Type G Carrier Telephone System

Electric power is supplied by the oscillator at the active terminal.

The incoming voice-frequency signal wave and the carrier wave are impressed on a copper oxide varistor bridge to produce modulation. The carrier frequency is transmitted in this system, and hence the positions of the carrier frequency and voice frequency in Fig. 24 are interchanged.³⁸ Both sidebands are transmitted (Fig. 18). Demodulation occurs at the inert terminal in a copper oxide bridge circuit. When the person at the active terminal is not speaking, a carrier-frequency wave flows to the inert terminal so that, when the person at this terminal speaks, carrier is available for modulation. At each terminal the same copper oxide bridge circuit is used for modulation and demodulation and is sometimes called a modem.