SSB

SSB stands for single-sideband modulation, a form of amplitude modulation used in radio communications to improve spectrum and power efficiency. In conventional AM, the carrier and both upper and lower sidebands are transmitted, occupying more bandwidth and wasting transmitter power on the carrier. SSB removes one of the sidebands and suppresses most of the carrier, leaving a single sideband that contains all the information.

The technique relies on filtering the signal so that only one sideband remains and a small carrier may be reinserted at the receiver to aid demodulation. Demodulation typically uses a product detector or a Beat Frequency Oscillator to recreate the carrier, after which standard audio processing can be applied. Because the transmitted spectrum is narrower, SSB can carry voice or other data over a given channel with roughly half the bandwidth of conventional AM and with more efficient use of transmitter power.

There are two primary modes: Upper Sideband (USB) and Lower Sideband (LSB). USB is commonly used for frequencies above about 10 MHz, while LSB is often employed below that range, though practical choices can vary by band plan and equipment.

History and use: SSB was developed in the mid-20th century and became widely adopted in long-distance and military communications due to its efficiency. It remains standard in many amateur radio bands, shortwave broadcasting, aviation and marine communications, and other applications requiring reliable, bandwidth-efficient transmission.

Advantages include reduced bandwidth and better power efficiency, enabling more channels within a given spectrum. Disadvantages involve greater transmitter and receiver complexity and a need for precise tuning and frequency stability to maintain intelligible reception.