Difference Between Amplitude Modulation And Frequency Modulation

Difference between Amplitude and Frequency modulation:

Amplitude Modulation Amplitude of carrier wave is varied in accordance to message signal. Transmitted power depends on carrier power and modulation index. P(t)=P(c)[1+(u*u)/2] u=modulation index. P(t)=Transmitted power. P(c)=Carrier power. Bandwidth depends only on the message signal and is independent of modulation index. B.W=2*f(m) f(m)=message signal frequency. Range of frequencies is 550KHz-1650KHz Bandwith of each channel is 10KHz. A.M. propagates in ionospheric region.So it can be used globally. Frequency re use is not possible. Effect of noise is high. Linear modulation. Receiver is more simple. Efficiency is less.

Frequency Modulation Frequency of carrier wave is varied in accordance to message signal. Transmitted power is equal to carrier power and is independent of modulation index. P(t)=P(c) P(t)=Transmitted power. P(c)=Carrier power. Bandwidth depends not only on message signal but also on modulation index. B.W=2(1+B)f(m) f(m)=message signal frequency. B=modulation index.  Range of frequencies is 88MHz-108MHz Bandwidth of each channel is 200KHz. F.M. propagates in L.O.S. [ Line Of Sight.] It is limited to L.O.S. Frequency re use is possible. Effect of noise is very less. Non linear modulation Receiver is more complex. Efficiency is more.