RE: stuppid newb Q
AM is more prone to interference than FM.
PCM is Pulse Code Modulation, I guess the best way I am able describe it is digital encoding of the FM signal.
Each manufacturer has their own versions of PCM. JR for example has ZPCM and SPCM,I think the only difference is that SPCM has a servo resolution double that of ZPCM, making it very accurate.
PCM is different between all the makes (JR,Futaba,Hitec.....ect) that's why there are so many different acronyms for it.
Hope that helps