Multitech MultiModem MT5634ZPX User Manual page 52

A
Analog signal: A waveform which has amplitude, frequency and
phase, and which takes on a range of values between its
maximum and minimum points.
Analog Transmission: One of two types of telecommunications
which uses an analog signal as a carrier of voice, data, video, etc.
An analog signal becomes a carrier when it is modulated by
altering its phase, amplitude and frequency to correspond with the
source signal. Compare with digital transmission.
Application Program Interface (API): A software module created
to allow dissimilar, or incompatible applications programs to
transfer information over a communications link. APIs may be
simple or complex; they are commonly required to link PC
applications with mainframe programs.
ASCII (American Standard Code for Information Interchange)
(pronounced "askey"): A binary code for data that is used in
communications and in many computers and terminals. The code
is used to represent numbers, letters, punctuation and control
characters. The basic ASCII code is a 7-bit character set which
defines 128 possible characters. The extended ASCII file provides
255 characters.
Asynchronous Transfer Mode (ATM): A very high-speed method
of transmission that uses fixed-size cells of 53 bytes to transfer
information over fiber; also known as cell relay.
AT Commands: A standard set of commands used to configure
various modem parameters, establish connections and
disconnect. The "AT" is used to get the "attention" of the modem
before the actual command is issued.
Availability: The measure of the time during which a circuit is
ready for use; the complement of circuit "outage" (100% minus %
outage = % available).
B
Babble: unexpected bus activity that persists beyond a specified
point in a frame.
Backbone: 1. A set of nodes and their interconnecting links
providing the primary data path across a network. 2. In a local
area network multiple-bridge ring configuration, a high-speed link
to which the rings are connected by means of bridges. A backbone
may be configured as a bus or as a ring. 3. In a wide area
network, a high-speed link to which nodes or data switching
exchanges (DSEs) are connected. 4. A common distribution core
that provides all electrical power, gases, chemicals, and other
services to the sectors of an automated wafer processing system.
Background: An activity that takes place in the PC while you are
running another application. In other words, the active user
interface does not correspond to the 'background' task.
Bandwidth: the amount of data transmitted per unit of time,
typically bits per second (bps) or bytes per second (Bps).
Bell Operating Companies (BOC): The family of corporations
created during the divestiture of AT&T. BOCs are independent
companies which service a specific region of the US. Also called
Regional Bell Operating Companies (RBOCs).
Bell Pub 41450: The Bell publication defining requirements for
data format conversion, line conditioning, and termination for
direct DDS connection.
Bell Pub 62310: The Bell publication defining requirements for
data format conversion, line conditioning, and termination for
direct DDS connection.
Binary Synchronous Communication (BSC): A form of
telecommunication line control that uses a standard set of
transmission control characters and control character sequences,
for binary synchronous transmission of binary-coded data between
stations.
Multi-Tech Systems, Inc. MT5634ZPX User Guide
Bit (Binary digit): A bit is the basis of the binary number system.
It can take the value of 1 or 0. Bits are generally recognized as the
electrical charge generated or stored by a computer that represent
some portion of usable information.
Bps (bits per second): A unit to measure the speed at which data
bits can be transmitted or received. Bps differs from baud when
more than one bit is represented by a single cycle of the carrier.
Bridges: 1. A functional unit that interconnects two local area
networks that use the same logical link protocol but may use
different medium access control protocols. 2. A functional unit that
interconnects multiple LANs (locally or remotely) that use the
same logical link control protocol but that can use different
medium access control protocols. A bridge forwards a frame to
another bridge based on the medium access control (MAC)
address. 3. In the connection of local loops, channels, or rings, the
equipment and techniques used to match circuits and to facilitate
accurate data transmission.
Buffer: A temporary storage register or Random Access Memory
(RAM) used in all aspects of data communications which prevents
data from being lost due to differences in transmission speed.
Keyboards, serial ports, muxes and printers are a few examples of
the devices that contain buffers.
Bus: A common channel between hardware devices either
internally between components in a computer, or externally
between stations in a communications network.
Bus Enumeration: Detecting and identifying Universal Serial Bus
devices.
Byte: The unit of information a computer can handle at one time.
The most common understanding is that a byte consists of 8
binary digits (bits), because that's what computers can handle. A
byte holds the equivalent of a single character (such as the letter
A).
C
Call Setup Time: The time to establish a circuit-switched call
between two points. Includes dialing, wait time, and CO/long
distance service movement time.
Capabilities: Those attributes of a Universal Serial Bus device
that are administerable by the host.
Carrier Group Alarm (CGA): A T1 service alarm generated by a
channel bank when an OOF condition occurs for a predefined
length of time (usually 300mS to 2.5 seconds). The CGA causes
the calls using a trunk to be dropped and for trunk conditioning to
be applied.
Carrier signal: An analog signal with known frequency, amplitude
and phase characteristics used as a transport facility for useful
information. By knowing the original characteristics, a receiver can
interpret any changes as modulations, and thereby recover the
information.
CCITT (Consultative Committee for International Telephone
and Telegraph): An advisory committee created and controlled by
the United Nations and headquartered in Geneva whose purpose
is to develop and to publish recommendations for worldwide
standardization of telecommunications devices. CCITT has
developed modem standards that are adapted primarily by PTT
(post, telephone and telegraph) organizations that operate phone
networks of countries outside of the U.S. See also ITU.
Central Office (CO): The lowest, or most basic level of switching
in the PSTN (public switched telephone network). A business
PABX or any residential phone connects to the PSTN at a central
office.
Centrex: A multi-line service offered by operating telcos which
provides, from the telco CO, functions and features comparable to
those of a PBX for large business users. See also "Private Branch
Exchange", "Exchange".
Glossary
52