Which method of modulation is commonly used in radio communications?

Sideband modulation, particularly Single Sideband (SSB) modulation, is commonly used in radio communications because it significantly increases the efficiency of the transmitted signal. In SSB, instead of transmitting the full amplitude and frequency of a carrier wave and both sidebands, only one sideband (either upper or lower) is transmitted. This allows for reduced bandwidth usage and power efficiency, making it ideal for long-distance communication, especially in HF (high frequency) bands.

When using SSB, voice signals are effectively encoded onto a carrier wave, maintaining intelligibility while minimizing the amount of power required for transmission. This is especially critical in amateur radio operations where power and bandwidth efficiency are paramount. Additionally, SSB allows the operator to have access to a greater number of channels, improving communication capabilities.

In contrast, other modulation methods such as frequency modulation and amplitude modulation can occupy broader bandwidths and may require more power for effective transmission over similar distances. Phase modulation, while useful in certain applications, is not as universally adopted in traditional radio communications as SSB. Thus, the prevalent use of sideband modulation in amateur radio stems from its effectiveness in maximizing communication performance while conserving resources.