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A/I) Converter: A circuit that converts signals from analog form to digital form.

Address: The number dialed by a calling party which identifies the party called. Also a location or destination in a computer program.

Aliasing: The occurrence of spurious frequencies in the output of a PCM system that were not present in the input, due to foldover of higher frequencies.

AM (Amplitude Modulation): A technique for sending information as patterns of amplitude variations of a carrier sinusoid.

Amplifier: An electronic device used to increase signal power or amplitude.

Analog: Information represented by continuous and smoothly varying signal amplitude or frequency over a certain range, such as in human speech or music.

Asynchronous: Refers to circuitry and operations without common timing (clock) signals. Attenuation: The decrease in power that occurs when any signal is transmitted. Audio Frequency: Frequencies detectable by the human ear, usually between 20 and 15,000 Hz. Bandwidth: The range of signal frequencies that a circuit or network will respond to or pass.

Base Unit: The transmitter (antenna and equipment), in a fixed location, and usually having higher power than the mobile units.

Binary Code: A pattern of binary digits (0 and 1) used to represent information such as instructions or numbers.

Bipolar: Having both positive and negative polarity.

Bit: An acronym for binary digit; the smallest piece of binary information; a specification of one of two possible alternatives.

BORSCHT: An acronym for the functions that must be performed in the central office when digital voice transmission occurs: Battery, Overvoltage, Ringing, Supervision, Coding, Hybrid, and Test. Byte: A group of X bits treated as a unit. Often equivalent to one alphabetic or numeric character.

Cable: An assembly of one or more conductors insulated from each other and from the outside by a protective sheath.

Cell: In cellular mobile telephony, the geographic area served by one transmitter. Subscribers may move from cell to cell.

Central Office (CO): The switching equipment that provides local exchange telephone service for a given geographical area, designated by the first three digits (NNX or NXX) of the telephone number. Channel: An electronic communications path, usually of 4,000 Hz (voice) bandwidth.

Circuit: An interconnected group of electronic devices, or the path connecting two or more communications terminals.

Common Battery: A system of supplying direct current for the telephone set from the central office. Compander: An acronym for COMpressor-ExPANDER, a circuit that compresses the dynamic range of an input signal, and expands it back to almost original form on the output. Crossbar Switch: An electromechanical switching machine utilizing a relay mechanism with horizontal and vertical input lines (usually 10 by 20), using a contact matrix to connect any vertical to any horizontal.

Crosspoint: The element that actually performs the switching function in a telephone system. May be mechanical using metal contacts, or solid-state using integrated circuits.

Crosstalk: Undesired voice-band energy transfer from one circuit to another (usually adjacent.) Current: The flow of electrical charge, measured in amperes.

Cut-Off Frequency: The frequency above which or below which signals are blocked by a circuit or network.

D/A Converter: A circuit that converts signals from digital form to analog form.

 

UNIX A multi-user operating system designed by Western Electric for large-scale corporate use.

User training Documentation designed to make learning easy. User training can include actual classroom study.

VDU Stands for video display unit (CRT and associated equip­ment).

ViaNet A system that consists of two or more MS-DOS, PC-DOS, or UNIX computers interconnected by cable.

Videotex Software designed to allow access to mainframe com­puters by using a terminal and a telephone modem.

Winchester Disk drive with a nonremovable hard disk inside. Winchester hard disks vary in capacity from several million bits of information to hundreds of millions.

Word processing Typing, editing, formatting, and storing of text by means of computer equipment. Word processing is a popular business application.

 

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