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Compare between FM and PM 
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PARAMETERS
FM
PM
1. Variable parameter of carrier.
Frequency
Phase
2. Variable parameter proportional to modulating voltage. 
Frequency deviation
Phase deviation. 
3. Amplitude of modulated signal.
Constant
Constant. 
4. Noise immunity 
Best of all schemes
Better than AM
5. Coverage area for transmitted power
More
Moderate
6. Signal to noise ratio
Best
Better
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