What is frequency deviation in signal modulation?

Frequency deviation in signal modulation refers specifically to the amount and rate at which a signal deviates from its center frequency. In the context of frequency modulation (FM), this concept is essential as it determines how much the frequency of the carrier wave varies in response to the amplitude of the input signal.

When a signal is modulated, the carrier frequency is shifted from its rest position to carry information. The extent to which this carrier frequency shifts is what we describe as frequency deviation. It influences the bandwidth of the modulated signal and affects the quality and fidelity of the transmission. A greater deviation allows for the transmission of more information but may also increase the potential for interference and distortion.

Understanding frequency deviation is crucial for analyzing modulation techniques and their effectiveness in communication systems. In contrast, the total frequency range, instantaneous frequency change, and average frequency do not specifically address how the signal shifts relative to its central frequency as it carries information. Thus, option C encapsulates the definition accurately within the framework of signal modulation.