Thanks @jpthibault.
With all other potential issues out of the way, I finally solved it:
It was indeed a ghost peak problem. With my limited experience in power analysis, I wasn’t aware of the magnitude of ghost peaks. What I formerly though was the AES algorithm and lead to significant spikes in the plot turned out to be something completely different. The actual AES spikes where hiding somewhere in the noise (the actual peak is at sample 1900 rather than 1250 or 4300).
With the full_diffs_list plot in the Ghost Peaks chapter
fig = cw.plot()
for subkey in range(0, 16):
fig *= cw.plot(full_diffs_list[subkey][known_key[subkey]])
fig
I finally received the following result:
zooming in on the now colorful peaks:
Setting the following parameters before sampling helped me to window the correct range:
scope.adc.offset = 1800
scope.adc.samples = 900
Big thanks to the NewAE team for the great support and patience.