Frequency deviation calculation from FM equation

Calculate the maximum frequency deviation for the FM signal
v(t)= 10 cos(6000t+ 5sin2200t)

a) 2200 Hz
b) 6000Hz
c) 1750Hz
d) 11000Hz

Correct Answer: c) 1750Hz


A standard FM signal is represented by
v(t)= Ac cos(2πfct+ kfsin2πfmt)
Ac = carrier amplitude
fc= carrier frequency
kf= modulation index
fm = modulating frequency = 2200/2π = 350 Hz
kf = frequency deviation/modulating frequency
5= freq deviation/ 350
Therefore, deviation= 5 *350
= 1750Hz
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