Which type of modulation is most commonly used for VHF and UHF voice repeaters?

Frequency Modulation (FM) is the type of modulation most commonly used for VHF and UHF voice repeaters due to its advantages in producing clear audio and its resistance to interference. Unlike Amplitude Modulation (AM), which can be more affected by noise and signal fading, FM maintains sound quality because it encodes information in the frequency of the carrier wave rather than the amplitude. This results in better audio clarity and increased range, making it well-suited for voice communication.

FM also occupies a wider bandwidth compared to AM, allowing for the transmission of higher fidelity audio signals, which is beneficial for conversations that require clear and understandable dialogue. The nature of VHF and UHF bands further complements FM, as these frequencies offer better propagation characteristics for repeater applications, facilitating communication over longer distances and around obstacles by utilizing repeaters to boost signals.

In contrast, Single Sideband (SSB) modulation is typically used in HF communications for its efficiency and reduced bandwidth use, PSK (Phase Shift Keying) is used mainly for digital communication, and AM, while it can be used, is not as effective as FM in the VHF and UHF ranges for voice. Therefore, FM stands out as the preferred choice for voice communication in these