Question
Define modulation index. Why is it kept low ? What is the role of a bandpass filter?
Solution
Modulation index is the ratio of the amplitude of modulating signal to that of carrier wave.
Modulation index is kept low in order to avoid distortion. The low frequency modulating signal is mixed with high-frequency carrier wave, the distortion is restricted due the high-frequency carrier wave for modulation index lying between 0 and 1.
Bandpass filter rejects low and high frequencies and allows a band of frequencies to pass through.
