|NI-RFSA 18.1 Help|
|NI-RFSA 18.2.1 Help|
|NI-RFSA 19.1 Help|
The carrier wave is a sinusoidal wave that is modulated by a message signal, m(t), prior to transmission. The message signal modifies the carrier wave amplitude, frequency, or phase. The modulation process may vary these characteristics individually or in combination. The modified carrier signal, also referred to as the modulated wave, is transmitted to a receiver.
The process of demodulation recovers a replica of the original message signal from the carrier wave. In advanced communication systems, the carrier may be a moving signal, also known as a spread spectrum signal. Virtually any type of carrier signal can be used as long as the receiver knows the carrier signal characteristics.
The nominal frequency of the carrier wave is the carrier frequency. The carrier frequency is the center frequency of the spread spectrum signal.