0049-1800-xxx 326X V.34, V.34-SDC and V.32bis Series Modem – USER’S GUIDE 02/23/2010
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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 submultiple 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.
