Ok, first of all let's get the terminology straight. PCM radios are also FM radios. Confusing huh?? Yes. Our radios either AM or FM to broadcast their signals. Most radios these day are all FM radios. So what is PCM. This is the way the signal is encoded for broadcast. There are two major types of modulation and those are PPM and PCM. The easiest way that I could describe PPM and PCM would be to consider them languages, such as French and English. Both types of languages can be broadcast over a radio, but the person on the other end has to be able to understand the language being spoken in order to get the message being spoken. Same prinical here. PPM and PCM are the languages that are spoken by the transmitter, and you need a receiver that can understand those languages. The most common moduation is PPM, which most radios have. Higher dollar radios have PCM in them.

Ken