amplitude modulation: see modulation modulation, in communications, process in which some characteristic of a wave (the carrier wave) is made to vary in accordance with an information-bearing signal wave (the modulating wave); demodulation is the process by which the original signal is recovered from
..... Click the link for more information. ; radio radio, transmission or reception of electromagnetic radiation in the radio frequency range. The term is commonly applied also to the equipment used, especially to the radio receiver.
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AM

in full amplitude modulation

Variation of the amplitude of a carrier wave (commonly a radio wave) in correspondence to fluctuations in the audio or video signal being transmitted. AM is the oldest method of broadcasting radio programs. Commercial AM stations operate in the frequency range of 535 to 1605 kHz. Because radio waves of these frequencies are reflected back to the Earth's surface by the ionosphere, they can be detected by receivers hundreds of miles away. In addition to commercial radio broadcasting, AM is also employed in short-wave radio broadcasts, and in transmitting the video portion of television programs. See also FM.

amplitude modulation

Varying the voltage of a carrier or a direct current in order to transmit analog or digital data. Amplitude modulation (AM) is the oldest method of transmitting human voice electronically. In an analog telephone conversation, the voice waves on both sides are modulating the voltage of the direct current loop connected to them by the telephone company.

Modulate a Carrier
Amplitude modulation (AM) is also widely used to alter a carrier wave to transmit data. For example, in AM radio, the voltage (amplitude) of a carrier with a fixed center frequency (the station's channel) is varied (modulated) by the analog audio signal.

AM is also used for digital data. In quadrature amplitude modulation (QAM), both amplitude and phase modulation are used to create different binary states for transmission (see QAM). AM is also used to modulate light waves in optical fibers. See modulation and carrier.

Vary the Amplitude

In AM modulation, the voltage (amplitude) of the carrier is varied by the incoming signal. In this example, the modulating wave implies an analog signal.

Digital Amplitude Shift Keying (ASK)

For digital signals, amplitude shift keying (ASK) uses two voltage levels for 0 and 1 as in this example.

amplitude modulation [′am·plə‚tüd ‚maj·ə′lā·shən]

(electronics)

Abbreviated AM.

Modulation in which the aplitude of a wave is the characteristic varied in accordance with the intelligence to be transmitted.

In telemetry, those systems of modulation in which each component frequencyfof the transmitted intelligence produces a pair of sideband frequencies at carrier frequency plusfand carrier minusf.

(communications)

Amplitude Modulation - (AM) A method of encoding data by varying the amplitude of a constant frequency carrier.

Contrast Frequency Modulation.

Amplitude Modulation

a variation in the amplitude of oscillations (electrical, mechanical, and others) which takes place at a frequency much lower than the frequency of the oscillations themselves. Amplitude modulation is

Figure 1. Harmonic oscillation at a high frequency ω is modulated in amplitude by a harmonic oscillation at a low frequency Ω (τ=1/Ω—itsperiod), t is time, A is the amplitude of the high frequency oscillation, and T is its period.

used in radio technology—for example, in broadcasting. Sound vibrations are converted into electrical oscillations of low frequency Ω (the modulating signal) which periodically vary (modulate) the amplitude of the high frequency oscillations ω (the carrier frequency) generated by a radio transmitter (see Figure 1).

The amplitude-modulated oscillations are radiated in the form of radio waves that are intercepted by radio receivers, where the low frequency modulating oscillations are separated and converted back into an acoustic signal.

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Amplitude Modulation (redirected from Double sideband suppressed-carrier)

AM

Amplitude Modulation
(redirected from Double sideband suppressed-carrier)