Special Features:

A 5 baud reverse channel or a 75 or 150 baud secondary channel.

Properties:

An item which modulates and demodulates one or more electrical signals. It connects data terminal equipment to a communication line or network such as telephone, radio or telegraph. It may include the multiplexing and demultiplexing circuits, circuit amplifiers and source(s) of carrier frequency. For items designed for light signals, see modem, fiber optic.