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Communication Systems - Engineering

Q1:

If e = 10 cos (2p x 108t + 20 cos 2p 103t). The bandwidth is

A 108 Hz

B 42 kHz

C 21 kHz

D 108 ± 103 Hz

ANS:B - 42 kHz

Modulation index = 20,
wm = 2 * 3.14 * fm, fm = 2 * 3.14 * 10^3/2 * 3.14 = 10^3.
Bandwidth = 2(modulation indx + 1)fm, 2(20+1) * 10^3 = 42khz.