Motorola 326X V.34, and V.32bis, V.34-SDC manual Glossary, Acu

Glossary

This glossary defines terms used in data communications and in the 326X Series Modem documentation set.

ACU	Automatic Calling Unit or Auto-Call Unit. Internal or external to the DCE, the ACU is a
	command set interface between the attached DTE and the modem that uses the normal DTE/
	DCE interface. The ACU allows for direct modem control and configuration by the DTE.
Analog signal	In data communications, a continuously varying signal (such as the human voice), which
	conventional telephone lines are designed to transmit. For transmission on these lines, the
	digital output from a computer or terminal must be converted to an analog signal.
ASCII	American Standard Code for Information Interchange. A method of coding digital signals
	using seven bits (or eight bits with parity) to generate 96 different characters.
Asynchronous	Data without an accompanying time signal. Timing is derived from the asynchronous data
	with character boundaries defined by start and stop bits.
Auto-answer	Automatic answering. A modem responds to an incoming call over a dial line and
	establishes contact with a remote modem.
Baud	The rate at which discrete signal elements are transmitted. In asynchronous transmission,
	baud rate=bit rate. In most synchronous transmissions, the baud rate is an integer submulti-
	ple of the bit rate. For example, in V.22 bis QAM modulation, four bits are sent in each
	baud. If the baud rate is 600, V.22 bis transmits at 2400 (600 x 4) bits per second (bps).
Baudot code	A method of coding digital signals using five bits to generate 58 different characters.
Baud rate	See Baud.
BCC	Block check character. A unique number derived from data transmitted in a block. The
	character is appended to data blocks for use in determining whether a block is received with
	errors.
BER	Bit Error Rate. The percentage of bit errors relative to a specific number of bits received;
	usually expressed as a number referenced to a power of 10.
Binary	A base two numerical representation system using two digits, 0 (zero) and 1 (one); in the
	case of a computer, Off and On.
Bit	A blend of the two words binary and digit. The smallest unit in a byte of information,
	expressed as 0 (zero) or 1 (one).
Bit-oriented	A communications protocol or transmission procedure in which control information is
	encoded in fields of one or more bits. Compare with Character-Oriented.
Block error	(1) A specified number of transmitted data bits over which an encoding procedure is applied
	for error-control purposes. A specified number of data characters or bits. (2) A quantity of
	transmitted information, or data, usually determined by its own starting and ending control
	characters.
bps	The rate at which data passes over the telephone line, in bits per second.

Glossary

Glossary-1