amplitude modulation

noun

1. one of the principal methods of transmitting audio, visual, or other types of information using radio waves, the relevant signal being superimposed onto a radio-frequency carrier wave. The frequency of the carrier wave remains unchanged but its amplitude is varied in accordance with the amplitude of the input signal AbbreviationAMam Compare frequency modulation
2. a wave that has undergone this process

amplitude modulation

1. A method of transmitting signals, such as sound or digital information, in which the value of the signal is given by the amplitude of a high frequency carrier wave. In AM radio transmission, for example, the signal to be carried is a sound wave, and its increasing and decreasing value is reflected in the increasing and decreasing amplitude of the radio frequency carrier wave. In fiber optics, the carrier wave is a beam of light.
2. Compare frequency modulation

amplitude modulation

1. A type of radio signal in which the amplitude, or strength, of a radio wave is varied in order to carry information from a transmitter to a receiver. ( Compare frequency modulation (FM) .)

Example Sentences

It has been well documented that a song's volume, or loudness, over time -- what's known as "amplitude modulation" -- is relatively steady at 1-2 Hz.

From Science Daily

AM stands for amplitude modulation, used to transmit information in a radio wave.

From Los Angeles Times

The difference between AM, or amplitude modulation, and FM, or frequency modulation, involves how sound waves are encoded into a signal that can be picked up by receivers.

From Washington Times

At the time all radio was AM, which stands for “amplitude modulation.”

From Time

Pushing them up or down was called amplitude modulation: changing the loudness. 

From Forbes