In some communications, the radio signal consists of a carrier wave and two side band waves. The carrier wave has no information, it only carries the side bands during transmission. The two side bands carry all the information, be it voice or data, pitch and modulation. To increase the distance the waves can travel, one side band wave is removed, leaving a single side band. This provides more transmission power to the single sideband that remains. It there for travels farther, however removing the other side band causes a loss of control for pitch, which must be compensated for manually. It is derived from an older technology but is still used quite frequently today especially in CB radio. ( citizens band ).