Question

Why is modulation index kept low and what is the role of bandpass filter?

Answer 1

If the modulation index is greater than , that means the amplitude of the modulating wave is higher than that of the carrier wave. This causes over- modulation of the carrier wave which results in distortion. Thus, a low modulation index is always maintained.

Bandpass filter rejects low and high frequencies and allows a band of frequencies to pass through.