Products > Test Equipment
Sub: Rigol's DHO800 Oscilloscope (Gibbs Effect & Aliasing Misunderstanding)
Fungus:
--- Quote from: Mechatrommer on October 28, 2023, 08:52:19 pm ---argument 1) DHO900 is not properly designed because at its rated BW (230MHz) can alias when all channels turned on (312.5MSps)
my answer:
1) its true, but why need to push DHO900 to see at its rated BW when you want 4 channels? you know its only 312.5MSps, lets just do < 125MHz circuit.
--- End quote ---
I agree that you shouldn't push it but limiting the circuit isn't practical when you have pulses.
The practical solution is to monitor the preshoot and turn off some channels when you have a lot of it and you need a better view of the circuit.
Mechatrommer:
--- Quote from: Fungus on October 28, 2023, 09:23:54 pm ---The practical solution is to monitor the preshoot and turn off some channels when you have a lot of it and you need a better view of the circuit.
--- End quote ---
if i got preshoot, i'll turn off Sinc, if there is significant difference, i know its artifact, but if not, then i can guess the signal is real, or either undersampled, here we need to think carefully and if needed rig up experimental setup or simply, go find 10GSps scope. and turning off channels in case of suspicious is what exactly we do.. make sure there's written 1GSps too on screen. the keyword is, Know Thy Tools... :-+
--- Quote from: tautech on October 28, 2023, 09:17:48 pm ---Let me again present 2 GHz DSO 10GSa/s in DOT mode.
[img]
BW and sampling rates are everything.
--- End quote ---
good! thats "more accurate" ;D :-+ but thats not apple to apple anymore with DHO800/900... cheers.
Fungus:
--- Quote from: Mechatrommer on October 28, 2023, 09:32:28 pm ---good! thats "more accurate"
--- End quote ---
This still needs explaining though:
Mechatrommer:
--- Quote from: Fungus on October 28, 2023, 09:58:08 pm ---
--- Quote from: Mechatrommer on October 28, 2023, 09:32:28 pm ---good! thats "more accurate"
--- End quote ---
This still needs explaining though:
[img]
--- End quote ---
thats where turning Sinc off, or plot in dot mode, and dial down to proper timescale can give extra clue as to why. circuit debug is not simply looking at one screenshot and be happy. if ringing is same freq or more as sampled dots, thats probably interpolation artifact. but if one cycle of ringing sampled by 10 points or more and you see almost straight lines between dots then that probably real.
Fungus:
--- Quote from: Mechatrommer on October 28, 2023, 10:00:58 pm ---
--- Quote from: Fungus on October 28, 2023, 09:58:08 pm ---
--- Quote from: Mechatrommer on October 28, 2023, 09:32:28 pm ---good! thats "more accurate"
--- End quote ---
This still needs explaining though:
[img]
--- End quote ---
thats where turning Sinc off, or plot in dot mode
--- End quote ---
That is in dot mode...
(according to tautech)
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