What does modulation depth indicate in amplitude modulation?

Modulation depth in amplitude modulation is a critical parameter that indicates the extent of variation in the amplitude of the carrier signal as a result of the modulating signal. It quantifies how much the carrier signal's amplitude changes in response to the modulating signal, which conveys information.

When you consider how amplitude modulation works, the carrier signal is typically a constant wave that gets altered based on the amplitude of the incoming audio or data signal. Modulation depth expresses this alteration in percentage terms—specifically, it can be described as the ratio of the amplitude change caused by the modulating signal to the amplitude of the carrier signal itself.

This is essential because a higher modulation depth means that there is greater variation in amplitude, which can result in a stronger signal and potentially better quality of the transmitted information. Conversely, insufficient modulation depth may lead to a weak signal that does not effectively carry the information.

The other options relate to different aspects of signal characteristics. The frequency of the carrier wave refers to how many cycles occur in a second, which is not the same as the depth of modulation. The duration of the modulated signal pertains to how long the signal is active, while the average power level of the signal deals with overall power rather than the specific behavior of the