I have been observing pulsed RF signals which are fed to a negative polarity diode detector whose output is hooked up to the scope input. Until now, as expected the output of the detector is always a negative voltage envelope. Now I am seeing the scope display show positive spikes. Is it possible that this is a result of the 12 bit ADC output wrapping around from minimum (negative) value to positive value ? I have observed in other situations where I set the vertical sensitivity too small and the input signal exceeds the maximum displayable it shows a red '!' overflow indication.
Is it possible that in my latest observations the value has wrapped around so the scope (or the Picoscope software, whichever does overflow detection) does not know that there is an overflow ? The other possibility is that the diode detector is breaking down but that is unlikely given the small amplitude of the input signal.
Thanks for any info,