Motorola 326X V.34 ユーザーズマニュアル

Glossary-1

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

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.

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.

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.

Data without an accompanying time signal. Timing is derived from the asynchronous data 
with character boundaries defined by start and stop bits.

Automatic answering. A modem responds to an incoming call over a dial line and 
establishes contact with a remote modem.

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).

A method of coding digital signals using five bits to generate 58 different characters.

See Baud.

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.

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.

A base two numerical representation system using two digits, 0 (zero) and 1 (one); in the 
case of a computer, Off and On.

A blend of the two words binary and digit. The smallest unit in a byte of information, 
expressed as 0 (zero) or 1 (one).

A communications protocol or transmission procedure in which control information is 
encoded in fields of one or more bits. Compare with Character-Oriented.

(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. 

The rate at which data passes over the telephone line, in bits per second.