B: See byte.
B8ZS: Bipolar 8-Zero Substitution, (line code);A baseband line code in which ones and zeros are encoded with oppositeparities and every consecutive of eight zeros is replaced with a specialnon-all-zero sequence.
BackgroundNoise: A random noise in front of, and external to, a receiver.
Balance Condition: The conditionin which a hybrid circuit is most effective at separating transmitted andreceived signals.
Bandwidth: The frequency band size ofa signal.
Baseband: Data symbols that are sent tothe channel without modulation.
Baud: The unit in which the information carryingcapacity or "signalling rate" of a communication channel is measured. Onebaud is one symbol (state-transition or level-transition) per second. Thiscoincides with bits per second only for two-level modulation with no framingor stop bits.
Baud Rate Equalizer: Adaptivechannedl equalizer operating at the symbol of baudrate.
BBN: Bolt, Beranek & Newman, Inc.; Awardedthe original contract to build the ARPANETand have been extensively involved in development of the Internet.
B Channel: Bearer Channel; In ISDN,a full-duplex, 64-kbps channel used to send user data.
BCH: Bose, Chaudhuri, and Hocquenghem, (linecode); A class of cyclic codes that is easyto define and implement.
BDA: Broadcast Designers Association
BDSL: Broadband Digital Subscriber Line
BER: Basic Encoding Rules
BER: Bit Error Rate; A performance measurement,usually in terms of the number of errors per second, of a transmissionsystem.
B-Frames or B-Pictures:Bidirectional pictures; Pictures that use both future and past picturesas a reference. This technique is termed bidirectional prediction. B-picturesprovide the most compression. B-pictures do not propagate coding errorsas they are never used as a reference.
B-ICI: Broadband Inter Carrier Interface
B-ICI SAAL: B-ICISignaling ATM Adaptation Layer
BIND: Berkeley Internet Name Domain; Implementationof a DNS server developed and distributed by the Universityof California at Berkeley. Many Internet hosts run BIND, and it is theancestor of many commercial BIND implementations. (see the Domain NameSystem; DNS)
BIOS: Basic Input Output System
Biphase Line Code: A basebandline code with differenct phases for zeros and ones. (See alsoManchester line code)
B-ISDN: Broadband ISDN;A digital network with ATM switching operating at datarates in excess of 1.544 or 2.048 Mbps. ATMenable transport and switching of voice, data, image, and video over thesame infrastructure.
bit: (b) binary digit; The unit of information;the amount of information obtained by asking a yes-or-no question; a computationalquantity that can take on one of two values, such as true and false or0 and 1; the smallest unit of storage - sufficient to hold one bit.
Bit stuffing: Inserting an extra numberof bits to adjust the frame size.
block: A block is an 8-by-8 array of pelvalues or DCT coefficients representing luminance orchrominance information.
BMRC: Berkeley Multimedia Research Center;http://bmrc.berkeley.edu
BOC: Bell Operating Company; The local telephonecompanies that were created as a result of the breakup of AT&T.Also referred to as Regional Bell Operating Company (RBOC).
BOF: Birds Of a Feather; also 'Boring Old Fart'.
BOOTP: BOOTstrap Protocol
BPDU: Bridge Protocol Data Unit
BRA: Basic Rate Access; ISDNaccess service provides two B channels at 64 kbps each and a D channelat 16 kbps.
BRI: Basic Rate Interface; The lowest levelof ISDN service,typically used to connect a terminal and telephone to the local ISDNswitch. The BRI provides two B channels for simultaneousvoice and data service, and one 16 Kb/s D channel,or Delta channel, for control. (BRI) ISDN commonlyreferred to as 2B+D.
Each B channel can operate at a speed of upto 64 kbs and the D channel operates at 16 kbs.The B channels are used for
customer information in the form of Voice, Data, Images, Video andAudio. The D channel is used primarily for out of band
signalling but can also be used for low speed packet data. ISDNservice is subscribed to and provided by the telephone
company by making use of their digital network and by using specialequipment and software in a growing number of their digital
switches. The predominant signalling protocal used over an ISDNline is called 2B1Q (2 Binary 1 Quarternary). Thisis a four
level line code associating a pair of bits with a single quarternarysymbol (quat). Simply stated, the 2B1Q protocal represents
four voltage levels: +3v, +1v, -1v and -3v. ISDNallows for the "bonding" of the B Channels into one circuit which providesa
full 128 kbs channel suitable for high speed data transmission, Desk-topVideo Conferencing, etc..
The pair of wires running from your local Central Office to your homeor business (Local Loop) must be non-loaded. The
reason for this is that before ISDN, in the POTSworld, most of the Local Loops had load coils introduced to filter outany
signals that were outside of the voice frequency band (300 to 4000cps). These signals were considered to be "noise".In the
digital world, since analogue noise is no longer a factor, these loadcoils simply limit the bandwidth of a digital signal and prevent
the transmission of the higher speed signals associated with ISDN.In addition, the distance between your local Central Office
and your home or business can not exceed 18,000 feet (approx. 3.5 miles).In most urban locations this is not an issue but in
some rural locations, this can become a factor in the availabilityof ISDN and will require a special design.
Brickwallfilter: An ideal filter frequency repsonse with 0 loss passband,infinite loss stopband, and no transition region in between.
Bridged taps: Unused twisted-paricables attached to a telephone subscriber loop.
broadcast: Data packet that will be sentto all nodes on a network. Broadcasts are identified by a broadcast address.Compare with multicast and unicast.See also broadcast address.
broadcast address: Special addressreserved for sending a message to all stations. Generally, a broadcastaddress is a MAC destination address of all ones. Comparewith multicast address and unicastaddress. See also broadcast.
Broadcaster's Caucus: Thisis a group made up of ABC, CBS, FOX, NBC, PBS, NAB andMSTV with the goal to protect the broadcaster's interestas rule making is developed for ATV. It has been workingto develop a way to assign channels for ATV that willtreat existing broadcasters fairly and prevent interference to NTSCstations during the transition period to ATV.
BSD: Berkeley Software Design; BSD is alsosynonymous with a family of versions of Unix, distributed by BSD. Originallydeveloped as a Unix for the DEC VAXand PDP-11 computer systems. Also formed the kernel base for SunOS (SUN),Ultrix (DEC), and LINUX among otherUnix systems. (formerly known as Berkeley Software Distribution).
BSDI: Berkeley Software Desgn, Inc.
BSP: Binary Space Positioning
BSS: Broadcast Satellite Service
BSS: Business Support System
BWAN: Broadband Wide Area Network; (WAN)
BwD: Bandwidth Delay
B-Y: Blue minus Y (luminance), see B-Y,R-Y.
B-Y, R-Y: The basic video color-differencepair (pronounced "B minusY, R minusY"). The difference between a color and luminance:red - luminance and blue - luminance. The signals are derived fromthe original RGB source (e.g. a camera).
The Y, (B-Y), (R-Y) signals are fundamentalto much of television. For example in CCIR-601it is these signals that are digitised to make 4:2:2component digital video, in the PAL and NTSCTV systems they are used to generate the final compositecoded signal and in DTV they are sampled to create theMPEG-2 video bitstream. (see also, 4:2:2,NTSC, Y, Cr,Cb,YIQ, YUV)
byte: (B), A unit of datarepresentation usually larger than a bit and smallerthan a word. This day and age a byte ismost often represented by eight bits; which arethe smallest addressable units of storage. A byte typically holds one character.e
Byte: One of the first personal computer magazines.http://www.byte.com/
byte-aligned: A bit in a coded bitstream is byte-aligned if its position is a multiple of 8-bits from thefirst bit in the stream.