if anything changes. If it does? Aliasing!)
Fungus:
I just removed my bandwidth upgrade (proof that it's reversible!):


Now my measured bandwidth is 128MHz:


I have no idea where Rigol get their "70Mhz" from... but don't complain!  :D
Warhawk:
Thanks, I lost interest in the other thread when it went off-topic with the gibbs' ears. I did not know that there is generally an option for extended memory. I found it now. I am happy for you and others. This was really annoying limitation.
ebastler:
I am wondering whether the 0.45 factor to convert risetime to bandwidth is a bit too aggressive here. Historically a factor of 0.35 has been used, which I understand is correct for simple 1- or 2-pole bandwidth limiting filters. The recent transition to 0.45 is justified when steeper, higher-order filters are used for bandwidth limiting.

But looking at the nice step response of the DHO800, without overshoot and ringing, I would assume that it uses a relatively "soft" lowpass filter. So maybe the classical factor of 0.35 is closer to the truth here? It would put the bandwidth closer to Rigol's specs.

Anybody here with access to a tunable sine wave generator which goes up to 200 MHz to measure the bandwidth in the frequency domain? And ideally an even higher bandwidth scope to check the generator output amplitude?  8)
Warhawk:

--- Quote from: ebastler on November 06, 2023, 03:27:59 pm ---Anybody here with access to a tunable sine wave generator which goes up to 200 MHz to measure the bandwidth in the frequency domain? And ideally an even higher bandwidth scope to check the generator output amplitude?  8)

--- End quote ---
I do have the access but don't have the scope  :-DD
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