Which type of modulation involves varying the amplitude of a carrier signal in accordance with the intelligence to be transmitted?

Amplitude Modulation (AM) is the process of varying the amplitude of a carrier signal in direct proportion to the intelligence or information signal that is being transmitted. In AM, the frequency of the carrier wave remains constant while its amplitude changes according to the amplitude of the input signal, such as audio or data. This means that the peaks of the carrier wave become higher or lower depending on the variations in the information being sent.

This technique is commonly used in various forms of communication, including radio broadcasting, where audio signals are transmitted over long distances. The ability to alter the amplitude allows receivers to decode the information by detecting changes in signal strength, which translates back to sound or data.

In contrast, Frequency Modulation (FM) involves varying the frequency of the carrier wave rather than its amplitude, while Pulsed Modulation and Phase Modulation alter different aspects of the signal entirely. Understanding the distinct processes involved in these modulation techniques is important in fields such as telecommunications and signal processing.