In amplitude modulation, the modulation index mu, is kept less than or equal to 1 because.

Options

A. ` m gt 1` , will result in interference between carrier frequency and message frequency , resulting into distortion
B. ` m gt 1` will result in overlapping of both side bands resulting into loss of information
C. `m gt 1` will result in change in phase between carrier signal and message signal
D. ` m gt 1` indicates amplitude of message signal greater than amplitude of carrier signal resulting into distortion

Answer

B, D

Explanation

The modulation index (m) of amplitude modulated wave is `m = (" amplitude of message signal" (A_(m)))/("amplitude of carrier signal" (A_(c)))`
If `m gt 1 , then A_(m) gt A_(c)`. In this situation , there will be distortion of the resulting signal of amplitude modulated wave . Maximum modulation frequency `(m_(f)) of AM` wave is
`m_(f) =(Deltav_(max))/(v_(m(max))) =("frequency deviation")/("maximum frequency value of modulating wave")`
If `m_(f) gt 1` , then `Delta v_(max) gt v_(m)` . It means , there will be overlapping of both side bands of modulated wave resulting into loss of information.