Hi Guys,
This is my first oscilloscope so I'm not sure if this is expected behaviour or if there is something wrong with the scope.
In this example I am looking at two signals from an ESP32 development board.
When I have the lower signal probe disconnected at from the ESP32 board the top signal looks ok.
When I connect the lower signal probe to the ESP32 the signal seems to interfere with the top signal.
When I disconnect the lower signal probe from the oscilloscope but not from the ESP32 board I still see this interference.
Could someone please explain what might be going on here as I'm a bit confused!
All the best
Andy
Try just connecting the yellow signal by itself and work on improving the probe's ground connection until you get a cleaner signal without the overshoot spikes. (The shorter and more secure the ground connection between the probe and the DUT the better.)
Likewise, better probe grounding might help produce a cleaner waveform for the blue signal (i.e., minimize the spikes).
As for the blue signal showing interference even when the yellow probe is disconnected from the scope, if that is occurring when the yellow probe remains attached to the DUT, it would seem to indicate the yellow probe is picking up RF from something or otherwise contributing to the interference. (Presumably, the interference on the blue signal goes away when you disconnect the yellow probe not only from the scope but also from the DUT?)
It looks like these might be two separate issues, although perhaps if the probe ground connection is better made for the yellow signal (and maybe also for the blue signal) it might help reduce the interference impacting the blue signal. Fixing the yellow ground issue should be relatively easy, fixing the blue interference issue might take more work.