Really weird oscilloscope results when using Discovery Board with Python

[johannsi99]

Hi,

I am using the Discovery Board 2 and am testing its capabilities using the SDK (Python). I am measuring different waveforms at different frequencies. When measuring higher frequencies, I get really weird/wrong results. Starting at 10kHz but espescially in frequency ranges from 100kHz to 2MHz. Often there is no data recorded at all, sometimes the at the beginning or the end of the recording is zero with the rest being correct and sometimes the whole measurment is correct. On result is really puzzling as it shows a triangle, then a square wave and then nothing. During the whole recording, the input was a triangle wave generated by an extern signalgenerator at 200kHz.  One measurment before, i was measuring a rectangular wave. 
How can such a result be explained? 
Is there a problem with my code? I am using the same code as the AnalogIn_Record.py from the examples with only very small modifications for labels, axes, ... .

I really don't know how to solve this. I think there must be some error in the memory or communication with the board.
Would be really nice if someone could explain this to me, otherwise the oscilloscope is not usable for reliable measurments higher than 10kHz (with Python).

Thanks in advance and best regards,

Johannes

[attila]

Hi @johannsi99

The record streams data over USB which limits the sample rate to about 1-2MHz.
Use the default (single) acquisition mode to capture up to device buffer (8-16Ki) samples at up to maximum sample rate (100MHz).