In radio communications, which method is commonly used to modulate signals?

In radio communications, the method that is often used to modulate signals is Frequency Modulation (FM). This technique varies the frequency of the carrier wave in accordance with the information signal being sent. The advantage of FM is its resilience to noise and interference, making it ideal for high-fidelity broadcasts such as music. It allows for better sound quality compared to amplitude modulation, particularly in environments with a lot of background noise.

While Continuous Wave (CW) is a form of radio transmission that uses a constant frequency and amplitude to transmit Morse code signals, it is not typically referred to as a modulation method for voice or music signals. Instead, it is more suitable for simple on/off keying in telegraphs and communication that requires less bandwidth.

Amplitude Modulation (AM) is another common method that varies the amplitude of the carrier wave. It is widely used for AM radio broadcasting, but it is more susceptible to noise which can degrade sound quality.

Single Sideband Modulation (SSB) is a refinement of amplitude modulation and is efficient in terms of bandwidth. It conveys information over a single sideband while eliminating the carrier, but it requires more complex equipment to demodulate the signals.

Thus, the method of modulation that is most commonly used, particularly