1. The equipment used to generate and broadcast radio-frequency electromagnetic waves for communication purposes. In transmitted-carrier transmission it consists of a carrier-wave generator, a device for modulating the carrier wave in accordance with the information to be broadcast, amplifiers, and an aerial system. In suppressed-carrier transmission, the carrier component of the carrier wave is not transmitted; one sideband (single-sideband transmission) or both sidebands (double-sideband transmission) are transmitted and a local oscillator in the receiver regenerates the carrier frequency and mixes it with the received signal to detect the modulating wave.

2. The part of a telephone system that converts sound into electrical signals.