Re: Phase modulation?
FM and PM are all the angle modulation in digital modulation,the relation is you can use the PHASE modulator to realize the FM modulation if you use an integrator to integrate the incoming source information,from the point of digital modulation,the phase modulation is the best,not the FM,for example,bpsk is more popular in DSS! this is a equalivent between the energe and bandwidth,and the difficulty of realization, for example, in GSM system ,it use the GMSK,its envelope is const ,or in otherwise,the PAR is almost one,so it is easy to desgin the power amplifier for GSM; but in CDMA system,if you use the BPSK,there are high requirement in the oscillator!
so if you want to know more about the FM and PM,i recommend you to read the reference book "analoge and digital commnuciation system" the author is the COUCH