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Why not phase modulation ?

  1. Apr 20, 2005 #1
    I want to know why phase modulation (PM) transmitters are not used for practical broadcasting, though its almost similar partner frequency modulation (FM) is used widely for broadcasting.
  2. jcsd
  3. Apr 20, 2005 #2


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    PM has been used in two-way radios for many years. Probably not anymore, but at one time was common.
  4. Apr 21, 2005 #3

    pm is more suited to transmit discreet phase states usually for digital data. Probably the most widely used modulation is QAM (quadriture amplitude modulation) which combines amplitude and phase shift keying to trasmit large amonts of data very quickly. The most common application is the cable modem, satellite tv, and digital cable tv.
  5. Apr 26, 2005 #4
    Response to Phase Modulation by Jha,Shambhu Nath



    I am Telecom Engineer at Nepal Telecom,Nepal.
    Response to above query:

    The phase modulation necessitates complex receiver due to phase ambiguity in comparision to frequency modulation.So it is not prefered for transmmiting broadcasting.

    Jha,Shambhu Nath
  6. Apr 28, 2005 #5
    It should be, Mr. Shambhu

    Thank you Mr. Shambhu,
    I think it should be the reason. What I think is that if modulating signal amplitude is increased beyond certain amplitude, phase will exceed pi or 2*pi and it will be difficult to distinguish it. Thus high level modulation will be somewhat difficult.
    Moreover I think multipath propagation will bring a lot of phase related problems.

    saikat m
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