What is Modulation Index in AM? | New Topic [2024]

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Author Name: Arun Paul.

What is Modulation Index in AM?

The Modulation Index (or modulation depth) is an important parameter in amplitude modulation (AM) that determines the amount of modulation applied to the carrier wave. It denotes the ratio of the amplitude of the modulating signal (message signal) to that of the carrier wave. It is denoted by “m”.

Mathematical expression of Modulation Index

m = (A_m/A_c)

where,

• A_m = maximum amplitude of the modulating signal.
• A_c = maximum amplitude of the carrier signal.

Interpretation of Modulation Index

• Under Modulation: When 0 < m < 1
• Perfect Modulation: When m = 1
• Over Modulation: When m > 1