bantam tube A squat electron tube with a normal-sized base that was once commonly used in small ap-pliances or battery-operated mobile devices like por-table radios.. batch fIleA data fi
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demarcate the end of one communication or section
and the beginning of the next one, especially in
situ-ations where many people are sending information
through the same queue, such as a print queue or (2)
to identify the type of communication or the person
to whom it belongs
bantam tube A squat electron tube with a
normal-sized base that was once commonly used in small
ap-pliances or battery-operated mobile devices like
por-table radios Modem transistors have since made most
types ofvacuum tubes obsolete See acorn tube
bar code Identification, information, and
manage-ment code designed for optical scanning by a
read-ing device Black and white visual bar codes are
fa-miliar identifiers on consumer products They assist
the checkers in entering prices and adjusting
inven-tory databases Bar codes are frequently inserted on
postal letters and packages that have been optically
interpreted In fact, the information encoded into
video and audio discs is stored via bar codes
Bantam portA connecting interface used on Tl
sys-tems for interfacing with receive and transmit (e.g.,
DS 1inlout) or external timing sources, typically with
balanced 100- or 120-ohm termination
Amini-Ban-tammay be used on T1 daughtercards for
support-ing an external monitor In circuit testsupport-ing, the sleeve
on the Bantam connection may be used to ground the
circuit
Port Configurations - Bantam
Unlike RJ-45 (left) or bayonet-mountports (middle),
which have distinctive shapes, a Bantam port is very
simple and unassuming, just a small round hole (or
dual holes for receive and transmit connections).
bar generator A device used to generate horizontal
or vertical bars on an output device to determine and
adjust linearity
Baran, Paul (ca 1926- ) A Polish-born American
engineer, Baran is acknowledged as a significant
In-ternet pioneer He conceived a Distributive Adaptive
Message Block Network (a concept dubbed packet
switching by Donald Davies) while working at
RAND Corporation on U.S federal communications
infrastructure projects The core concept was to
cre-ate a decentralized system through which data could
flow in any direction such that if a part of the system
were lost, a portion ofthe system and the data would
survive
Baran worked briefly on the historic UNIVAC
com-puter project before it was taken over by the RAND
Corporation and, after jobs elsewhere, ended up at
RAND Baran's networking ideas were verbally
pre-sented at RAND Briefing B-265 in the summer of
1961 He subsequently authored a series of
memo-randa entitled "On Distributed Communications"
which were released beginning in 1964 Around the
same time, Davies appears to have been indepen-dently developing distributed network concepts
In the analog electronics world ofthe 1960s, Baran's idea was a far-fetched proposal, far ahead of its time (it was rejected as impossible by AT&T) As digital technology evolved, however, Baran's ideas became
a practical possibility and formed the essential inspi-ration and format for distributed networks that evolved into the Internet
Afuturoriented thinker, Baran also predicted the e-commerce and online entertainment explosions ofthe year 2000, long before personal computers, the In-ternet, and the World Wide Web even existed He pro-phetically described online comparison shopping from home through the use of product images and databases back in 1967
Baran founded a number ofcommercial ventures and co-founded the Institute for the Future He is a trustee ofthe IEEE History Center In April 2001, Baran was awarded the Franklin Institute's Bower Award and Prize for Achievement in Science See Davies, Donald; Internet.Anoral history ofBaran, transcribed
in October 1999, is available online through the IEEE History Center
Barbe, Jane The actor and singer whose voice has been heard by millions as the telephone voice that informs subscribers aboutchan~ednumbers ("This number is no longer in service '), disconnects, and other situations Barbe is heard on Bell and National Bureau of Standards systems and many national voicemail systems She has provided the voice for Electronic Tele-Communications, Inc 's Audichron time, temperature, and weather services since the mid-1960s Fans ofearly television shows have seen her on the popular game show "I've Got a Secret" and "The Mike Douglas Show."
Barclay box relay Ahistoric telegraphic relay which had better sound amplification and portability than conventional models
Barclay insulator A type of early glass utility pole insulator invented by John C Barclay It is a type of spiral groove insulator and is numerically identified
as CD 150 See insulator, utility pole
bare metal, down to the bare metal The essentials
of a machine or system The low level systems func-tions Programming "down to the bare metal" usu-ally means programming in assembly or machine lan-guage or hand-wiring a prototype breadboard bare wire A wire without any kind of protective or insulating cover The ends of insulated transmission wires are usually stripped of their covers to provide bare wire for a good electrical contact at a circuit junc-tion
Barge In A surcharge phone service or feature of a multiline subscriber service enabling someone (hope-fully in authority) to barge into specified lines and interrupt a call in progress It is a privilege that should not be used indiscriminately but may be important
in emergency situations See buttinsky
barge out To abruptly leave a call in progress barium ferrite Barium, a silver-white, malleable substance which, in combination with iron, produces
Trang 2media Methods of synthesizing barium ferrite
nanoparticles through precipitation and spray
pyroly-sis are being studied
Barkhausen, Heinrich Georg(1881-1956) A
Ger-man physicist and educator, Barkhausen worked for
Siemens&Halske and then accepted a professorship
in communications engineering at the Dresden
Tech-nical Academy in 1911 He founded the first global
college for weak-current engineering, work that was
fundamental to the evolution and application
ofelec-tron tube technology Barkhausen discovered the
Barkhausen effect in ferromagnetic materials and, in
collaboration with K Kurz, described
Barkhausen-Kurz oscillations See Barkhausen-Barkhausen-Kurz tube
Barkhausen effectAphenomenon described in 1919
by H Barkhausen when he was studying magnetic
and acoustic effects He observed that a slow,
con-tinuous increase in the magnetic field applied to a
fer-romagnetic material would result in discontinuous
increases in magnetization due to changes in
elemen-tary magnets in the increasing magnetic field This
suggested that magnetism was a phenomenon related
to the larger domain of a ferromagnetic substance as
opposed to being a discretely atomic function The
effect was sufficiently strong to be heard as clicking
sounds when amplified through a speaker
Barkhausen-Kurz oscillationsIn a vacuum tube,
oscillation of electrons by means of electrodes and
the grid through manipulation of the voltage across
the grid and the plate such that the electrons flow back
and forth between the filament and the plate This
phenomenon has practical applications for the
gen-eration of ultra-high frequency waves and aided in
developing the principles ofvelocity modulation See
Barkhausen-Kurz tube, electron tube, klystron
Barkhausen-Kurz tube, B-K tubeA technology
capable ofgenerating microwaves that was developed
around the same time as the magnetron, the
Barkhausen-Kurz tube is a triode vacuum tube with
the third element, the grid, operated at a high
posi-tive voltage with the plate at zero or negaposi-tive
volt-age This configuration produces an oscillating
mo-tion ofelectrons between the filament and plate The
tube dates back to the work of German scientists H
Barkhausen and K Kurz who described the
technol-ogy inPhysik ZeitV.21, 1920 By the mid-1930s,
there were a number of commercial vendors of B-K
tubes, which were used in research and military
sens-ing applications See Barkhausen, Heinrich Georg;
Kurz, Karl; magnetron
barometerAninstrument designed to measure
atmo-spheric pressure.Itis one ofthe tools commonly used
to evaluate and predict weather patterns Barometers
are incorporated into a number of other instruments
as well, most notably traditional altimeters Newer
altimeters sometimes incorporate Global Positioning
Service (GPS) capabilities
Barometers were important instruments in early
stud-ies of magnetism, particularly in Italy where
mem-bers of the Accademia del Cimento used barometers
in the 1660s to provide an airless environment to
stances were dependent upon air Unfortunately, the difficulties of creating a vacuum and manipulating the materials within the small area hindered them
!:~:!~\;~i;~:::~:::::~:S~::~:: :~:::l:~ ••
early as the 1600s, in which a glow or flash appears above the mercury in a barometric tube ifit is moved quickly or shaken The phenomenon is similar to that exhibited by neon light, although this was not known
at the time See barometer
barrel distortionAtype ofvisual aberration in which the outward comers of an image are contracted in-ward This may happen on a convex or concave sur-face (depending upon whether it is backlit or frontlit) and is noticeable on older, more highly curved moni-tors and television screens The opposite ofbarrel dis-tortion is pincushion disdis-tortion See keystoning
barretter, barreterA device whose resistance changes in relation to temperature The hot-wire barretter was devised in 1901 by R Fessenden to improve the technology that was then being used to detect radio waves The technology was incorporated into voltage-regulating devices consisting of a wire filament connected to the circuit in series contained within a gaseous envelope In conjunction with a waveguide, a barretter can be used to measure elec-tromagnetic power
BARRNetBay Area Regional Research Network.An association of university campuses and government research centers in the San Francisco area See BBN Planet
Bartholin, Rasmus(1625-1698) ADanish physicist and mathematician from the erudite medically in-clined Bartholin family, Bartholin followed the ex-ample of his father Caspar and brother Thomas and studied in Italy from 1653 to 1656
He is best known for his 1669 experiments with Ice-land spar, a transparent form of calcium carbonate with interesting birefringent properties Bartholin published his findings as Erasmi Bartholini in
Experimenta Crystalli Islandici Disdiaclastici and
followed them up with other scientific publications that included information about optics His was an important contribution, inspiring a number of other prominent scientists to study and mathematically de-scribe double refraction and its implications regard-ing our understandregard-ing of the nature of light
Bartholin (sometimes transcribed as Erasmus Bartholinus) had an interest in astronomy as well and described the path of a comet he observed in 1665, which is richly illustrated inTheatrum Cometum pub-lished in 1666 See Iceland spar, Nicol prism
Barton, Enos Melancthon(1840s-early 1900s) Bar-ton co-founded Western Electric with telegraph/tele-phone pioneer Elisha Gray He initially fonned a part-nership in 1868 with George Shawk Shawk rejected
an offer to partner with Gray, but Barton was inter-ested in Gray's ideas and Gray&Barton was formed
in 1869, evolving into the Western Electric Company
in 1872 It is the spiritual forerunner of today's
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Lucent Technologies Graybar Electric Company,
Inc., was spun off from Gray & Barton in 1925 in
order to provide electrical distribution See Gray&
Barton; Graybar Electric Company, Inc
base I Bottom; lower support portion; portion to
which something is bonded; substrate 2 In utility
pole insulators, the base may be smooth or may have
drip points, little knobs for the distribution of
stream-ing moisture 3.In layered semiconductor fabrication,
the beginning or bottom layer ofa component, which
is often a supporting substrate 4 In bipolar
semicon-ductor components, a thin region ofone type of
semi-conductor sandwiched between an emitter and a
col-lector ofanother type to form a dynamic environment
In the base region, excitable (highly mobile) electrons
act as minority carriers moving between the emitter
and collector See p-njunction 5 In chemistry, a
sub-stance that gives up hydroxide ions in solution
base filmA substrate for holding magnetic particles
as in audio and video tapes The materials used for
base film vary but generally have the characteristics
offlexibility, resistance to wear, and affinity for
hold-ing the magnetic coathold-ings that are applied to their
sur-faces
Base Information Digital Distribution System
BIDDS AU.S Air Force telephony communications
distribution network installed in the 1980s with
au-tomated functions such as directory and operator
as-sistance, reporting, record-keeping, and billing
Base Information Transport SystemBITS AU.S
AirForce military network system Information about
BITS is published on the Web as an aid to outside
contractors planning and installing military
informa-tion technology infrastructures
base insulatorA large support and insulating
struc-rure used on transmissions towers to insulate the
tower from the ground
base memoryjmgon The first block of memory,
con-sisting of640 kilobytes, in the older Intel-based
desk-top computers Base memory is now more generally
used to describe the typical or minimum memory with
which a system is sold to the enduser By early 2002,
base memory configurations of 256 or 512 Mbytes
wercommon
base rateI The basic rate without options or
value-added services 2 The basic charge per minute for
measured service
base stationI Amain transmitting and/or receiving
station or central switching station, often one which
serves as a junction between wireless and wireline
communications paths, or between broadcast signals
and cable subscribers 2 In mobile communications,
a fixed station within the transceiver system See
cel-lular phone 3.In Global Positioning Systems (GPS),
a receiver established in a known location to provide
reference data for differentially correcting rover files
Baseline data can be correlated with position data
from unknown locations collected by roving
receiv-ers to improve accuracy
basebandI A simple type of transmission in which
the signal is sent without altering it, as by
modula-tion, and which does not require demodulation
through modems to alter the signal at its destination
A transmission that is not segmented by frequency division (multiplexing) This basic signal is centered
on or near the zero frequency See sideband 2 Aone-channel or one carrier-frequency data network such
as Ethernet, that is alternately shared by the various peripherals, such as computers and printers, or allo-cated as requested See narrowband, Token-Ring Contrast with broadband
baseband modemThis phrase is an oxymoron, since
a baseband signal is one that has not been modulated and thus doesn't require a modem to demodulate it However, baseband modems do sometimes provide
an interface device with some simple translation ca-pabilities and may physically resemble standard mo-dems, hence the name Sometimes better termed a short haul modem, it is suitable for short distances
baseband repeaterA common main station repeat-ing system used to retransmit a signal and, in some cases, drop out selected channel groups, e.g., voice channels, before retransmission Over long distances with several legs, heterodyne repeating, which is less subject to loss or distortion from modulation and de-modulation, may be used in conjunction with base-band repeating to exploit the better properties of each method See baseband, heterodyne repeater
baseboard racewayA cable conduit or pathway along wall baseboards The raceway may run along the baseboards, or be built into them, so they won't
be seen Thus, wiring can be installed and hidden without tearing into the inner walls
baseline I In coordinate systems, a scale, often the horizontal X axis, that establishes a reference struc-ture on which related data can be depicted 2 In ra-dar, a line displayed to show the track of a scanning beam 3.In typography, an imaginary line extending through a font (horizontal in Roman and Cyrillic fonts) for alignment Desktop publishing software is not entirely standardized; some programs treat the base-line as the bottom edge ofnondescending letters, and others treat it as the first unit beneath the bottom edge
of these letters 4 In a Global Positioning System (GPS), a pair of stations for which simultaneous data have been collected
bash, bash shell, Bourne-again shellA popular, powerful, practical sh-compatible Unix command interpreter shell (command environment) released in the late 1980s by the Free Software Foundation Bash
is based on the Bourne shell, with some features from Korn (ksh) and C (csh) shells
BASICBeginner's All-purpose Symbolic Instruction Code An English-like programming language de-signed at Dartmouth College in the early 1960s that evolved from the Dartmouth Simplified Code (Darsimco) BASIC was created to provide a pro-gramming environment that was faster and easier to learn than FORTRAN or lower level languages like assembler or machine code BASIC was originally a compiled language that enabled students to write computer programs for the Dartmouth Time-Sharing System running on a General Electric (GE) main-frame computer
Trang 4software has increased dramatically since the early
days ofBASIC and more powerful programming
lan-guages have evolved (e.g., C/C++) Users no longer
have to program a computer to use one, and the
de-mand for fast, powerful software has necessitated the
use of other languages Thus, the original text-based
BASIC has largely faded into computer history,
sur-vived mainly by object-based graphical versions
(pri-marily Visual BASIC) that are useful for writing
utili-ties or prototyping software interfaces and software
flow (e.g., proofofconcept demonstrations) With so
much off-the-shelf software now available, the
mo-tivation for the general consumer to learn to program
in BASIC has all but disappeared, though
BASIC-like macro programming languages can still be found
in most paint, database, and word processing
pro-grams for the purpose of automating common tasks
See VisualBASIC
basic access authenticationSee authentication,
ba-sic access
basic cable serviceThe base service (lowest level)
offered by a television cable company, consisting of
a cable feed to the premises and broadcasting ofa
spe-cific package ofprograms The cable company's
pro-gramming provisions, signals, and public,
educa-tional, and government access channels are
govern-ment regulated under the Cable Act Rates for basic
cable services and equipment are regulated by
fran-chising authorities that are, intum,certified by the
Federal Communications Commission (FCC) FCC
rules are available through the International
Tran-scription Service (ITS) See Cable Act of 1984
Basic Call ModelBCM See Intelligent Networks
Call Model
Basic Control SystemBCS An interrupt-driven
computer satellite control system
Basic Encoding RulesBER Standardized rules for
data encoding that provide support for the abstract
syntax description language ofAbstract Syntax N
0-tation One (ASN.l) BER was developed in the
1980s, arising out ofISO X.409 and rewritten as ISO
8825 to provide a separation between ASN.l and
BER concepts It was then introduced in the 1988
CCITT Recommendations as X.209 and became a
tool for use in the development of open systems
architectures It became one of three major schemes
that evolved in the early 1990s for encoding and is
strong in the areas of extensibility and the ability to
recognize encoding structure without knowledge of
the originating ASN.l type See Abstract Syntax N
0-tation One, Packed Encoding Rules, LightWeight
Encoding Rules
Basic Exchange Radio Telecommunications
Ser-viceBERTS A system developed in the 1980s to
pro-vide wireless services through radio signals to
stan-dard local telephone loops, especially to rural areas
or for emergency services
basic information unitBIU In packet networking,
a unit of data and control information consisting ofa
request/response header (RR) and a following
re-quest/response unit (RU)
specified standard levels for services, transmission, and loss (8 dB in the 300 to 3000 Hz bandwidth) See Assured Link
Basic Rate InterfaceBRI There are two basic types
of ISDN service available: BRI and PRI BRI is an ISDN service consisting oftwo bidirectional 64 Kbps bearer channels (B channels) for voice and data and one delta channel (D channel) for signaling or packet networking at 16 Kbps or 64 Kbps It requires two conductors through a U Loop, from the carrier to a terminator (NT1) at the customer premises Except
in the rare cases of extremely long phone lines with load coils, most existing phone lines can be used for BRI without significant changes to the actual wire BRI is aimed at residential and small business users See ISDN
basic sequential access method BSAM A basic means of accessing data stored external to a proces-sor Other common methods includebasic direct ac-cess,andbasic partitioned access.
basic telecommunicationsA Federal Communica-tions Commission (FCC) general administrative cat-egory distinguished fromenhanced service telecom-munications.The concept applies to telecommunica-tions that are facilitated by computer technologies without additional processing or protocol conver-sions Basic phone service is one example This ser-vice is regulated under Title II and mainly affects tele-phone service carriers rather than those offering en-hanced computer data services As such, basic tele-communications providers may be subject to fees and regulations that don't apply to enhanced services pro-viders and are regulated in order not to stifle compe-tition with enhanced services providers Providers offering both basic and enhanced communications services have to maintain distinctions between basic and enhanced services when billing clients and mar-keting services to potential customers See Federal Communications Commission
Basic Trading AreaBTA.Anorganizational desig-nation for wireless telecommunications in which the United States is subdivided into almost 500 basic trading areas (BTAs) which are collectively grouped into Metropolitan Trading Areas (MTAs) The BTAs are used by the Federal Communications Commis-sion (FCC) as a basis for assigningpes wireless phone system licenses
basket windingA technique ofwinding a wire coil,
or other filamentous conducting material, such that the paths of the various turns of the winding do not touch except at junctions where they may cross It is sometimes called lattice winding
Basket winding is used in applications where a long length of wire, or a greater degree of surface area, needs to be organized into a small amount of space Basket wound antennas and other devices can be quite aesthetic, resembling arabesque See basket-wound tuners
basket-wound tunersHistorically, various types of basket winding with fine threadlike materials were commonly used in old radios to act as frequency
Trang 5Fiber Optics Illustrated Dictionary
tuners The windings were of many shapes,
cylindri-cal, circular, somewhat spherical They variedin
com-plexity from a dozen turns or so, to many hundreds
ofturns, in intricate patterns in many layers By
vary-ing the shape, size, and the thickness ofthe wires,
dif-ferent frequencies could be selected A radio often
came with a selection of basket-wound tuners with
electrical contacts on the base that could be plugged
in as needed
Basov, Nicolay Gennadiyevich(1922-2001)
ARus-sian medical assistant, physicist, and engineer, Basov
made important contributions to the field ofquantum
radiophysics and pioneered ammonia-based beams
(early laser research) By 1957, Basov was
design-ing and constructdesign-ing optical quantum oscillators that
had potential for gas and semiconductor-based
oscil-lators By the early 1960s, along with various
collabo-rators, Basov was creating injection semiconductor
lasers with gallium arsenide Through investigations
of short laser pulses, high-power single-pulse
Nd-glass lasers were developed in the mid- to late 1960s
In 1964, along with Townes and Prokhorov, Basov
was awarded a Nobel Prize Under Basov's guidance
in the early 1970s, an original chemical laser was
developed and Basov et al described infrared laser
stimulation of chemical reactions See laser.; laser
history; Townes, C
bassInaudio, a low pitch; a deep audible tone
bat switchSee toggle switch
batchAnassortment of data or objects grouped to
be processed during a single run ofa program or
pro-cess See batch file, batch processing
batch fIleA data file for grouping, storing, and
fa-cilitating the execution ofcomplex sequences or
fre-quently used computer commands Batch files are a
convenient way to store configuration parameters,
frequently used groups of commands, a list of
appli-cations that are executed one after another, commands
intended for deferred execution, scripts launched
from Web pages, and startup commands for a
com-puter system ".BAT" is a familiar extension given
to batch files on MS-DOS-compatible systems Many
systems provide job control languages (JCLs) or a
va-riety of scripting languages for the quick creation of
batch files Perl is an excellent multiplatform
pro-gramming tool for creating batch files use on and off
the Web Batch commands have traditionally been
created with text editors, but graphical tools may be
used See batch, batch processing, JCL, Perl, Java
batch processingDeferred or off-line processing of
an assortment of data, programs, or objects handled
during a single program or process run Unless there
is a fault condition, batch processing usually assumes
once the job is initiated, it will run undisturbed and
unattended Email is often handled as a batch process,
e.g., your Internet Services Provider may wait a
speci-fied period of time before posting a group of
mes-sages to your account rather than posting each one
as it is received Payroll accounts are often run as
batch processes, as are many data collection
pro-grams, such as weather testing, astronomical
obser-vations, etc
Itis not uncommon for batch processes to run as back-ground tasks, executing while users continue to use the system for other applications Batch processes can
be scheduled to run when network access is low, thus not putting a drain on system resources when many users are online Batch processes can also be used to schedule transmissions, such as facsimiles, during hours when phone rates are low See batch, batch file, realtime processing
Batch Simple Mail Transfer ProtocolBSMTP, bSMTP, Batch SMTP Abatch version of the Simple Mail Transfer Protocol developed in the early 1980s
by E Alan Crosswell to facilitate the reliable trans-mission ofelectronic mail messages over distributed computer networks independent of the transmission subsystem Batch SMTP allows a series ofcommands
to be bundled and sent to a remote machine for ex-ecution' rather than establishing a typical interactive SMTP session The processing of special characters may also be supported through batch processing This protocol was presented to the BITNET community
in 1982 and installed on many BITNET mailer gate-ways See Simple Mail Transfer Protocol See RFC 821,
batteryA group of two or more cells connected to-gether in such a way that they produce a direct elec-tric current (DC) While historians believe battery power may have been used for electroplating by the Parthians as early as the third century BC, the first significant records of modem battery experiments date from the work ofC A Volta
Battery-generated electricity was widely used in in-dustrial applications and telegraph and telephone communications in the early 1900s Edison was a strong proponent of DC current and received much opposition from Tesla and Westinghouse, who were advocating alternating current (AC)
Batteries are used widely in portable devices and as emergency or backup power for systems whose main power source is alternating current The Sampling of the Evolution ofBatteries chart describes a few com-mon batteries and interesting technological adapta-tions See B Battery, cell, storage cell, talking battery battery, rechargeableA direct current (DC) power source A rechargeable battery is designed to readily have its power restored, usually through consumer-priced battery chargers or through an alternating cur-rent (AC) transformer attached between the wall socket and a battery-charging device Rechargeable batteries are commonly used on palmtops, laptops, camcorders, etc Most of them need to be fully dis-charged before being redis-charged, or a memory effect results in only a partial charge Some can be trickle-charged when plugged into an outlet while being used Larger rechargeable batteries for consumer electronics usually supply from two to five hours of charge
battery, storageAtype ofbattery that, once charged, will hold that charge for a practical amount of time without constant electrical refreshes from another source, such as alternating current (AC) Car batter-ies are a type of common storage battery that are
Trang 6bazookaA device for isolating an outer conductor from other surfaces and connecting an unbalanced line to a balanced line Bazookas are commonly used
on the ends ofcoaxial cables that are to be connected
to two-wire lines (e.g., copper twisted pair) See balun
BB1 See baseband 2 See broadband
BNC connectors are widely usedfor couplingfiber optic and coaxial cables to switchers and patch pan-els, as they provide a secure connection that is not easily uncoupled by bumping or tugging End and overhead views ofa number ofcommon BNC (bayo-net mount) connectors are illustrated asfollows: BNC
to RCA plug (A), BNC to RCAjack (B), BNC to
screw-type F connector (C), BNC to dual BNC male
con-nectors (e.g., 'thin' Ethernet) (D), BNC terminator (E).
E D
c
BNC Connectors
B
A
Bauschinger effectStraining a solid body beyond its yield strength in one direction decreases its yield strength in other directions
bay 1 Harbor, indentation, arced enclosure 2 An opening in a rack or panel into which modular com-ponents can easily be inserted A patch bay has a se-ries of regular openings designed to securely hold modular components while still providing easy ac-cess, ease of configuration, and swapping in and out
as needed See patch bay 3 Part of an antenna array bayonet baseA type ofjack or jack-like base, as on
a bulb, which has a small projection on one side and slips into a receptacle with aturnso the projection catches within a small trough and secures the inserted object
bayonet nut connector, bayonet navy connector BNC A quick-connect bayonet-locking connector, commonly used for coaxial cables for network or video transmissions It is intended to provide a con-stant impedance The outer shell has a sma,ll bayonet that inserts in a helical channel in the receptacle to aid in firmly securing and aligning the connector This
is good for securing connections that must not be in-terrupted or for securing cables against which there may be tension See connector, F connector, RCA connector
useful life of about three to five years if not
com-pletely discharged too often (by leaving lights on, for
example) Storage batteries are often used as backup
systems for alternating current (AC) systems See
battery, fechargeable
battery backupA direct current (DC) backup
sys-tem which kicks in if something happens to the
pri-mary power system For example, many phones now
have memory storage for names and numbers, or
ex-tra features like speakerphones or text display, that
require more power than is provided by the current
coming from the phone line These phones may have
a battery or AC power cord to help power the extra
features which also functions as a backup battery to
protect the contents of the electronic phonebook if
the phone line power is interrupted by a power
fail-ure, or if the phone is disconnected and moved from
one location to another
Most computer systems have small batteries on the
motherboard to protect the contents of certain types
of chips that hold information such as configuration
parameters Lithium batteries are commonly used and
should be replaced every 5 to 7 years or so
Many microwaves, clock radios, and VCRs have
backup batteries so that the time is not lost during a
power outage Ifyour appliance flashes 12:00 after a
power failure, itprobably doesn't have a backup
battery
baud, baud rateAunit signifying a rate
oftransmis-sion of data indicating the modulation rate, named
after French engineer J.M.E Baudot The term is
commonly used to describe modem data transfer rates
(e.g., 9600 baud), although it originated from
tele-graph signaling speed in the 1920s Note that the rate
of transmission is not necessarily equal to the rate of
acquisition of the data Line interference,
handshak-ing' error correction, and other factors can cause the
actual rate of data received to be less than the raw
transmission speed associated with the amount ofdata
transmitted
Baudot,J M.Emile(1845-1903) A French
engi-neer and inventor, Baudot made many contributions
including a means, in the 1870s, to insert
synchroni-zation signals between baseband signals so time
di-vision multiplexing (TOM) could be used to combine
signals into a bundle He developed the Baudot code
for telegraphic communications
Baudot code, Murray codeA data code used in
asynchronous transmissions, named for its inventor
J M Emile Baudot.Itwas widely incorporated into
teletypewriter communications beginning around
1870 Baudot code was based on a marks and spaces
character-representation scheme employing five
equal-length bits to symbolize upper case letters A
simple method of reversing the polarity of the line
was in use for about half a century before it was
su-perseded by frequency shift keying (FSK modulation
techniques) The character set was very limited and
eventually standard codes such as EBCDIC and
ASCII superseded Baudot code except for
special-ized communications, asfo~the hearing impaired
Trang 7Fiber Optics Illustrated Dictionary
BBC 1.Broadband Bearer Capability A bearer class
field that is part of an initial address message See
ISDN.2.See British Broadcasting Corporation
BBL 1 broadband loop 2 BROADBANDLOOP
Project.AnACTS project to define and test
cost-ef-fective broadband access network concepts
facilitat-ing the migration of fiber optic transmissions into
local loops The project demonstrates the upgrade of
passive optical networks to high bandwidth capacity
and the upgrade of wire-based networks to handle
broadband services to the customer premises The
target group for the project is European residential
subscribers and small- to medium-sized businesses
See BIDS, BONAPARTE, BOURBON,
BROAD-BANDLOOP, UPGRADE, WOTAN
BBNBolt, Beranek, and Newman, Inc
Ahigh-tech-nology company in Cambridge, MA which
devel-oped, maintained, and operated the historically
sig-nificant ARPANET and later the Internet gateway, CSNET CIC, and NSFnet NNSC See BBN Planet BBN Planet A subsidiary of Bolt, Beranek, and Newman, Inc., which operates a national Internet access network See BBN
DBSSee bulletin board system
DBTbroadband technology
DcSee Committed Burst Size
BC 1 backward compatible 2 beam coupling 3 bi-nary code 4 broadcast
BCC 1 Bellcore Client Company 2 See block check character
DCDSee binary coded decimal
DCMSee Basic Call Model
DCOBBroadband Connection-Oriented Bearer In ATM networks, information in the SETUP message that indicates the type ofservice requested by the call-ing user The appropriate bearer class depends on the
Sampling of the Evolution of Batteries and Promising Battery Technologies
B battery
electrochemical Nogami et a1
Daniell battery J F Daniell
Edison cell
gravity/crowfoot cell
Grove battery
A battery
A chemical battery used in early telegraph systems, 1 volt
A variable storage nickel hydrate (positive) and iron oxide (negative) cell with an electromotive force lower than that of a lead cell This is a historic battery that was used in automobiles due to its ruggedness
Avoltaic wet cell for providing small currents at a constant emf Primary, 1.96 volts per cell Zinc, platinum Used by S Morse Historically used astalk batteriesin telephone installations and
as low voltage batteries for electron tube filaments Modem versions are now commonly used for cameras, calculators, and other small portable appliances
Historical provider of low voltage power to the plates (anodes)
in electron tubes and to communications relay circuits
Introduced in the early 1920s, C batteries provided bias voltage
to electron tubes for the control of the grid circuit and were often used in conjunction with B batteries to extend the life of the B battery C batteries are now commonly used with small portable devices such as flashlights and portable boomboxes
Announced by Bell in 1954, there are now a number of variations on this technology from different developers Kyocera introduced a multicrystal silicon solar battery in 1996 that has a conversion efficiency rate of 17.1%,considered good in the solar industry
Abattery chemistry based on lithium polymer which may provide longer life for power-hungry mobile phones, laptops, etc
Biological systems in the form of synthetic melanins that appear
to have the form of an amorphous semiconductor "threshold switch" operating at threshold significantly lower than inorganic thin films These also exhibit electroluminescence at the point of switching energy states, described in 1973
A battery with its electrodes immersed in an organic solvent electrolyte solution with the electromotive force generating by dopinglundoping processes associated with the electrodes, 1982 McGinness et al
Bell Labs
organic
C battery
silicon solar
lithiumnouveau
Trang 8BCOB-A (Type A) connection-oriented,
con-stant bit rate, timing required BCOB-C (Type C) connection-oriented, variable
bit rate, timing not required BCOB-X (Type X) transparentAAL, traffic type
and timing requirements UNI 3.0 and UNI 3.1 must support Type A and Type
C or Type X as a substitute for the first two types for
virtual connections (VCs) Internet Protocol over
ATM signaling must permit Type C and Type X
bearer capability in specified combinations Type C
and Type X both apply to multiprotocol connections
BCP See Best Current Practice
BCRS See Bell Canada Relay Service
BCS 1 basic control system 2 Batch Change
Supplement A development tracking system for
documenting system features from proposal to
fm-ished product 3 See beam control system 4 See
Boston Computer Society 5 See British Computer
Society
BDFblock data format, also referred to as data block
format (DBF) A generic phrase for a block ofdigital
data with a specific format with respect to the size
and order of the data items within the block
BDTSee Telecommunications Development Bureau
Be 1 See burst size, excess 2 See Be, Inc
Be,Inc.A computer software company founded by
Jean-Louis Gassee, head ofR&D at Apple Computer
during the Apple II years Be developed and released
the BeOS (Be Operating System) in 1997 It is a fast,
integrated-database, multiplatform OS aimed at the
audio and graphics/video computer-using markets In
addition to BeOS, Be now provides integrated
client-side software, development, and customization tools
for Internet device and service providers and
con-sumer electronics companies In the early 2000s, Be
was acquired by Palm See BeOS
BE 1 base embossed A designation for glass and
ceramic utility pole insulators with embossings on the
lower edge, usually of the size, company, and/or
patent date 2 Bose-Einstein
beacon1 Asignal, locator, or guidance beam or tone
2 A transmitter that aids in monitoring radiant
en-ergy propagation
beacon alertAn alert frame in a Token-Ring or
Fi-ber Distributed Data Interface (FDDI) device
signal-ing a serious problem, such as a physical
interrup-tion of the signal or Media Access Unit (MAU) The
frame includes information on the location of the
break or the station that is down
beam 1 n Aray,shaft, or other directed energy or
illumination, as an electron tube, radar, or light beam
2 v To direct or aim, as in a broadcast beam
beam antennaAn antenna that transmits and/or
re-ceives within a narrow, confined directional range
beam control systemBCS A means for directing a
beam It may also have control capability for turning
a beam on and off A BCS is usually used for
di-recting common electromagnetic beams such
as microwave radio signals or a beam of light, but it
physics testing systems (e.g., study ofneutrinos) The more sophisticated the technology, the more likely that beam control is automated with computer hard-ware and softhard-ware Logging of beam characteristics and activities over time may also be incorporated into aBCS
beam divergence 1 As a beam travels through the air, various factors may cause it to spread out This divergence may result in attenuation or dispersion of the signal strength of a transmission over distance
2 The path ofa beam may progressively move away from the axis of the original trajectory, resulting in divergence
beam position monitorBPM A mechanism for keeping track of the position of an emitted/transmit-ted beam of light (e.g., laser light) or other electro-magnetic energy (e.g., radio waves) Abeam position monitor is commonly used in systems where the di-rection of the beam can be controlled
beam power tubeAn electron tube with a beam that
is directed and concentrated in certain specific direc-tions by a special electrode Used, for example, in radio frequency (RF) transmitters
beam splitterA device that produces two or more separate beams from one incident beam Mirrors and prisms are commonly used to direct or split light beams Coherent laser light is favored for most beam splitting applications Once the beam is split, the split beams are usually ofa lower intensity than the origi-nal beam, in proportion to how many times the beam has been split Beam splitting is used in a number of industrial instruments and consumer devices and is also used for testing and diagnostic purposes
In interferometers, a beam is split into two or more beams in order to compare the relationship of the beams when they are recombined The interference patterns from the beams can provide information on influences from heat, vibrations, gases, etc
bearer channelSee B channel
beatShort percussive tone, one instance of a repeti-tive sequence, a reaction from the impact of one ob-ject or process on another, the interaction of two dif-ferent frequencies when certain portions of their cycles interact See beat frequency, beat reception, zero beat
beat frequencyThe frequency resulting when two different frequencies beat together on a nonlinear cir-cuit The beat frequency is equal to the difference between the two separate frequencies, typically ex-pressed in cycles per second (hertz) When the beats are very close to the same frequencies, they can be set to generate an audible tone which may change when subjected to the influence of magnetic materi-als See heterodyne
beat frequency oscillatorBFO A low-current gen-erator ofbeat frequencies in a nonlinear circuit BFOs are used in a number of practical applications from metal detectors, which use search and reference os-cillators, to older single sideband radio receivers
beat receptionThe combining of two different fre-quencies, usually the external, incoming frequency,
:?!.
:1 :
Trang 9Fiber Optics Illustrated Dictionary
and an internally generated frequency which are then
easier to amplify or othelWise condition as a single
frequency than the incoming frequency would be by
itself: See heterodyne For contrast, see zero beat
re-ception
beating A wave phenomenon that occurs when two
or more periodic waves ofdifferent frequencies
com-bine to form a periodic amplitude pulsation In
au-dio, beating can quite often be heard and felt as an
undulating pulse by those in listening range See beat
frequency, heterodyne
Beaufort notation In meteorology, a code used for
indicating the state of the weather
Beaver Falls Glassworks A lesser-known historic
utility pole glass insulator fabrication company
founded by William Modes in Pennsylvania in 1869
See insulator, utility pole
BEC 1 See Best Effort Capability 2 Bose-Einstein
condensation
BECN See Backward Explicit Congestion
Notifica-tion
beehive insulator A type of early glass utility pole
insulator, characterized by its beehive shape See
in-sulator, utility pole
BEEP Ageneric application protocol framework for
connection-oriented, asynchronous network
interac-tions.In conjunction with other protocols, BEEP can
provide reliability, privacy, and authentication
op-tions Through transport mappings, BEEP specifies
how messages are carried over the underlying
trans-port mechanisms Profiles may be defined for BEEP
For example, the RAW profile is a backwardly
com-patible, efficient, readily implemented profile for
sup-porting legacy Syslog Protocol processing The
COOKED profile is intended for new
implementa-tions of Syslog Protocol handler, at the expense of
more overhead See RFC 3081, RFC 3195
beeper Colloquial term for a portable device that
alerts the user with an audible tone Commonly
in-corporated into pagers, a beep signifies that there is
a message awaiting the user, or some action to be
taken as a result of the alert signal
Beginning of Message BOM In ATM networking,
an indicator contained in the fIrst cell ofa segmented
packet The BOM segment is followed by
Continua-tion ofMessage (COM) and End ofMessage (EOM)
segments A header is associated with the segments
and they are passed to the Physical Layer for
trans-mission.Atwo-bit Segment Type (ST) field
identi-fies the type
Deilby layer Amicrocrystalline or amorphous layer
that is formed on the surface of metals by polishing
Being There 1 Aconsumer-priced, Macintosh-based
videoconferencing product from Intelligence at
Large, which provides video, audio, whiteboard, and
file sharing utilities over AppleTalk and TC/IP local
area and wide area networks 2 The title of a classic
Peter Sellers movie
belsymb -B.Aunit ofrelative power or strength of
a signal, which is not commonly used because it is
so large It is used in conjunction with amplitude,
usu-ally by its tenth measure, thedecibel. Named after
Alexander Graham Bell See decibel
Belden A major commercial manufacturer of com-munications media which has been responsible for influencing cable standards for many telecommuni-cations systems
bell 1.An audio device, often of resonant hollow metal, designed to emit sound when struck, vibrated
by a column of air, or vibrated through electrical stimulation 2 A digitally reproduced simulation of
a physical bell, created either by sampling a physical bell and playing back the sound, or by analyzing the type of sound wave patterns produced by a physical bell and simulating them mathematically Acomputer requires built-in electronics or a peripheral sound card
in order to send sounds to a speaker, especially if it's good quality 16-bit stereo sound Digital music syn-thesizers often have a wide array ofbell sound patches from which to choose 3 A phone bell that is acti-vated by line current from the switching office to in-dicate that there is an incoming call on the line Alexander Graham Bell- Inventor, Educator
Alexander Graham Bell continued to think ofhim-self as a teacher for the deaf long after he became famous andfinancially independent from sales ofhis technological inventions He and Helen Keller were friends Many ofthe members ofhisfamily were known
as excellent orators This portrait was photographed
by Moffett Studio when Bell was approximately 69 years ofage [National Archives ofCanada, Dept of External Affairs collection.}
Bell, AlexanderGraham (1847-1922) A Scottish-born American inventor, who was one of the origi-nal founders of the Natioorigi-nal Geographic Society He emigrated to Canada with his family and subse-quently found employment in Boston He studied aviation, electricity, fresh water distillation, etc., but
he is chiefly credited with the invention of the tele-phone.In fact, A Meucci had tested animal mem-branes as vibrational devices many years earlier and
a number of independent inventors in Europe and America were working on ways to transmit tones, and
in some cases voice, over telegraph lines Three sig-nificant contemporaries ofBell who achieved success
Trang 10Gray, and Thomas Edison.
In March 1876, two years after working out the
origi-nal concept, Bell and his assistant Watson reported
having transmitted Bell's spoken voice over
electri-cally charged wires, a story that caught the world's
imagination and ushered in the telephone age Bell's
patent was filed just hours before a caveat to file was
entered at the same office by Elisha Gray, for a
simi-lar harmonic telegraph Bell's talking phone was not
demonstrated publicly until some time later One
in-teresting historical note is that Bell's patent did not
mention the use ofa liquid medium, yet the
rudimen-tarytelephone that was later demonstrated did use a
liquid medium, a structural detail that was mentioned
in the Gray caveat
Model of the First Telephone
A model reconstruction ofwhat Bell has described
as theftrst telephone invented by him in1875,referred
to as the "Gallows Telephone" due to its shape
{Li-brary ofCongress Detroit Publishing Company
Col-lection Published ca 1920.J
There was significant critical interest in the invention
On31 Aug 1876, Anna Joy wrote to Bell, asking him
"Was an experiment tried at your office for
transmit-ting sound by Electricity? If so when was it tried?
Who were the parties engaged? What was the result?"
to which Bell gave an uncharacteristically cryptic
re-ply:
"~Sept.lst, 1876./TheManag.oftheP.&A
T Co has forw to me your note of the 31 st ult
and I beg to state tho expo were made with my app
for the tel transm of vol s under the direct of
Sir William Thompson at the office of the Pac &
At Tel Co - but at what date I am unable at the
pres mom to state / Yrs truly / A Graham Bell"
In April 1877, Bell acknowledged a request from
Boston professionals for a 'practical demonstration
ofmy Electric Telephone' and made arrangements to
publicly describe his invention three weeks later
Given all the hedging and the murmur ofcontroversy
over the veracity of the original claim, one wonders,
in retrospect, ifBell's famous message to Watson was
fabricated or exaggerated because the ambitious Bell
feeling he was on the verge of success
In 1880, Bell devised a means to transmit phone sig-nals through light, a forerunner to fiber optic com-munications that languished for almost 100 years
~~~~c~rr~i~~:~:~~ technology made the c o n c e p t Bell's Historic Telephone Invention
Alexander Graham Bell making a historic call by opening the New York to Chicago long-distance line
on18October1898.{National Archives of Canada image.J
A historic report in the Detroit News on 'BellsFirst Telephone ' {Library ofCongress Detroit Publishing Company Collection, ca 1920 Photo by Underwood
& Underwood, Inc.J
In 1882, Bell was granted United States citizenship though he continued to maintain a summer home in Nova Scotia, Canada
Bell achieved enormous financial success and could have ceased working at a young age, but he contin-ued to research aeronautic kites (he succeeded in get-ting a manned, motorized aircraft aloft in 1908), hy-drofoils, and various technologies to aid the deaf, most notably the audiometer For much of his life,
he listed his occupation as teacher of the deaf