n. (context radio English) A method of sending information by modifying (modulating) the intensity (amplitude) of a carrier wave. Commonly abbreviated '''AM'''.
n. modulation of the amplitude of the (radio) carrier wave [syn: AM]
Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. In amplitude modulation, the amplitude (signal strength) of the carrier wave is varied in proportion to the waveform being transmitted. That waveform may, for instance, correspond to the sounds to be reproduced by a loudspeaker, or the light intensity of television pixels. This technique contrasts with frequency modulation, in which the frequency of the carrier signal is varied, and phase modulation, in which its phase is varied.
AM was the earliest modulation method used to transmit voice by radio. It was developed during the first two decades of the 20th century beginning with Roberto Landell De Moura and Reginald Fessenden's radiotelephone experiments in 1900. It remains in use today in many forms of communication; for example it is used in portable two way radios, VHF aircraft radio, Citizen's Band Radio and in computer modems. "AM" is often used to refer to mediumwave AM radio broadcasting.
Usage examples of "amplitude modulation".
We have amplitude modulation and frequency modulation, but our civilization, by convention, ordinarily just doesn't do polarization modulation.
Then he broadcast on old-fashioned amplitude modulation which a modern communicator would not pick up at all, and which therefore might be used by men in hiding.
Since the VOA is an AM (amplitude modulation) radio station, speech and music are encoded as fluctuations in the amplitude (intensity) of a radio-frequency carrier wave.
Cycling up and down the sine wave of her moods was a helpless oscillation that she hated, and anything Michel did in the way of amplitude modulation she appreciated.
Lieutenant Uhura believes she can use the particle generator on Deck Two to create a system using amplitude modulation of neutrinos.
The other two pulses have the exact same amplitude modulation as our own pulse.