Fiber Optics Illustrated Dictionary - Part 15 ppt

Fiber
Optics
Illustrated
Dictionary
Brewster's
Angle
Applied
to
Light
different
degrees,
depending
upon
the
angle,
with
Brewster's
angle
being
the
relationship
where
polar-
ization
is
at
its
maximum.
If
the
incident

light
is
al-
ready
polarized
in
a
direction
parallel
to
the
dielec-
tric
surface,
it
will
not
be
reflected.
There is a particular angle
at
which unpolarized
light, when encounteringa dielectric surface, reflects
as maximally polarized, called
Brewster's
angle,
ex-
pressed as
8
p

•
The angle
of
reflection, relative to the
dielectric surface normal, is complementary to the
angle
of
the refracted light, relative to normal. Con-
versely,
if
light that is already polarized (in a direc-
tion parallel to the surface plane) is incident to the
surface, thepolarizingeffect
of
the dielectric cancels
outthepolarizedincident light
and
nopolarizedlight
is reflected.
Brewster
sangle is consistent
for
incident light
and
dielectric materials with the samecharacteristics, but
varies with the wavelength
and
index
of
refraction

of
the dielectric with which the incident light interacts.
polarized
reflected
light
Ci
E
o
c
unpolarized
incident
light
Brewster's law
With
respect
to
electromagnetic
en-
ergy
encountering
a
dielectric
material,
the
relation-
ship
between
the
angle
of

propagation
of
the
reflected
energy
relative
to
the
perpendicular
of
the.
surface
(nonnal),
and
the
refractive
index
of
the
dielectric
ma-
terial,
can
be
described
in
an
equation
derived
by

Brewster,
known
as
Brewster slaw
sO,6
p
r·
4
•••
·
••
::·
•••
·.~}
•••
~·
••
il~fl8p
·PQ~f.ip.
In
this
equation,ep(ih~:~lli'gieai~hich
the
polariza-
tion
effect
for
the
reflected
energy

is
at
its
maximum
for
a
given
material
and
wavelength)
is
Brewster
s
angle.
The
index
of
refraction
of
the
dielectric
mate-
rial
is
expressed
as
n.
Thus,
the
refractive

index
is
equal
to
the
tangent
of
the
angle
of
the
reflected
en-
ergy
(relative
to
surface
normal).
This
information
is
useful
for
designing
components
that
are
intended
to
maximally

polarize
unpolarized
radiant
energy
or
to
not
reflect
already-polarized
energy
(polarized
par-
allel
to
the
surface
plane).
The
accompanying
dia-
grams
help
clarify
these
relationships.
Examples
of
applications
that
exploit

Brewster's
law
which
excessive
voltage
is
detected
and
the
circuit
tripped
or
broken
in
order
to
prevent
overload,
elec-
trical
fires
or
damage
to
appliances
or
the
main
panel.
2.

In
radio
communications,
anyone
who
drops
in
on
a
channel
to
communicate
when
others
are
already
engaged
in
conversation.
3.
In
public
online
forums,
a
person
who
breaks
into
an

ongoing
conversation
or
thread
with
irrelevant
or
unkind
and
unwanted
com-
ments.
breaking strength
1.
An
industrial
measure
of
the
force
needed
to
break
a
specific
structure
or
material
(or
a

combination
of
the
two).
Used
in
structural
and
safety
design
and
selection
and
installation
of
appro-
priate
wires
and
cables.
breakout
An
exit point
for
electrical conductors
(wires,
cables,
etc.)
along
the

length
of
the
circuit,
between
the
endpoints
of
the
circuit.
Breakouts
can
be
used
for
additional
installations
or
testing
and
di-
agnosis
of
the
circuit.
Breakouts
are
usually
covered
or

capped
in
some
way
to
prevent
interference
with
the
circuit
and
shock
or
fire
hazards.
breakout box A
diagnostic
instrument
used
to
tap
into
an
existing
circuit
to
evaluate
its
functioning,
to

see
whether
individual
lines
within
a
group
are
cor-
rectly
connected,
and,
in
some
cases,
to
detect
which
signals
are
being
transmitted.
Breakout
boxes
often
have
indicators
such
as
tones

or
light-emitting
diodes
(LEOs)
to
help
assess
the
line
and
may
include
jump-
ers
to
temporarily
switch
connections.
One
useful
application
of a
breakout
box
is
to
test
a
serial
cir-

cuit,
since
computer
equipment
manufacturers
don't
consistently
follow
the
RS-232
or
RS-423
specifica-
tions.
In
the
case
ofa
temporary
need
for
a
null
mo-
dem
cable
(e.g.,
for
transferring
information

from
one
computer
to
another
through
telecommunications
software),
a
breakout
box
can
be
used
to
cross
the
transmit
and
receive
lines.
See
breakout.
Brewster's angle
In
the
context
of
an
electromag-

netic
wave
encountering
a
dielectric
material,
there
is
a
particular
angle,
called
Brewster's
angle,
at
which
the
polarization
effect
of
the
interaction
is
at
a
maxi-
mum,
whether
this
is

the
polarization
and
reflection
of
unpolarized
radiant
energy
(e.g.,
white
light
from
the
Sun)
or
the
"cancellation" of
energy
through
ab-
sorption,
ifit
is
already
polarized
parallel
to
the
di-
electric

surface
before
contact.
Different
materials
refract
light
to
different
extents.
Much
of David Brewster's research centered
on
studying
the
different
optical
properties
of
crystals,
including
their
reflective
and
refractive
properties.
The
specific
angle
at

which
Brewsterian
effects
oc-
cur
was
found
to
be
related
to
the
refractive
index
of
the
dielectric
material
encountered
by
the
propagat-
ing
incident
wave
and
the
polarization
and
other

char-
acteristics
of
the
incident
radiant
wave.
Brewster's
angle
will
be
between
0°
-
90°
since
no
polarization
occurs
if
the
radiant
energy
hits
the
dielectric
at
an
angle
perpendicular

to
the
material
(0°
-
straight
on)
or
travels
parallel
to
the
dielectric's
contact
surface
(90
0
-
thus
not
being
reflected).
If
the
incident
light
is
unpolarized
when
it

encounters
the
dielectric,
the
reflected
light
will
be
polarized
to
132
© 2003 by CRC Press LLC
and
Brewster's
angle
include
photographic
filters,
sunglasses,
radio
signal
conditioners,
fiber
optic
cou-
plers,
photographic
films,
and
a

wide
variety
of
com-
ponents
for
scientific instruments
such
as
micro-
scopes.
Brewster's
law
has
broad
and
consistent
applications
in
optics
that
are
very
useful
but
may
sometimes
be
a
hindrance.

Novel
ways
to
overcome
some
of
its
ef-
fects
have
been
recently
developed.
In
the
1990s,
it
was
found
that
highly
birefringent,
layered,
polymer
film
could
be
assembled
in
alternating

layers
to
con-
trollight
so
that
the
net
effect
was
to
avoid
polariza-
tion
of
the
reflected light that
is
characterized
by
Brewster's
angle.
This
led
to
the
development
of
lay-
ered

film
components
capable
of
reflecting
light
uni-
formly,
which
has
many
potential applications
in
communications,
astronomy,
and
medical
imaging.
See
acceptance
angle,
blaze
angle,
Brewster's
angle,
dichroic,
incidence
angle,
Malus's
law,

Snell's
law.
Brewster,
David
(1781-1868)
Scottish-born
British
author,
qleric,
educator,
and
scientist
who
built
tele-
scopes
as
a
child
and
entered
university
as
a
young
adolescent.
Brewster
fulfilled
his
early

promise
and
demonstrated
talent
in
many
fields
of
endeavor.
He
was
admitted
to
the
Royal
Societies
of
Edinburgh
and
London
and
received
many
medals
and
honors
dur-
ing
his
lifetime.

He
served
as
editor of
the
Edinburgh
Encyclopedia
for
two
decades
and
as
president of
the
University
of
Edinburgh
for
almost
a
decade
near
the
end
of
his
life.
Much
of
Brewster

's
important
experimental
research
was
in
the
field
of
optics,
with
a
focus
on
the
struc-
tural
components
of
the
eye,
as
well
as
the
interac-
tion
of
light
with

the
optical properties of
crystals
which,
in
turn,
led
to
the
formulation
of
Brewster
s
law
to
describe properties related
to
polarization.
Around
1811-1813,
he
noted
that
there
was
a
particu-
lar
angle,
Brewster s

angle,
at
which
the
interaction
of
light
with
a
mineral
substance
has
a
maximal
ef-
fect
related
to
polarization.
Over
the
next
two
de-
cades,
he
extended
his
studies
into

the
spectral
char-
acteristic
of
glasses
and
gases
and
studied
fluores-
cence
in
chlorophyll.
Brewster balanced
his
experimental observations
with
his
talent
for
building
things.
He
invented
a
com-
pact
kaleidoscope
that

was
granted
a
patent
in
1817,
and
also
established
the
foundation
for
a
new
optical
lens
system
that
could
transmit
bright
light
suitable
for
lighthouses,
in1835.
See
Brewster's
angle.
BRI

See
Basic
Rate
Interface.
bridge
1.
A
link
that
provides
a
connection
across
a
physical
or
conceptual
gap.
This
link
mayor
may
not
be
intended
to
affect
the
quality
or

format
of
the
ob-
jects
or
information
crossing
the
gap.
2.
In
networks,
a
device
commonly
used
to
handle
communications
between
separate
local
area
networks
(LAN
s)
which
mayor
may

not
use
the
same
protocols.
Thus,
To-
ken-Ring
networks
and
Ethernet
networks
may
be
connected via a bridge.
In
Frame
Relays,
a
bridge
encapsulates
LAN
frames
and
feeds
them
to
a
Frame
Angles

ofIncidence, Reflection,
and
Refraction
polarized
reflected
light
"ii
E

o
c
~~
refracted
'"
light
'"
B
incident
light
Incident
light
A
This diagram shows the basic relationships between incident electromagnetic energy interacting with dielectric
materials with different properties. Imagine that thepropagating wave is white lightfrom the Sun traveling through
air (which is
itself
a dielectric) to encounter a solid dielectric material. Materials with different refractive indexes
(A
and
B) are

shownfor
comparison. The collision
of
the incidentlight with the surface
of
the dielectric
(a
material that
does not readily conduct energy) causes the direction
of
travel
and
polarity
of
the light to change. Depending upon
the properties
of
the dielectric solids,
some
of
the light will
be
reflected, some will
be
absorbed, and some will
continue
on
down through the dielectric
but
at

a different angle, called the angle
of
refraction.
In both
(A)
and
(B),
the angle
of
the incident light (the light hitting the suiface)
and
the reflected lightare the same
relative to the suiface normal (perpendicular to the suiface)
and
there is a direct relationship between the index
of
refraction and the direction
of
travel
of
the scatteredlight.
As
the refractive index
and
the angle
of
the incident light
increases, so does the angle
of
the reflected light, up to thepoint

at
which it is parallelto the surface (in which case
it doesn
~
reflect).
Depending upon theproperties
of
the reflective material, not allthe light willbe reflected. Some may be absorbed
and
some may
be
refracted through the material. The angle
of
refraction (light that
passes
through the material
ratherthan reflecting
off
of
it) is relatedto the angle
of
the incidentlight andits interaction with therefractive material.
133
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
Basic Categories
of

Network Bridges
bridge number
BN.
Aring network designator
used
in
source
routing.
Together a segment number
(SN)
and
bridge number
(BN)
comprise a route designa-
tor.
When
a destination
is
located
on
the
ring
itself,
the
bridge number
is
0 (zero).
Bridge Protocol Data Unit BPDU.InATM
network-
ing,

a
message
type
used
by
bridges
to
exchange
man-
agement
and
control information. BPDU
is
a Media
Access Control
(MAC)
management control proto-
col
used
to
implement
Spanning
Tree
Protocol
(STP).
It
provides a mechanism for routing data traffic
Relay switch
for
subsequent transmission.

It
also
re-
ceives frames
from
the network, strips the Frame
Relay
frame,
and
passes
the
LAN
frame
on
to
the
end
device.
Bridges
in
computer
networks
are
associated
with
the
Media Access Control
(MAC)
layer (or
in

OSI,
the
MAC
sublayer). Bridges
fall
somewhere between
repeaters
and
routers, although with increasing
tech-
nological sophistication the distinction between
bridges
and
routers
is
less
clear.
Bridges
can
be
clas-
sified
into
general categories.
See
brouter,
eXtranet,
Media
Access Control address,
repeater,

router,
spanning tree algorithm.
bridge, acoustic
In
acoustic instruments,
the
bridge
elevates
and
spaces
the
strings
and
transfers vibra-
tions
to
the
body
(soundbox)
of
the
instrument.
In
electronic
instruments,
the
bridge elevates
and
spaces
the

strings
and
transfers vibrations
to
the
body
of
the
instrument
where
they
are,
in
tum, converted
into
electrical signals, usually
by
an
energy-conversion
device called a
pickup.
Type
of
Bridge
transparent
source
routing
source
routing
transparent

Description
A
general
purpose
bridge
widely
used
on
Ethernet
networks
that
supports
multiple
bridges
in
a spanning
tree
configuration. Atransparent
bridge
builds
its
own
MAC
address
table
based
on
source
information
from

incoming
traffic.
Reference
IEEE
802.1.
Specific
to
Token-Ring
networks.
Routing
is
determined
at
the
source,
rather
than
at
the
bridge
and,
hence,
incoming
frames
contain
routing
information
and
an
indicator

as
to
whether
it
should
be
used.
Reference
IEEE
802.5.
A
less
common
hybrid
configuration
used
in
a
small
percentage of
implementations.
through
a
single
conduit
when
more
than
one
physical

conduit exists (e.g., a backup
loop
for
use if
the
root
loop
fails).
The
BPDU consists
of
flags, Hello
time,
and
root,
port, bridge, protocol, delay,
and
aging
in-
formation.
bridger switching A technique for improving
low
return
transmissions,
as
in
cable
networks,
by
sequen-

tially turning
on
and
off
each
leg
of
the distribution
circuit. It
is
sometimes
used
in
conjunction with
high
pass
filters. While improvements
in
reliability
can
be
attained
in
this
way,
it
is
at
the
cost

of
greater
com-
plexity
and,
hence, greater expense.
bridging clip Asmall piece
of
conducting apparatus
used
to
connect nearby terminals, contacts,
or
other
circuit elements that
are
close together, either
for
the
purpose
of
changing a circuit (usually temporarily)
or
for
testing
it.
Bright, Charles Tilson (1832-1888) An English
in-
ventor
and

chiefengineer
for
the
Magnetic
Telegraph
Company.
Bright
was
the
first
to
undertake under-
ground cable installation with gutta-percha
as
an
in-
sulating material.
When
Edison
was
installing
the
historic Washington-Baltimore line
in
the 1830s,
problems
with
insulation
and
ground-breaking caused

the
line
construction
to
be
changed
from
underground
to
overhead,
so
Bright's success with
an
underground
line
was
important. Later, Bright installed
the
first
cables
to
be
laid
in
deep
water, first with a shallower
line
across
the
English Channel

in
1851,
and
two
years
later adeepwater
line
between
England
and
Ire-
land.
Further lines around
the
world followed.
brightness The level of luminosity
or
amount of
il-
lumination emanating
from
a surface
or
display
me-
dium.
Luminance
is
used
to

describe
the
lightness
or
brightness component
of
a television broadcast sig-
nal. Brightness across the visible spectrum
is
not
equally perceived
for
different colors.
See
contrast.
Brillouin, Leon (1889-1969) AFrench-born Ameri-
can
quantum physicist
who
studied
band
structures
in
crystalline solids. Brillouin
is
best
known
for
de-
scribing Brillouin scattering, a quantum effect

in
acoustic
modes
in
refractive materials.
In
the
I920s, Brillouin
made
important discoveries
in
quantum dynamics, developing a means
of
ap-
proximating solutions
to
the Schrodinger equation.
He
accepted a position at
the
Sorbonne
in
the
late
1920s.
In
the
1930s,
he
was

associated
with
the
Born
Institute
in
Goettingen.
In
the
1940s,
he
took
posi-
tions
at
American universities
and
authored Wave
Propagation in Periodic Structures.
In
1948,
he
be-
came director
of
Electronic Education at IBM.
Brillouin
then
joined Columbia University
at

a time
when
exciting evolutionary advancements
in
lasers
were
being
made
by
scientists
such
as
C.
Townes.
See
Brillouin scattering.
The
Laboratoire
Leon
Brillouin
is
named
in
his
honor.
Brillouin scatteringAfrequency change/phase shift
effect that occurs
in
scattered light
from

compres-
sions/decompressions
in
an
elastic, refractive mate-
rial.
Thus, photons
are
interacting with vibrational
structures
at
the quantum
level
within
the
light-re-
fracting medium
as
opposed
to
simply encountering
134
© 2003 by CRC Press LLC
incongruities
within
the
structure
(Rayleigh
scattering).
Brillouin

scattering
occurs
when
the
light-refracting
structure
exhibits
transverse
and
pseudo-transverse
elastic
compressibility
(called
acoustic
modes
due
to
the
compression/decompression
character of
sound
waves
traveling
through
a
medium).
Brillouin
effects
are
complex

and
subtle
interactions
that
can
be
chal-
lenging
to
measure
and
that
depend
upon
many
fac-
tors,
including
density,
refractive
index,
elasticity,
temperature,
humidity,
vibrational
intensity,
the
di-
rection
of

the
incident
light,
etc.
Neverthless,
scien-
tists
are
endeavoring
to
characterize
and
harness
Brillouin
effects
for
use
in
fiber
optic
and
other
tech-
nologies.
This
effect
was
first
studied
by

Leon
Brillouin,
ca.
1920.
The
mathematics
of
the
scattering effect
was
not
well
understood
until
the
study
and
development
of
lasers
and
fiber
optics
in
the
early
1970s
gave
it
a

wider
context
in
which
to
be
researched.
This,
in
turn,
furthered
development
ofnonlinear
fiber
optics
and
the
understanding of other optical phenomena
and
modulation
technologies.
Brillouin
scattering
may
impose
limitations.
For
ex-
ample,
in

optical
fibers,
increasing
the
power of
the
light
in
a
cable
causes
it
to
reach
athreshold
at
which
point
Brillouin
effects
impose
physical
limitations
on
light propagation. Acoustic noise arising from
Brownian
molecular
motion
can
stimulate

spontane-
ous
Brillouin
scattering
causing
back
reflection.
Brillouin
scattering
is
a useful
tool
for
researching
molecular excitation
and
Brillouin effects
may
be
deliberately
stimulated
for
use
by
testing
and
correc-
tion
components.
The

effect
can
also
be
exploited
in
the
development
of fiber-based
sensors.
S.
Burgett
et
al.
have
described
the
use
ofBrillouin
optical
time
domain
reflectometry
to
carry
out
strain
measurments
in
precision-wound

optical
fibers
and
L.
Thevenaz
et
al.
have
described
strain
and
temperature
sensing
us-
ing
embedded
optical
fibers.
See
acoustical
Doppler
effect,
Bragg's
law,
Raman
scattering,
Rayleigh
scat-
tering,
Stoke's

shift.
British
Academy
of
Film
and
Television
Arts
BAFTA.
Established
by
Alexander
Korda
in
1946
as
a
club
for
the
British
film
elite,
the
club
evolved
into
the
British
Film

Academy,
founded
in
April
1947.
It
later
merged
with
the
Guild
of
Television
Producers
and
Directors
to
form
the
Society
of
Film
and
Tele-
vision
Arts.
BAFTAsupports
the
Film
Awards

as
well
as
Television and Children's
Awards
programs.
/>BritishApprovals Boardfor Telecommunications
BABT.
A
U.K based
telecommunications
regulatory
organization,
the
BABT
provides third-party
accred-
ited
regulatory
and
certification
services.
BABT
Cer-
tification
marks
are
commonly
recognized
in

Europe.
In
AprU
2001,
the
BABT
announced
its
affiliation
with
TUV
SiiddeutschlandAG.
The
merger
resulted,
in
part,
in
the
creation
of
BABT
Product Service
USA,
which
focuses
on
telecommunications
confor-
mity

assessment.
BABT
Product
Service
also
has
centers
in
several
Asian
countries.
http://www.
babt.co.
uk!
BritishBroadcasting Corporation
BBC.
A
television
broadcast provider
since
the
late
1920s,
when
it
be-
gan
its
fITst
experimental

television
transmissions,
the
BBC
began widespread public broadcasting
from
London
in
1936.
British
Computer
Society
See
computer
societies,
national.
British Film Institute BFI
An
independent
Royal
Charter
body,
founded
in
1933,
that
promotes
under-
standing
of

the
moving
image
arts,
including
televi-
sion
and
film.
It
fulfils
the
cultural
and
educational
roles
of
the
Film
Council.
!
BritishIndian SubmarineTelegraph CompanyAn
underwater
telegraph
cable-laying
company
founded
by
John
Pender,

aBritish
merchant,
in
1869,
not
long
after
the
laying
of
the
first
oceanic
telegraph
cable
traversing
the
Atlantic
Ocean.
Through
his
involve-
ment
with
the
transatlantic
cable
project,
Pender
was

inspired
to
propose
a
cable
connection
between
Brit-
ain
and
India,
where
the
British
had
established
large
centers
of
trade
and
colonization.
In
1872,
he
also
es-
tablished
the
Eastern

Telegraph
Company.
Within
a
decade,
the
company
supported a
majority
of
tele-
graph
traffic
to
India
and
had
expanded
to
include
Australia,
China,
and
Japan
through overland
and
underwater
cables.
Eventually Pender
achieved

his
ambitious dream when London, England and
Bombay,
India
were
linked in
1879.
BritishNationalCorpus
BNC.
A
very
large
linguis-
tic
collection
of
written
and
spoken
British
English
compiled
from
1991
to
1994
under
the
management
of

an
academic/industrial consortium
led
by
Oxford
University
Press.
In
terms
of
technology,
the
collec-
tion
is
ofinterest
in
the
fields
of
speech
recognition
and
synthesis
(telephony,
computer
text
dictation
and
generation,

etc.)
and
artificial
intelligence
(especially
natural language synthesis
and
processing).
BNC
Online
is
hosted by
the
British
Library
Initiatives
for
Access
Programme.
The
BNC
is
licensed
material,
but
its
associated
SARA
Client
is

freely
available,
as
is
limited
demo
access
to
the
database.
British StandardsInstitution
BSi,
BSI.
A
U.K.
stan-
dards
body
which
provides
input
to
various
interna-
tional
standards
associations,
including
ISO
and

ITU-
T.
It
originated
as
a
Committee
within
the
Council
of
the
Institute of
Civil
Engineers
in
1901,
appointed
to
consider standardization
in
the
steel
industry.
The
Committee
of
engineers
and
naval architects

was
joined
by
the
Institute
of
Electrical
Engineers
in
1902.
In
1918,
it
became
the
British
Engineering
Standards
Association,
granted a
Royal
Charter
in
1929.
The
current
name
was
adopted
in

1931.
BSI
currently
sup-
ports about 19,000 live standards. It owns the
Kitemark
quality
mark.
/>British Telecom
BT,
British Telecommunications
pIc.
Originally affiliated with
the
British
Ministry
of
Defence
and
British Post
Office,
the
telephone
net-
work
and
telephony
research
arms
separated

from
the
Post
Office
to
become
British
Telecom.
BT
publishes
the
quarterly BT
Technology
Journal
(technical
pa-
pers)
and
sphere
(BT
technology) with
copies
avail-
able
on
the
Web.
135
© 2003 by CRC Press LLC
Fiber

Optics
Illustrated
Dictionary
BritishTelecom Research Laboratories
BTRL.
The
research
lab
ofBritain's
largest
telecommunications
provider,
based
in
Marlesham
Heath,
Suffolk,
En-
gland.
British
Telecom
is
involved
in
many
interna-
tional
collaborative
projects
including

research
with
the
Massachusetts
Institute of
Technology
in
artifi-
cial
intelligence
natural
language
processing.
British thermal unit
Btu.
The
unit
ofthennal
energy
required
to
raise
the
temperature
of 1
pound
of
liq-
uid water
by

1
degree
Fahrenheit
at
sea
level.
1
Btu
=
251.996
calories
=
1054.8
Joules.
Optical
sensors
have
been
developed
to
measure
Btu's.
While
gener-
ally
used
to
express
the
energy-producing

or
trans-
ferring
capability
ofheating/cooling
systems,
it
is
also
used
to
express
the
heat
generated
by
large-scale
com-
puting
systems
to
facilitate
the
design
of
building
cir-
culation
systems
associated

with
their
installation.
brittleA
quality
ofa
physical
substance
lacking
elas-
ticity,
one
that
is
vulnerable
to
breakage.
Substances
may
be
brittle
in
one
set
of
circumstances
and
not
another,
e.g.,

electrical
components
or
connectors
may
be
vulnerable
below
or
above
certain
operating
temperatures.
broadband A
band
of
frequencies
wide
enough
to
be
split
into
narrower
bands,
each
capable
of
indi-
vidual

use
for
a
variety
of
transmissions
or
for
trans-
missions
by
a
variety
of
users.
Broadband
transmis-
sion
requires
suitable
hardware
and
cabling,
capable
of
quickly
transmitting
and
receiving
a

large
amount
of
infonnation.
Fiber
optics
are
often
used.
The
en-
tire
breadth
of
the
band
is
not
necessarily
used
for
transmissions,
depending
upon
supply
and
demand.
Also,
there
may

be
gaps
between
bands
to
prevent
interference.
Cable
TV
is
a ubiquitous
example
of
broadband
transmissions
where
the
band
is
split
into
all
the
different
channels
to
which
the
recipients
have

subscribed.
As
in
many
broadcast
media,
broadcast
technologies
tend
to
be
one-way,
or
mostly
one-way,
but
with
the
increased
demand
for
interactivity,
more
two-way
communications
over
broadband
are
being
developed.

See
baseband,
telecomputer,
wideband.
Broadband
Connection-Oriented
Bearer
See
BCOB.
broadbanddigital cross-connectsystem
B-DCS.
A
digital
cross-connect
system
that
accepts
a
variety
of
optical
signals
and
is
used
to
tenninate
SONET
and
DS-3

signals.
B-DCS
accesses STS-l signals
and
switches
at
this
level
and
is
appropriately
used
as
a
SONET
hub
for
routing
and
other
functions.
B-DCS
is
commonly
implemented
with
node
tennination
via
add/drop

multiplexers
(ADMs)
and
B-DC
switches.
Some
newer
optical
systems
that
provide
SONET-like
capability
can
transmit
without
the
B-
DC
switches.
See
wideband
digital
cross-connect
system.
Broadband High
Layer
Information
BHLI.
An

ATM
infonnation
element
that
uniquely
identifies
an
application
(or
session
layer
protocol
of
an
applica-
tion).
BHLI
is
implemented
in
various
ways,
depend-
ing
upon
whether
the
codepoint
is
user-specific,

ven-
dor-specific,
or
ISO.
broadband integrated gateway
BIG.
A
component
ofHFC
(Hybrid
Fiber
Coax)
networks
that
converts
136
an
ATM
transmission
into
a
signal
that
can
be
trans-
mitted
over
the
HFC.

Working
in
conjunction
with
a
connection
management
controller
(CMC),
the
BIG
strips
infonnation
from
ATM
cells
and
orders
and
addresses
them
for
further
transmission.
See
connec-
tion
management
controller,
HFC.

Broadband ISDN
See
B-ISDN.
Broadband Lightwave Sources
and
System
See
BLISS.
broadband line termination
B-LT.
Optical
or
elec-
tricalline tennination
(LT)
on
a
broadband
network
that
provides
a
physical
and
link
between
an
access
network
and

a
local
digital
exchange.
The
tennina-
tion
unit
will
convert
signals
as
needed
and,
in
some
cases,
provide multiplexing
functions
for
multiple
attached
devices.
Broadband
Passive
Optical
Network
BPON,
Broadband paN. An optical communications
net-

work
capable
ofproviding
high
bandwidth
services.
Commercial
implementations
of
consumer
program-
ming
via
BPON
provide
a
range
of
up
to
about
20
kilometers
on
a
single
fiber
serving
a
couple

of
dozen
or
more
customers.
Broadband
Telecommunications
Architecture
BTA.
An architecture introduced
by
General
Instru-
ment
for
multimedia
networking.
broadband terminal
adapter
BTA.
A
data
commu-
nications
device
that
interfaces
a
broadband
ISDN

(B-
ISON)
connection
to
other
terminal
equipment
that
is
not
directly
compatible
with
B-ISDN.
broadbandtransport manager
BTM.
In
telephony,
atransport
mechanism
for
long-distance
portions
of
a
connection.
In
the
late
1990s,

Tellabs,
Inc.,
planned
field
trials
ofa
BTM
for
ATM
networks.
BROADBANDLOOP
BBL.
An
ACTS
project
for
defming
and
testing a concept
for
a cost-effective
broadband
access
network
allowing
fiber
to
be
inte-
grated

into
local
loops
as
telecommunications
band-
width
demand
increases.
The
target
user
base
for
the
project
is
residential
subscribers
and
small-
and
me-
dium-sized businesses. Field trials
were
set
up
for
Denmark,
Poland,

and
Portugal
with
some
trials
con-
sisting
of
overlays
to
existing
telephony
and
CATV
networks.
See
BLISS,
UPGRADE,
WOTAN.
broadcast
v.
To
transmit
sound,
images,
or
data
over
distance,
in

the
context
of
more-or-Iess
simultaneous
receipt
by
alarger
audience.
Transmission
can
occur
through
a variety of
media,
over
airwaves,
satellite
links,
wire
or
fiber,
or
a
combination
of
these.
Re-
ception
can

often
be
enhanced
with
antenna,
cable,
or
satellite
hookups.
Radio,
television,
and
Internet
chat
channels
are
common
broadcast
channels.
Commercial
and
high
power broadcasting
is
regu-
lated.
In
the
United
States,

the
Federal
Communica-
tions
Commission
(FCC)
is
the
primary
regulatory
body
and
has
jurisdiction
over
the
allocation
of
broad-
cast
frequencies.
In
Canada,
the
Canadian
Radio
Tele-
vision
and
Telecommunications

Commission
(CRTC)
handles
many
of
the
same
functions.
In
most
of
North
America,
very
low
power
broadcast-
ing
is
permitted without a license; otherwise
it
wouldn't
be
possible for people
to
use cordless
© 2003 by CRC Press LLC
phones,
baby
monitors,

and
wireless
intercoms
with-
out
being
licensed.
Generally
these
low
power
broad-
casts
are
limited
to
a signal strength of
250
micro-
volts
per
meter,
as
measured
three
meters
from
the
transmitter
for

FM
transmissions,
and
0.1
watts
on
a
maximum
three
meter
antenna
for
AM
transmissions.
This
effectively
limits
the
broadcast distance
to
100
feet
or
so
for
FM
and
a
couple
of

blocks
for
AM.
Tra-
ditional
broadcasts
are
typically
in
the
range
of
535
to
1605
kHz.
Commercial
entertainment broadcasts
are
often fi-
nanced
by
revenues
from
sponsors
which
are
aired
in
the

fonn
of
commercials.
Since
this
revenue
model
has
been
successful
for
quite
some
time
in
the
televi-
sion
and
radio
industries,
it
is
not
surprising
that
many
broadcasters
are
turning

to
the
same
ideas
in
design-
ing
infonnation
to
be
viewed
over
the
Web.
In
con-
trast
to
commercial
stations,
however,
the
Web
is
far
less
regulated
and
has
many

more
participants,
and
it
will
be
interesting
to
see
how
Webcasting
evolves
over
the
next
several years.
See
television, radio,
multicast,
narrowcast,
unicast.
Broadcastand Unknown Server
BUS.
InATM
net-
works,
this
server handles
data
sent

by
an
LE
client
to
the
broadcast
Media
Access
Control
(MAC)
ad-
dress,
all
multicast traffic,
and
initial unicast
frames
which
are
sent
by
a
LAN
Emulation
(LANE)
client.!t
encompasses
the
functions

that
support
establishment
ofa
virtual
circuit
(VC)
connection.
See
Media
Ac-
cess
Control
address.
broadcastdatatrigger
Additional
services
are
some-
times
delivered
with
audio/video
broadcast
program-
ming.
Closed
captioning
or
subtitles

are
examples
of
traditional broadcast services
and
others
are
becom-
ing
available
as
digital broadcasting over computer
networks
increases.
Depending
on
the
medium,
cer-
tain
standardized broadcast triggers
have
been
de-
fined
and
categorized,
including transport
type
A

and
B
triggers.
Broadcast
triggers
are
realtime
data
events
associated
with
enhanced
TV
broadcasting delivered
in
a
textual
syntax
based
on
the
EIA
-
746A
standard
presented
through
the
ISO-8859-1
character

set
(U.S.
ASCII
or
Latin-I).
By
adding triggers
to
the
data
stream,
the
viewing
box
or
software
program
receives
a
signal
to
interpret
and
present
the
additional infor-
mation
or
services.
In

recent
years,
attributes
have
been
added
to
the
triggers
to
accommodate
Internet
broadcasts;
these
generally
require
two-way
commu-
nications.
The
presence of
two-way
communications
makes
it
possible
to
incorporate triggers
as
part of

an
on-demand
interactive
TV
system.
The
ATVEF
has
defined
two
modes
of
data
transport
that
incorporate
triggers.
Transport
A delivers
trig-
gers
by
the
forward
path
and
pulls
data
by
the

return
path.
Transport
B delivers triggers
and
data
by
the
forward
path,
but
the
return path
is
optional.
See
ATVEF
Enhanced
Content Specification.
broadcast list
1.
On
computer
networks,
a list of
us-
ers
to
whom
broadcast messages

are
sent,
usually
by
a
system
operator (sysop)
or
other
privi
leged
admin-
istrator.
See
broadcast
message.
2.
On
fax
machines,
alistof
recipients
to
whom
the
same
fax
will
be
sent.

broadcast medium
In
general,
the
physical
substrate
or
underlying
electromagnetic
phenomenon
that
pro-
vides
a conduit
for
electrical
or
other
signals
trans-
missions.
Electromagnetic phenomena
are
the
most
common
broadcast
media,
though
a

disturbance
in
a
medium (metal, water, wood, etc.) that produces
sound
waves
can
also
constitute abroadcast
medium
(albeit
slower
and
less
effective
than
electromagnetic
media).
In
some
networks,
a physical
layer
capable
of
supporting broadcast
messages.
broadcast message
1.
Amessage

sent
to
a selected
group
ofusers (or
all
users)
on
a
computer
or
radio
network. A
common
computer network broadcast
message
infonns
users
that
the
system
will
shut
down
in
5
or
10
minutes.
This

message
allows
users
to
save
work,
close
files,
and
finish
up
before
being
logged
out.
On
networks, broadcast functions
are
usually
available
only
to
those
with system privileges,
as
it
is
a capability
that
is

easily
abused.
Schools
are
be-
ginning
to
use
broadcast phone
or
email
messages
to
infonn parents
of
registration, reporting,
or
meeting
events
with
respect
to
their school-aged
children.
See
allcall,
anycall,
broadcast
list.
2.

A
message
broad-
cast
over
apublic broadcast
medium,
such
as
a
news
flash
or
Emergency Alert System
(EAS)
message.
3.
A
message
broadcast over a paging
or
public
ad-
dress
(PA)
system.
broadcast over network
In
ATM
networking,

data
transmissions
to
all
addresses
or
functions
on
the
sys-
tem.
Broadcast Pioneers
Library
An
education
and
re-
search resource located
in
the
Hornbake
Library
at
the
University
of
Maryland,
College
Park,
founded

in
1972.
The
collection includes correspondence,
books,
film,
video,
periodicals, historic
photographs,
scripts,
and
transcripts.
More
infonnation
is
available
online through the Pioneers'
Web
site.
/>broadcast standards Established
in
the
late
1930s
in
the
U.S.,
professional standards still
exist
as

im-
portant guidelines
for
ethical business practices,
safety standards,
and
standardized broadcast
formats
in
the
broadcast
industry.
See
Canadian Broadcast
Standards
Council, Federal
Communications
Com-
mission.
broadcast storm A broadcasting clamor
that
is
ex-
cessively
busy,
frequent,
or
powerful
that
it

overrides
other communications.
In
radio broadcasts, a
broad-
cast
storms
occur
in
times
of
emergency,
when
nu-
merous
operators simultaneously try
to
call
for
help
or
send
messages
to
friends
and
relatives. In
end-to-
end
systems,

such
as
analog wireline
telephone
sys-
tems,
broadcast
storms
as
such
don't
occur
(except,
perhaps,
in
adifferent
sense,
on
aparty
line),
because
excessive calling
will
result
in
a
fast
busy
being
sent

to
the
caller, indicating that
no
trunks
are
available,
rather
than
in
many
people talking
at
once.
In
data
networks,
however,
abroadcast stonn
can
occur
as
a
fault
condition
in
which
some
process
goes

wild
and
starts broadcasting
to
all
workstations
and
disrupting
user
interactions
and
work.
Astonn
may
occasionally
be caused on unsecured networks by a virus
137
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
distributed
by
a
vandal.
See
allcall, broadcast
mes-
sage.

Broadcast
Wave
Format
See
EBU
Broadcast
Wave
Format.
broadcasting satellite service
BSS.
One
of
two
di-
visions
into
which
Ku-band
satellite broadcast
ser-
vices
have
been
split.
BSS
operates
in
the
12.2-
to

12.7-GHz
range.
The
other
is
fixed
satellite service
(FSS).
See
ANIK,
Ku-band.
broadside array antenna Aphased array
(with
har-
nesses)
of
antennas
with
the
maximum
radiation
di-
rected perpendicularly
to
the
plane that holds
the
driven
elements.
This

antenna arrangement
can
be
configured
as
abillboard
antenna
by
adding
a
reflect-
ing
sheet
behind
the
array.
See
billboard
antenna.
Broadway
The
internal
development
code
name
for
The
X
Window
System

11
Release
6.3
(XIIR6.3)
from
The
Open
Group.
See
X
Window
System
11
Release
6.3.
Brocade Fabric
Aware
program
BFA.
A
testing
and
configuration
initiative
for
fostering
end-to-end
inter-
operability
for

storage
area
networks
(SANs)
in
multi-
vendor,
heterogenous environments. Participating
firms
agree
to
specify,
test,
and
support
pretested
SAN
configurations
with
a
mix
of
servers,
switches,
and
storage
subsystems.
Brocade
Fabric
Aware

qualifi-
cations
may
be
presented after
the
completion
of
rig-
orous testing
for
interoperability within specified
multivendor configurations. Brocade
Communica-
tions
Systems,
Inc.,
has
set
up
an
interoperability
laboratory
testing
environment
to
support
the
Fabric
Aware

program.
bronze An
alloy
consisting primarily ofcopper
with
tin
and
occasionally other
elements
added.
Brooks'
law
Adding
manpower
to
a late software
project
makes
it
later.
From
Frederick
P.
Brooks,
au-
thor of
The
Mythical
Man-Month,
a much-quoted

provocative
book
about
the
engineering
development
culture.
brouter, b-router
bridge
router.
Combination
de-
vices that
function
as
links between different
net-
works.
The
combination
ofa
bridge
and
arouter
pro-
vides
the
physical
and
logical connections

between
networks,
which
mayor
may
not
have
different
pro-
tocols,
and
routing
tables
to
facilitate
the
efficient
transmission
of
information
to
the
desired
destination.
A brouter
typically
performs
its
functions
based

on
information
in
the
data
link
layer
(bridging)
and
the
network
layer
(routing).
See
bridge,
router.
Brown
& Sharpe
Wire
Gauge
See
American
Wire
Gauge.
Brownian
movement,
Brownian
motion
Botanist
R.

Brown
observed
in
early
1827
that
pollen
grains
suspended
in
water
were
in
a
continual
state
of
agi-
tated
motion.
This
motion
has
been
widely
observed
for
small
particles
suspended

in
fluids.
It
is
said
that
the
molecules
of
the
suspension
medium
continually
buffet
the
particles, resulting
in
the
characteristic
movement.
Einstein
later provided a mathematical
explanation
of
Brownian
motion.
Theoretical
mod-
els
for

queueing
and
aggregated connectionless
net-
work
traffic,
based
on
fractional
Brownian
motion,
138
have
been
proposed.
brownout
1.
When
power
is
partially,
but
not
com-
pletely
lost.
Some
companies
use
an

industry-specific
definition
for
a
brownout,
usually based
on
arelative
or
specific
drop
in
voltage.
Complete
loss
of
power
is
called ablackout.
2.
In
cellular systems, asecurity
precaution used by some companies
to
prevent
fraudulent
use.
When
brownout
is

in
effect,
there
may
be
roaming
areas
in
which
asubscriber's
system
will
not
function.
browser
1.
An object-oriented
software
development
tool
for
inspecting a class
hierarchy.
2.
A software
utility
for
displaying
and
traversing

files
and
direc-
tories.
3.
A
software
client
for
accessing
the
resources
of
the
World
Wide
Web.
See
browser,
Web.
browser,
Web
A historic milestone
in
software
ap-
plications, designed
to
make
it

easy
to
access
World
Wide
Web
client/server resources stored
on
avariety
of
computers
on
the
Internet. Prior
to
the
develop-
ment of
Web
browsers, there were many publicly
available
and
valuable
data
repositories
on
the
Inter-
net,
but access

was
through inscrutable
line
com-
mands
or
uninspiring
textual
menus.
The
repositories
themselves
sometimes
included
images,
but
the
im-
ages
were
seldom directly viewable over a remote
link.
They
had
to
be
copied
and
then
loaded

into
a
compatible application supporting
the
various
for-
mats
in
order
to
be
useful
on
the
local
machine.
Web
browsers
simplified
this
process
by
providing
a 'front
end'
that
transparently automated, integrated,
and
standardized
access

to
the
more
sought-after
types
of
information stored
for
distribution
on
the
Internet.
The
Web
browser client/server
model
was
originally
developed
for
NeXTStep
by
Time
Berners-Lee,
in
1989.
As
the
concept
spread

through
various
systems
and
became
associated
with
the
Internet, another
im-
portant
change
was
taking
place,
the
commercializa-
tion
of
the
Internet
from
a research system
to
a
sys-
tem
that
could
be

used
for
commerce;
this
develop-
ment
got
the
attention
of
the
general public, even
those
with
no
previous interest
in
computers.
Avariety of
Web
browsers
were
quickly developed
to
meet
the
growing
demand
for
Web

access
from
different
types
of
computers,
resulting
in
phenomenal
growth
and
interest
over
the
next
decade
and
beyond.
Within
a
few
years
NCSA
Mosaic,
OmniWeb,
Lynx
(text
browser),
AWeb
(Amiga

Web),
Netscape Navi-
gator,
and
Internet Explorer had become popular
browsers
for
'surfing'
the
Web.
The
Web
gained
in
commercial
prominence
in
the
early
1990s,
and
browsers
developed
into
practical
tools
for
accessing,
traversing,
and

displaying
files
on
the
Internet. A browser interprets standardized
HTML
tags
that
are
used
to
describe
the
Web
page,
and
displays
the
results
on
the
user's
system.
Sun
Microsystems Java
applets
are
used
by
many

devel-
opers
to
further
enhance
the
capabilities ofabrowser
with
programming
algorithms
that
aren't
directly
sup-
ported
by
HTML
tag
interpretation.
Browsers
typically
download
HTML
pages
onto
the
local
drive,
so
they

can
be
more
quickly
redisplayed
when
the
user
moves
back
through
previously
viewed
© 2003 by CRC Press LLC
pages, and further facilitate
the
transfer
of
files
through
File
Transfer
Protocol
(FTP)
and
other
ex-
ternal utilities.
Some
browsers incorporate email

functionality
as
well
or
will
launch
the
email
utility
of
choice
when
an
email
anchor
is
selected
on
a
Web
page.
Most
browsers
supportplugins,
browser-com-
pliant
applications
for
processing
multimedia

file
for-
mats
from
a
variety
of
vendors.
Plugins
are
popular
for
enabling
the
user
to
play
music,
movies,
stream-
ing
video
news
broadcasts,
and
other
television-like
fonns
ofinfonnation
and

entertainment.
A
Web
browser's
simple,
accessible
means
ofmak-
ing
available
infonnation
on
the
Internet
has
resulted
in
an
explosion
ofinterest
and
participation,
increas-
ing
from
a
handful
of
users
in

1989,
to
more
than
30
million
in
1998.
The
number
of
data respositories
available
on
the
Internet
has
grown
in
conjunction
with
the
increase
in
users.
One
of
the
issues
that

becomes
more
important,
as
Internet
commerce
grows
and
data
repositories
in-
clude
more
and
more
personal
information,
is
secu-
rity.
Security enhancements
have
been gradually
added
to
Web
browsers
since
the
mid-1990s,

but
these
are
not
impervious
to
skilled
hackers.
Web
browsers
were
originally
designed
to
be
open
and
easy
to
use,
and
no
one
fully
anticipated
how
quickly
and
aggres-
sively

banks,
stores,
and
other institutions of
com-
merce
would
set
up
their
entire
service
line
and
cus-
tomer
access
databases
to
be
Web-accessible.
As
Web
browsers
become
more
powerful,
they
become
more

and
more
like
operating
systems
that
can
be
poten-
tially
accessed
and
controlled
from
remote
sources
in
sophisticated
ways.
Already,
by
1999,
there
were
companies
using
their
Web
browsers
to

'look'
at
in-
fonnation
on
the
desktop
of
the
individuals
who
in-
stalled
the
browsers
on
their
computers.
The
compa-
nies
didn't necessarily
inform
the
user of
this
intru-
sion,
or
did

so
in
small
print
or
vague
ways
not
un-
derstood
by
those
not
technically acquainted
with
computers.
If
computers
are
to
be
secure
in
the
future,
it
is
im-
portant
for

the
community
at
large
to
understand
the
potential
for
abuse
and
hold
companies
to
high
ethi-
cal
standards
in
the
matter
of
computer
and
individual
privacy
associated
with
Web
browsers.

Unfortunately,
many
people
don't understand
the
technical
or
po-
litical
issues
and
others
don't consider
the
long-tenn
consequences.
While
they
may
not
be
willing
to
give
out
name
and
address
information
on

a
moment-to-
moment
basis,
they
can
often
be
persuaded
to
do
so
when
offered
the
possibility of
winning
million
dol-
lar
sweepstakes.
Once
their
personal
information
gets
into
an
unethical
Web

respository,
it
can
be
redistrib-
uted
to
millions
ofother
computers
within
seconds;
there's
currently
no
way
to
undo
this
type
of
infor-
mation
theft,
which
may
include
social
security
num-

ber,
credit
card
numbers,
and
more.
Think
twice
be-
fore
volunteering
information
to
unfamiliar
Web
sites
through
your
Web
browser.
Another
security-related browser
issue
is
the
use
of
cookies,
identifiers within a browser that
enable

a
Web
site
to
recognize
automatically areturning user
without
querying
that
person
about
his
or
her
iden-
tity a
second
time.
Users
should
take
time
to
under-
stand
what
cookies
are,
how
they

work,
and
whether
they
should
be
explicitly turned off
in
the
browser
to
help safeguard privacy. Always read
the
privacy
policy statements associated with
each
site
before
providing
personal
information
and
boycott
sites
that
require
more
information
than
you

feel
they
need
to
carry
out
a transaction.
Web
browsers
have
opened
up
aworld of
communi-
cation, education,
and
opportunity
for
millions
of
people
and
will
likely
be
an
essential
aspect
of
the

Internet
for
a
long
time
to
come.
Many
Web
brows-
ers
are
freely
available
for
download
and
Netscape
Navigator
is
open
source
software
that
can
be
down-
loaded
and
modified

by
developers.
See
FTP,
Java,
HTML,
HTTP,
Internet,
NCSA
Mosaic,
PDA
mac-
robrowser,
PDA
microbrowser,
SGML,
World
Wide
Web.
browsing Searchingor
scanning
through
data
for
in-
formation
or
to
get
a general

feel
for
the
format
or
contents
of
a
body
of
information.
The
information
may
take
a variety of
forms:
text,
files,
directories,
images,
sounds,
etc.
See
browser.
brush A
conducting
structure
that
provides

an
elec-
trical connection between a motor and
its
power
source.
brute
force
1.
A problem-solving
method
that
in-
volves
trying
every
possible
combination
and
permu-
tation.
This
method
is
only
practical
for
small
prob-
lems

of
limited
scope
and
is
usually unwieldy
for
larger
or
more
complex
problems.
Sometimes
it
is
used
in
conjunction
with
other
problem-solving
meth-
ods
such
as
heuristics.
2.
A
programming
approach

that
involves
reliance
on
a system's
basic
capabili-
ties
and
processing
power,
rather
than
on
efficient
algorithms
and
elegance of design
and
concept.
A
brute
force
application
generally
does
not
run
quickly
on

legacy
systems.
brute
force attack An attack
on
a
security
system
using
every
possible
combination,
password,
login
name,
or
other entry
data
rather
than
using
atargeted
strategy.
Brute
force
attack
data
are
often
generated

automatically with
computer
software.
This
type
of
attack
is
usually easily detected
and
is
often
not
very
effective.
BS
1.
See
backscatter.
2.
band
signaling.
3.
See
base
station.
4.
See
beam
splitter.

BSAM
See
basic
sequential
access
method.
BSCC
BellSouth
Cellular
Corporation.
A
corporation
serving about
10%
of
the U.s. wireless market,
formed
in
1991.
BSD
See
Berkeley
Software
Distribution.
BSE
1.
back-scattered electrons.
2.
Basic
Service

Element.
3.
Basic Switching Element.
In
packet
switched
networking,
a
basic
unit
which
may
be
com-
bined
with
other
BSEs
to
emulate
alarger
switching
topology.
BSF bit scan forward.
An
assembly language bit
manipulation
in
which
a bit string

is
searched
for
a
set
or
cleared
bit,
from
low-order
to
high-order.
See
BSR.
139
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
BSFT
See
Byte
Stream
File
Transfer.
BSI
See
British
Standards

Institution.
BSL
See
British
Sign
Language.
BSMS
1.
billing
and
subscriber
maintenance
service.
2.
Broadcast
Short
Message
Service.
BSMTP
See
Batch
Simple
Mail
Transfer
Protocol.
BSP
1.
Bell
System
Practice.

Bell
internal
policies
and
procedures
for
creating
instructional
manuals
for
the
servicing,
support,
and
operation
of
phone
equip-
ment.
2.
See
byte-stream
protocol.
BSR
1.
bit
scan
rate.
2.
bit

scan
reverse.
An
assem-
bly
language
bit
manipulation
in
which
a
bit
string
is
searched
for
a
set
or
cleared
bit,
from
high-order
to
low-order.
See
BSF.
BSS
1.
Base

Station
System.
2.
See
broadcasting
sat-
ellite
service.
2.
Business
Support
System.
BSVC
1.
Broadcast
Switched
Virtual
Connections.
2.
The
name
for
an
object-oriented,
generic
micro-
processor
simulation
framework
for

building
a
vir-
tual
computer
that
evolved
from
a
Motorola
68000
simulator
supporting
the
6850
UART.
BT
1.
See
British
Telecom.
2.
Burst
Tolerance.
In
asynchronous
transmissions
mode
(ATM)
connec-

tions
supporting
variable
bit
rate
(VBR)
services,
BT
is
the
limit
parameter
of
the
GCRA.
See
cell
rate.
BTcutcrystalA
type
of
crystal
with
vibratory
quali-
ties
that
makes
it
suitable

for
crystal
radios.
BTPhonebaseA
service
of
British
Telecom
since
the
early
1990s
that
enables
subscribers
to
make
direc-
tory
enquiries
through
a
computer
modem.
The
da-
tabase
is
updated
continuously

and
is
more
up-to-date
than
a
yearly
paper-based
telephone
directory.
The
call
is
billed
at
long-distance
phone
rates
but
is
gen-
erally still
less
expensive
than
Directory
Enquiry
(U
.K.
Directory

Assistance
service).
The
typical
con-
nect
speed
is
2400
baud,
though
higher
rates
became
available
in
some
areas
as
of
1999.
See
TeleDirectory.
BTA
1.
See
Basic
Trading
Area.
2.

See
Broadband
Telecommunications
Architecture.
3.
See
broadband
terminal
adaptor.
BTag
Beginning
Tag.
In
ATM,
a
one-octet
field
of
the
CPCS_PDU
used
in
conjunction
with
the
Etag
octet
to
fonn
an

association
between
the
beginning
ofa
message
and
end
ofa
message.
BTBT band-to-band tunneling. Direct transfer of
electrons
from
filled
valence
band
(VB)
states
to
empty
states
or
recombination
of
electrons
with
holes
in
the
valence

band.
BTE
1.
Boltzmann
Transport
Equation.
2.
broadband
terminal
equipment.
BTl
1.
British
Telecom
International.
2.
Broadband
Trial
Integration.
An
ACTS
project
to
demonstrate
the
role
of
Quality
of
Service

(QoS)
on
Internet
Proto-
col
(IP)
over
ATM
in
order
to
develop
optimization
data
for
networks
and
to
improve
user
perception
of
network
services.
The
project
involves
development
of
an

integrated
IPv6
and
switched
ATM
multicast-
ing
network
with
QoS
support of user-controlled
bandwidth
and
delay.
The
project
is
designed
in
three
phases,
the
establishment
of
the
technical
platform,
implementation
of
signaling

and
management
of
rout-
ers
and
switches,
and
the
development
of
integrated
140
protocols.
International
connections
will
be
through
PVC-based
ATM
networks
using
UNI
4.0
SVCs
for
bandwidth
management.
See

BID,
BLISS,
BONA-
PARTE,
BOURBON,
UPGRADE,
WOTAN.
BTL
Bell
Telephone
Laboratories.
See
Bell
Labora-
tories.
BTM
See
broadband
transport
manager.
BTN
See
Billing
Telephone
Number.
BTRL
1.
B
Theory
Research

Labs.
2.
Breward
Teach-
ing
&
Research
Laboratories.
3.
See
British
Telecom
Research
Laboratories.
BTS
1.
Base
Transceiver
Station.
In
mobile
communi-
cations,
an
end
transmission
point.
2.
bit
test

and
set.
Btu
See
British thennal
unit.
BTU
basic
transmission
unit.
BTUInternationalA
major
supplier
of
thermal
pro-
cessing
systems
to
the
electronics
industry,
primarily
semiconductor
packaging
and
printed
circuit
boards.
bubble memory A

type
of
nonvolatile
memory;
it
doesn't
have
to
be
constantly
electrically
refreshed
to
retain
the
data.
Bubble
memory,
as
used
in
com-
puters,
consists
ofa
thin
layer
of
material
that

has
magnetic
properties.
A
magnetic
field
is
used
to
ma-
nipulate a circular
area
such
that
the
diameter
be-
comes
smaller,
forming
a
bubble.
bucket
truck
See
cherry
picker.
buffer
1.
A

circuit
or
device
designed
to
separate
elec-
trical
circuits
one
from
another.
2.
A
physical
or
elec-
tronic
storage
device
designed
to
compensate
for
a
difference
in
the
rate
of

use
or
flow
of
objects
or
in-
formation.
Generally
a
buffer
is
intended
to
increase
speed
of
access
and
efficiency.
In
a
computer,
a
buffer
is
often
used
as
a

storage
area
for
frequently
accessed
information,
so
the
software
doesn't
have
to
con-
stantly
access
slower
storage
devices
such
as
a
hard
drive,
if
sufficient
fast
access
chip
memory
(e.g.,

RAM)
is
available.
Cut
and
paste
functions
make
use
ofa
buffer.
Data
in
a
buffer
tends
to
be
temporary
and
volatile.
See
cache,
frame
buffer,
RAM
disk.
buffer, cable A
layer
of

material
to
protect
inner
or
outer
components
from
abrasion,
moisture,
pressure,
flexing,
or
tampering.
In
fiber
optic
cable
assemblies,
the
buffer
layer
encircles
the
coating,
cladding,
and
inner light-conducting
core
to

provide protection
from
the
elements.
See
swelling
tape.
buffer box
See
Logical
Storage
Unit.
buffer condenser A
condenser
installed
in
an
elec-
tronic
circuit
to
provide
protection
to
other
compo-
nents
by
reducing excessive voltages, especially
surges.

buffermemory, bufferstorage
Electronic
memory,
usually
RAM,
used
for
information
storage
and
re-
trieval,
particularly
for
applications
programs
which
make
use
of
chunks
of
information
that
are
frequently
recalled.
See
buffer,
cache.

bugA
small,
concealed
listening
device
used
in
sur-
veillance
and
espionage.
Placing
a
covert
bug
in
a
room
or
on
a
phone
line
is
almost
always
illegal.
The
term
is

also
used
in
conjunction
with
small,
hobbyist
transceiver
projects
for
electronics
education,
wire-
less
intercoms,
child
monitors,
and
other
legitimate
uses.
See
bug,
software/hardware;
wire
tapping.
© 2003 by CRC Press LLC
bug, software/hardware A software
or
hardware

error
that
adversely
affects
operations
or
user
inter-
action.
Grace
Hopper
is
credited
with
relating
the
first
story
about
a
computer
bug
that
was
found
by
a
tech-
nician,
and

for
preserving
the
bug
itself
in
a
log
book.
This
story
has
long
been
a part of
hacker
lore
as
the
origin
of
the
term
"bug"
in
computer
technology.
The
bug
in

the
story
apparently
was
moved
to
the
Smith-
sonian
Institution
in
the
early
1990s
(after
an
earlier
unsuccessful
attempt
to
have
it
accepted)
but
was
not
immediately
exhibited.
However,
there

are
earlier
an-
ecdotes
about
bugs
in
industrial
settings
that
indicate
the
term
may
go
back
decades,
if
not
longer.
Removing
bugs
from
software
(debugging)
is
an
art
form,
and

not
all
programmers
who
are
good
at
writ-
ing
code
are
good
at
finding
and
correcting
bugs.
Unfortunately
for
developers,
removing
one
bug
of-
ten
introduces
one
(or
more)
elsewhere.

Unfortu-
nately
for
consumers,
some
commercial software
vendors
release
products
knowing
they
are
full
of
bugs,
and
there
are
no
specific
regulations
prohibit-
ing
it.
Because
computer
technology
is
technical,
the

user
may
not
know
whether
a
problem
is
from
bugs
or
from
incorrect
use
of
the
software.
Another
unfortunate
aspect
to
bugs
is
that
companies
often
combine
software
enhancements
with

bug
fixes
and
sell
the
new
product
as
an
upgrade
with
no
guar-
antee
that
it
is
more
robust
than
the
previous
version
(sometimes
it
is
less
so).
This
situation

is
like
buy-
ing
a
$15,000
car
with
a
faulty
engine,
and
having
the
manufacturer
refuse
to
fix
it
and,
instead,
advise
you
to
pay
$5,000
to
upgrade
to
next

year's
model.
When
you
do,
you
find
that
the
engine's
been
fixed,
but
the
axles
are
defective,
and
the
car
has
racing
stripes
that
you
didn't
want
in
the
first

place.
This
situ-
ation
in
the
software
industry
won't
change
until
con-
sumers
stop
buying
substandard software
and
en-
hanced
upgrades,
and
support
instead
the
more
re-
sponsible
vendors
who
provide

patches
for
bugs
sepa-
rately
from
releases
of
enhanced
versions.
bug, telegraph A
telegraph
lever
which,
depending
upon
its
position,
can
be
used
to
send
dots
or
dashes
to
partly
automate
transmission.

build
1.
An
increase
in
diameter
ofa
line
or
object
attributable
to
insulating
materials.
2.
In
software
de-
velopment,
the
process
of
combining,
compiling,
or
linking
code
so
as
to

build
an
application.
bulb
The
sealed
glass
enclosure
for
an
incandescent
or
fluorescent
lamp.
Bulbs
provide
protection
for
the
gaseous
environments
and
the
delicate
filaments
that
they
enclose.
See
Edison,

Thomas
Alva;
lamp.
bulkencryption
Simultaneous
encryption
ofa
group
or
set
of
communications,
such
as
multiple
data
mes-
sages
or
multiple
channels
on
a
broadcast
medium.
bulkeraser, bulkdegausser
An
electromagnetic
de-
vice

designed
to
save
time
by
clearing
the
data
from
a
large
number
of
floppy
disks
at
one
time.
By
rear-
ranging
the
particles
on
the
physical
disk,
the
elec-
tronic

infonnation
is
destroyed.
It
is
handy
for
recy-
cling
the
diskettes
or
for
providing
a
measure
of
se-
curity
with
data
that
needs
to
be
destroyed.
It
is
wise
to

keep
magnetic
storage
media
away
from
computer
monitors,
which
have
magnets,
or
you
may
inadvert-
ently
erase
or
damage
the
data
on
them.
A
large-scale
pirate
software
vendor,
who
was

apprehended
in
Van-
couver,
B.C.,
is
rumored
to
have
had
a
bulk
eraser
in
a
storage
cabinet
wired
to
a
button
under
the
service
counter
to
destroy
evidence
in
the

case
of a
police
raid.
See
diskette.
bulkstorage
Media
on
which
large
amounts
of
elec-
tronic
data
can
be
stored.
The
amount
of
storage
that
constitutes
large
keeps
increasing.
In
the

mid-1970s,
a
tape
holding
100
kilobytes
was
considered
bulk
storage!
In
the
mid-1980s,
a writable
optical
disk
holding
600
MBytes
was
bulk
storage.
Now
hard
disks
and
tapes
holding
4
GBytes

or
more
are
being
bundled
with
consumer
machines.
bulletin
board
system
BBS.
The
forerunner
to
the
Internet,
BBS
systems
are
typically
individual
com-
puters
set
up
for
public
or
private

modem
access,
by
a
number
of
users,
on
which
there
are
shared
files,
mail,
and
chat
services.
The
administrator
is
usually
called
the
SysOp
(System
Operator).
In
the
late
1970s

and
early
1980s,
it
was
extremely
rare
for
a
BBS
to
be
password-protected;
there
was
open
access
to
all.
Unfortunately,
persistent
abuse
has
made
this
type
of
BBS
almost
extinct.

In
the
mid-80s,
there
were
still
many
BBSs
running
on
TRS-80s,
Color
Computers
(CoCo),
Commodore
64s,
Apple
lIe's,
and
Amigas,
with
only
5
or
10
MBytes
of
hard
drive
storage

for
the
entire
system.
BBSs
have
since
become
more
so-
phisticated,
offering
credit
card
payment
options,
and
increasingly
are
being
linked
to
the
Internet
through
telnet.
See
FidoNet.
bump contacts
Small

conductive
lumps
on
electronic
circuits
that
protrude
to
enhance
electrical
contact,
such
as
those
that
allow
chips
to
touch
terminal
pads.
bunch strandingA
technique
used
to
combine
wires
so
they
fit

tightly
together,
with
individual
strands
retaining
the
same
directional
relationship
to
one
an-
other
to
form
a
stranded
wire.
Stranded
wire
is
use-
ful
in
situations
where
flexibility
is
desired

or
when
the
electrical
properties
of
the
wires
are
influenced
by
proximity
to
others.
bunching
An
alternating
convection-current
effect
in
an
electron
stream
caused
by
velocity
modulation.
Bunching
is
quantified

as
a
parameter
based
on
the
relationship
of
the
depth
ofvelocity
modulation
to
the
absence
of
modulation. Used
in
electron
tubes
to
generate
ultrahigh
and
microwave
frequencies.
See
klystron.
Bundesamt
fur

Zulassungen
in
der
Tele-
kommunikation
BZT.
A
German
telecommunica-
tions approval authority established
in
the
early
1980s.
bundled
1.
Combined
products
or
services,
some-
times
from
a
variety
of
manufacturers,
offered
at
a

combined
price.
Phone
and
cable
companies
often
have
bundled
or
packaged
deals, such
as
regular
tele-
phone
service
and
Caller
ID-related
services
offered
at
a
flat
rate,
or
movie
and
educational

channels
com-
bined.
Software
products
are
often
bundled
with
com-
puter
systems.
Operating
systems
are
almost
always
bundled
with
computers,
often
along
with
various
141
© 2003 by CRC Press LLC