Question

The modulation index of amplitude modulation system is limited to unity because

• A. transmission requires higher power for higher values of modulation index
• B. modulated signal bandwidth is higher for higher values of modulation index
• C. demodulated signal is distorted while coherent receiver is used
• D. demodulated signal is distorted while envelop detector is used as receiver

Hint:

An important characteristic of amplitude modulation is that it works well for modulation index below 1, which prevents distortion during envelope detection.

Answer 1

The Correct Option is D

The modulation index in amplitude modulation (AM) is limited to unity because if it exceeds 1, it leads to overmodulation and distortion of the signal in a standard envelope detector. This distortion makes the demodulated signal at the receiver unreliable, making it difficult to recover the intended signal.