Phase modulation?

Can me some people explain relation between FM and PhaseM. I meen, why it's FM better than PM?


thanks!

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

To put it simply: In FM the freq deviation is dependant on the mod freq only. In PM the freq deviation is dependant on the mod freq and its amplitude

Analog phase modulation, i think you need a coherent receiver while FM does not. IN digital mod, most of them are phase modulation (PSK, QPSK, DQPSK, QAM etc)

in fact ,if you use the diffierence code method,for example the DPSK,no need coherent demodulation,this is used in the wireless lan,such as STEL-2000chip use this method to demodulate the DPSK signal

FM is better than PM for practical implementtion issues

FM Better? For what application. Find me a satellite that uses FM downlink! They all use qpsk, since you only need 1/2 the transmit power for a given data rate. You gotta love that coherent detection.

In PM the phase of the carrier changes with amplitude of the message signal

while in FM the frequency of the carrier chages

THX

40G 100G most use QPSK ,phase modulation is good technology...