Re: Why is Phase modulation (PM) not so popular in broadcast
I guess it might be a reason AM and FM demodulation were (are) easier to handle: AM can easily demodulated with an envelope detector, FM with the help of a PLL
main reason is as arefeidi says, the reciving hardware becomes more complex for handling and detection of PM.
but the smart think about PM, is that you can transmit serveral logical bits at the same time.