Communications Systems Glossary

B channel.  The B channel si an integrated services digital network (ISDN) 64 Kbps bearer channel for pulse-code modulated voice or data.

Balanced-to-unbalanced converter (BALUN).  A balanced-to-unbalanced converter (BALUN) that converts between a balanced transmission line and an unbalanced line.

Balanced transmission.  Balanced transmission is a transmission mode in which signals are transmitted down a transmission line where the current travels down one conductor and returns on the other.

Band.  A band is a range of frequencies.

Band-limited signal.  A band-limited signal is a signal whose energy is totally contained within a finite frequency range (band).

Bandwidth (BW).  The bandwidth is the difference between the minimum and the maximum frequencies that can be passed by a communications system.

Baseband.  Baseband describes the transmission of signals without modulation. In a digital baseband network, binary values are transmitted directly onto the transmission line as voltage variations between two values.

Basic rate access (BRA).  Basic rate access describes an integrated services digital network (ISDN) connection consisting of two independent B channels (each 64 Kbps) and one D channel (16 Kbps).

Baud rate.  The baud rate is a measure of the number of symbols (characters) transmitted per unit of time.

Bayonet nut coupling connector (BNC connector).  Bayonet nut coupling connector (BNC connector) is a bayonet-style connector for coaxial cable.

Binary.  Binary describes a system having two states that are interpreted as a logical 1 or 0, or "on" or "off".

Binary coded decimal (BCD).  Binary coded decimal (BCD) is a coding scheme for the storage of data. The code was originally four-bit and latterly six-bit and later extended to become IBM’s EBDIC.

Binary frequency-shift keying (BFSK).  In binary frequency-shift keying (binary FSK or BFSK) the carrier is shifted between two frequencies.

Binary phase shift keying (BPSK).  Binary phase-shift keying (binary PSK, or BPSK) is phase-shift keying (PSK) between two phase states, normally 180 degrees apart.

Bis.  The postscript "bis" is used to note the second version of an ITU standard (bis is French for two).

Bit.  The term bit is a contraction of binary digit.

Bit error rate (BER).  The bit error rate (BER) is the number of bits received in error over a selected period of time.

Bit rate.  The bit rate is the rate at which binary digits (bits) are transmitted.

Bit stuffing.  Bit stuffing is the insertion of extra bits into a data stream to avoid the appearance of unintended control sequences that may interfere with a data frame.

Bits per second (bps).  Bits per second is the number of bits transferred in one second.

Block code.  A block code is an error detecting codes where the data is formed into blocks and processed to produce additional information.

Bose-Chaudhuri-Hocquenghem code (BCH codes).  A Bose-Chaudhuri-Hocquenghem code is a powerful error-correcting code that is an important subclass of cyclic block codes.

Bridge.  A bridge is a data-link layer (Layer 2) device that interconnects two local area networks (LANs).

Bridging router (Brouter).  Bridging router (Brouter) is a term used to describe bridges that are able to connect two LANs using different data link protocols by providing a limited routing function.

Broadband.  The term broadband is used to describe a broad range of frequencies. In communications systems, broadband can also be used to describe a high-capacity communications system.

Broadband integrated services digital network (BISDN).  The broadband integrated services digital network (broadband ISDN, or BISDN) is normally associated with the future telecommunications systems based on asynchronous transfer mode (ATM).

Broadcast.  To broadcast is to send the same message to a number (normally all) of the network terminals simultaneously.

Broadcast address.  A broadcast address is a common address that is used to direct (broadcast) a message to all terminals in a network.

Broadcast message.  A broadcast message is a message directed (broadcast) to all users on a network.

Bus topology.  A bus is a common shared communications medium for transmitting data.

Byte.  A byte is a group of 8 bits.

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