TKG, thanks for chiming in. You confirmed what I have said in the past.
Also, PPM and PCM are the same except for the modulation of the RF signal and the checking data that is transmitted in PCM mode that is not transmitted in PPM mode. PCM is better able to ignore the noise. It will still effect the receiver's ablilty to receive a signal.

Don't think that a PCM receiver will improve your reception in a high RF noise situation.