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Rigol DHO804 Test and Compare Thread

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Martin72:
I can't tell you how Rigol handles it.
I can test tomorrow whether the measured values are only taken from the screen.

Martin72:

--- Quote from: Randy222 on December 26, 2023, 06:53:28 pm ---On the DHO804, why does the scope lose signal sync if the vertical scale is increased?
Example;
Ch1 on the internal 1kHz 3v peak signal, set trigger to 1v, but then dial up the scale to 10v/div. The trigger does not change, so why the scope lose sync on the square wave (dancing signal)?

--- End quote ---

Have a look at the data sheet under "Trigger Sensivity".
It says 0.5div, at 10V/div and a 3V signal it is no wonder why it no longer triggers.

Martin72:

--- Quote --- The standard deviation of noise samples should not depend significantly on the memory depth (except when the number of samples is very small).
--- End quote ---

Here is another picture at 10ms/div, automemory (50Ohm).


I'll get back to it tomorrow and "drive through" everything.

Performa01:

--- Quote from: gf on December 26, 2023, 08:05:42 pm ---
--- Quote from: Martin72 on December 26, 2023, 07:46:53 pm ---As the memory depth increases, so does the noise, see pictures

--- End quote ---

Very strange. The standard deviation of noise samples should not depend significantly on the memory depth (except when the number of samples is very small).

Could this be related to the mapping of the samples to the screen?
Are the measurements taken directly from the captured samples or from the screen data?

--- End quote ---
The differences come from the very pronounced 1/f noise characteristic of scope frontends. Faster time base setting rises the lower bandwidth limit, thus cutting off a significant portion of the LF noise.

For example, a DSO with 1 GSa/s and 10 horizontal divisions (and automatic memory management) will have a record length of just 10 kpts and a lower bandwidth limit of 100 kHz at a time base setting of 1 µs/div.
The same DSO will have a record length of 10 Mpts and a lower bandwidth limit of 100 Hz at a timebase of 1 ms/div.


gf:

--- Quote from: Performa01 on December 26, 2023, 08:48:00 pm ---The differences come from the very pronounced 1/f noise characteristic of scope frontends.

--- End quote ---

Oh sh*t, I didn't expect it to be that much :phew:
Your explanation makes sense, of course.

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