Radio Experimenter Theory Notes

Single Sideband (SSB)

In an AM system the carrier wave itself does not contain any intelligence. What's known as sidebands exist on the carrier. Both sidebands are identical as they both result from the modulating frequency. Therefore, only one sideband needs to be transmitted to effectively communicate voice information and this transmitting of one sideband only is known as single side band. The sideband at the higher frequency side of the carrier is known as the Upper Sideband (USB) and that at the lower side of the carrier is known as (yes, you've guessed it), Lower Sideband (LSB).

While SSB is an efficient way of communicating, it requires specialist equipment and a little bit of knowledge by the person receiving the signal in order to tune it in correctly. SSB is also not really suitable for broadcasting music. On the HF bands, SSB is the most popular mode of communication for voice, data and still images.

| Amplitude Modulation (AM) | Frequency Modulation (FM) | Single Sideband (SSB) |