Editing Carrier wave (section)

{{Short description|Sinusoidal wave without any modulation}}
[[Image:Modulated radio signal frequency spectrum.svg|thumb|upright=1.4|The [[frequency spectrum]] of a typical radio signal from an AM or FM radio transmitter. 
The horizontal axis is frequency; the vertical axis is signal amplitude or power. 
It consists of a signal (C) at the carrier wave frequency ''f''<sub>C</sub>, with the modulation contained in narrow frequency bands called [[sideband]]s (SB) just above and below the carrier.
The entire signal range is the [[Bandwidth (signal processing)|bandwidth]] (BW).]]

In [[telecommunications]], a '''carrier wave''', '''carrier signal''', or just '''carrier''', is a periodic [[waveform]] (usually [[sinusoidal]]) that conveys information through a process called ''[[modulation]]''. One or more of the wave's properties, such as amplitude or frequency, are modified by an information bearing signal, called the ''message signal'' or ''modulation signal''. The '''carrier frequency''' is usually much higher than the message signal [[frequency]]; this is because it is usually impractical to transmit signals with low frequencies over long distances (due to attenuation).

The purpose of the carrier is usually either to transmit the information through space as an [[electromagnetic wave]] (as in [[radio communication]]), or to allow several carriers at different frequencies to share a common physical transmission medium by [[frequency division multiplexing]] (as in a [[cable television]] system). 

The term originated in radio communication, where the carrier wave creates the waves which carry the information (modulation) through the air from the transmitter to the receiver. The term is also used for an unmodulated [[Emission (electromagnetic radiation)|emission]] in the absence of any modulating signal.<ref>[[Federal Standard 1037C]] and [[MIL-STD-188]]</ref>

In [[music production]], carrier signals can be controlled by a modulating signal to change the sound property of an audio recording and add a sense of depth and movement.<ref>{{cite web|author=Rory PQ|date=May 8, 2019|url=https://iconcollective.edu/modulation-tips/|title=What Is Modulation and How Does It Improve Your Music|website=Icon Collective|access-date=August 23, 2020}}</ref>