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florentbr / OWON-VDS1022

Unofficial release for the OWON VDS1022/I Oscilloscope
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Bode Plot #57

Closed LeonIndman closed 2 years ago

LeonIndman commented 2 years ago

Hi! Is it possible to implement Bode Plot for this device?

florentbr commented 2 years ago

To plot the frequency response, the software would need to sweep the frequencies. How is it supposed to do it since this device doesn't have a signal generator?

LeonIndman commented 2 years ago

An external generator with 2 channels can be used. This is not difficult. The VDS1022 has an external clock input. For example, the popular DSO5102P oscilloscope also does not have a built-in oscillator, but it does have a Bode Plot capability. https://www.youtube.com/watch?v=KPuj072zMvw

florentbr commented 2 years ago

The VDS1022 has the same fake Bode Plot capabilities as the one from your link. It's called roll mode or slow mode. I wouldn't call it a Bode plot given that it doesn't have a log scale. It's also limited to the current time-range and buffer size. I'm not sure where you are going with this.

LeonIndman commented 2 years ago

Thanks, you are probably right.

florentbr commented 2 years ago

I made an error in my last comment, it's not slow/roll mode but low sweep mode. Here's one interesting video from EEVBlog on the subject: https://www.youtube.com/watch?v=uMH2hGvqhlE

LeonIndman commented 2 years ago

Does the DSO5102 have a similar BodePlot mode?

  1. The frequency of the two channels must be the same.
  2. According to the decibel and phase difference and frequency, users can draw the amplitude frequency diagram, phase frequency diagram and the amplitude phase diagram. Bode 1
florentbr commented 2 years ago

Does the DSO5102 have a similar BodePlot mode?

I don't have one, but from your capture it just gives the Phase angle and the Gain for a single frequency.

florentbr commented 2 years ago

I'm closing this request since it's too broad.

The application doesn't give the gain or phase shift but it can be easily measured with the cursors.

If your goal is to tune a cut-off frequency, then sweep the frequencies over 1 second with a sine generator or with a sound card. To visualize, setup the VDS1022 with a 50ms timebase, normal trigger and peak sampling.

If it's to plot a Bode graph, then open a Jupyter notebook and record/plot the gain and phase in a loop while manually sweeping the frequencies.