carrier wave (CW)
The carrier frequency, Carrier Wave( CW), is the frequency at which signals to be modulated are modulated and transmitted or radiated from the transmitter.
The carrier frequency is normally a fixed frequency which, depending on the modulation method, is changed in its amplitude, phase or frequency in the rhythm of the modulation frequency. Thus, amplitude modulation changes the amplitude of the carrier frequency, frequency modulation changes its frequency, and phase mod ulation changes the phase of the carrier frequency.
Depending on the modulation concept, the carrier frequency can have full amplitude, but it can also be reduced in amplitude or even suppressed. With reduced and suppressed carrier, the carrier frequency is added back when the signal is demodulated. Methods with suppressed carrier are used, among others, in broadcasting for the transmission of the stereo signal and in television for the color carrier. In addition, the carrier frequency can have several subcarriers which are at the same distance from the carrier frequency.
There are also modulation methods in which the carrier frequency changes abruptly, as in the frequency hopping method( FHSS).