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Communication Systems - Engineering

Q1:

An FM transmitter has maximum frequency deviation of 75 kHz and reproduces audio signals up to 15 kHz. Minimum channel width required is __________ kHz.

A 180

B 120

C 90

D 60

ANS:B - 120

Modulation index is ratio of fd to fm.

fd = 75khz, fm = 15khz.

So, modulation index is 3.

Minimum channel required is bandwidth = 2(modulation index + 1) fm.
= 2(3 + 1) 15khz.
= 120khz.