Some possible issue with a scope acquiring simultaneousl with two channels
1 input signal, sine wave ~ +/- 2.5V , period ~ 8 microsec
Measurement on PicoScope 6:
Both Ch A and B on same +/- 5V input range, trigger is on channel A, level 0V. All good
The signal feeds into both channels, using a BNC splitter.
Same setup but time windows reduced to 500ns: OK
Now I lower ch B input range (the one with no trigger on it) to 500mV : The 0 crossing in theory identical starts being offset. The changing slope on signal B is to be expected since the vertical range (and scaling) has changed accordingly.
Now I lower ch B input range to 50mV : The 0V crossing is now ~50ns offset
Why is there an offset ? is this to be expected?
If I swap the cabling going into the input channels A and B no change, the delay does not follow the channel swap so it rules out a delay in the external cabling.
Also the delay always appears to be such B rises occurs before A rises, whichever channel is set as trigger.