28-07-2012, 01:21 PM
Analog Modulation
Analog Modulation.ppt (Size: 402.5 KB / Downloads: 62)
Nonlinear modulation
Requires high bandwidth
Good performance in the presence of noise
Used in situations where BW is not a major concern and high SNR is required
FM is used in
High fidelity FM broadcasting
TV audio broadcasting
Microwave carrier modulation
Point-to-Point communications system
Power of angle modulation
Although instantaneous frequency and phase of u(t) is varied with time, The amplitude of Ac is always constant
Hence the power of PM and FM is constant
Independent of m(t) and
Modulation index of PM and FM
For sinusoidal m(t)
Phase modulation index :
Peak phase deviation
More phase shift for a large magnitude a
Frequency modulation index:
Peak frequency deviation
More phase shift for al large magnitude a and small frequency fm
In general, for non-sinusoidal m(t)
W is Bandwidth of m(t)