Carrier Wave

The carrier wave is a sine wave that is modulated by a message signal prior to transmission. The message signal modifies the carrier wave amplitude, frequency, or phase prior to transmission. During modulation, these characteristics may be varied individually or in combination. The modified carrier signal, also referred to as the modulated wave, is transmitted to a receiver.

The message signal data in the received modulated wave is recovered by removing the carrier signal through demodulation. In advanced communication systems, the carrier may be a moving signal, also known as a spread spectrum. When the characteristics of the carrier signal are deterministic and known by the receiver, virtually any type of carrier signal can be used.

The nominal frequency of the carrier wave is the carrier frequency. In frequency modulation, the carrier frequency is the center frequency.