There seems to be a lot of disinformation about PCM. It is not mandatory to have the failsafe. It can be turned off like any other feature in the radio programming. With the failsafe off you can see glitches the same a non PCM. The advantage to PCM is the signal is much less prone to interference. The signal sent from the TX is encoded differently than non PCM. The rx is more selective and rejects more bad signals than a normal signal. PCM stands for pulse code modulation, FM stands for frequency modulation, AM stands for amplitude modulation. The PCM signal is more like a square wave than a non PCM signal and the rx can recognize this signal better while rejecting the enterference.