pcm is the way to go. FM recievers will take any signal that is on their band and frequency. pcm is a digital square wave and if the signal does not fit, it will reject it. kind of like a change machine. it will accept only valid currency and anything else it will reject. it is very particular and wont give you any coins "unexpectedly" a change machine working like an fm receiver does would be like you stick a piece of paper, any kind, into it and it will give you something, but not necessarily coins. PCM is actually on the fm band but it is a square wave digital signal rather than an analog pulse.