Amplitude Modulation Tool

AM Modulation Calculator

Calculate AM modulation index, percent modulation, sideband power, total transmitted power, and bandwidth from carrier and message values.

AM Index, Percent, Bandwidth, and Power

Calculate AM Modulation Index

Enter carrier and message amplitude to calculate AM modulation index, modulation percent, sideband power, total transmitted power, and AM bandwidth.

Carrier Amplitude

0.1100

Message Amplitude

0100

Carrier Power

01000 W

Message Frequency

kHz

050 kHz

Formula: modulation index m = message amplitude / carrier amplitude. Standard AM bandwidth is 2 x highest message frequency.

AM Modulation Formula

In standard amplitude modulation, modulation index m equals message amplitude divided by carrier amplitude. Percent modulation equals m x 100.

AM Modulation Index Meaning

Index	Meaning	Practical Note
Below 1	Under-modulated	Envelope remains clean but modulation depth is lower.
Equal to 1	100% modulation	Typical maximum target for standard AM.
Above 1	Over-modulated	Envelope distortion and unwanted emissions may occur.

AM Bandwidth and Power

Standard AM bandwidth is twice the highest message frequency. Total AM power is carrier power multiplied by 1 plus m squared over 2, where m is the modulation index.

Frequently Asked Questions

How do you calculate AM modulation index?+

AM modulation index equals message amplitude divided by carrier amplitude. A value of 1 means 100% modulation.

What is over-modulation in AM?+

Over-modulation happens when the modulation index is greater than 1. It can distort the envelope and create unwanted sideband energy.

What is the bandwidth of an AM signal?+

For standard AM, bandwidth is twice the highest message frequency because the signal has upper and lower sidebands.

What is a good AM modulation percentage?+

A common target is close to 100% without exceeding it. Lower values are under-modulated, while values above 100% are over-modulated.