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    Diff bet FM and PM

    what is the diff bet FM and PM?
    i read from a book that freq diff of FM depends on freq of modulating signal but phase dev of PM is indep of freq of modulating signal.
    pl give the respective formulas for freq & phase dev also.

    •   Alt27th August 2004, 15:40

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    Re: Diff bet FM and PM

    In FM, the information of a signal is encoded in its frequency. Similarly for PM, the information is encoded in its phase. Both modulation schemes use a carrier frequency as a reference.

    A FM modulated signal with message signal x(t) has the form
    A sin(2*pi*(fc+delta(f))*t) where delta(f) is the frequency deviation and is a function of x(t).

    A PM modulated signal with message signal x(t) has the form
    A sin(2*pi*fc*t + p) where p is the phase and is a function of x(t).

    Digital signals usually use PM as its possbile to formulate orthogonal codes which provide error correction capabilities in a noisy transmission channel.



    •   Alt28th August 2004, 10:31

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    Re: Diff bet FM and PM

    HELLO checkmate

    orthogonal codes which provide error correction capabilities in a noisy transmission channel


    plz ur word orthogonal codes are less prone to noise.............
    what about antipodal signals/codes...............



    •   Alt6th October 2005, 07:56

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  4. #4
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    Re: Diff bet FM and PM

    hi frd

    there is a basic difference betweem FM and PM

    in FM, modulation index is inversely proportional to the modulating frequency but

    in PM that is independent of the modulating frequency.

    regards

    puneet bansal



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