If you remove the bridge from the output of the amp, you will see fig A on the oscope.
If you add a let say 5v dc supply in series with the output of the amp, you would see the same sinewave but shifted to the 5v mark. Fig B.
Now if you hook that 'shifted full sinewave' to the rotor, you would be able to observe a smaller sinewave running on a larger carrier sinewave (produced by the alternator.) at the stator when alternator is running.
Ths is very close to some waveforms on Andria`s patent.
Try verieng both carrier wave(alternator) and feed signal frequencies
HM