tek00000.png shows the fastm signal (yellow) and pcm signal (cyan) as given from the TTFSS field box.
It was noticed that the pcm signal never crossed zero and always had a slightly saw tooth appearance
to it. The same two signals taken from the TTFSS board (TP10 and TP9 respectively) are shown in
scope_11.png. Clearly the pcm signal from the field box is broken. Either the differential amplifier
(N14) or the differential-to-single ended amplifier (N15) is faulty.
More to follow.
Rick / Peter
The PCM signal from the field box and recorded by the DAQ is an rms value. So, it will never be negative.