Fiber Optics Illustrated Dictionary - Part 18 potx

Fiber
Optics
Illustrated
Dictionary
card An electronic printed circuit
board,
especially
one
that
is
easily
dropped
into a
card
slot by adealer
or
consumer.
See
printed circuit
card,
punch
card.
card hopperIn
mechanisms
that
hold
and
feed
punch
cards,
the

holder
in
which
the
cards
are
stacked
next
to
the
feed
mechanism
for
processing.
See
card
stacker.
Card Issuer Identifier Code CnD. A calling card
identification
scheme.
There
are
restrictions
on
which
carriers
can
issue/use
cnD
cards.

card slotA
slot-shaped
data
connector
within
an
elec-
tronic
system
for
the
insertion
of
printed circuit
board
peripherals.
Cards
frequently
consist
of
graphics
con-
trollers,
drive
controllers, serial
and
parallel ports,
network connectors,
and
others.

PCI
is
a
common
format
for
computer
card
slots.
See
edge
connector,
printed circuit
board.
cardstacker In
mechanisms
that
hold
and
feed
punch
cards,
the
exit
tray
in
which
the
cards
are

stacked
af-
ter processing.
There
may
be
several
of
these,
with a
card sorter determining
the
destination stacker
from
holes
in
the
cards.
See
card
hopper.
Cardano, Girolamo (1501-1576) Also known
as
Hieronymus
Cardanus,
Cardano
was
an
Italian
math-

ematician, physicist,
and
physician
to
kings
who
authored
many
important historic publications,
in-
cluding
De
subtilitate
(On
subtlety,
1550),
describ-
ing
the
accumulated knowledge
about
amber,
with a
definite
statement
that
the
properties
of
lodestone

and
amber differed
in
significant
ways.
He
further
de-
scribed
these
differences.
He
also
proposed
the
im-
portant mathematical notion
of
imaginary
numbers
and
made
a systematic study
of
probabilities.
See
amber,
lodestone.
Girolamo Cardano - Magnetism Pioneer
A multitalented pioneer

in
mathematics and phys-
ics,
Girolamo
Cardano
contributedimportant insights
to
our
understanding
of
magnetism
(e.g.,
properties
of
lodestone)
and
theoretical
mathematics
in
the
1500s.
CardBus A 32-bit computer
data
bus
designed
for
use
with
PCMCIA
cards.

The
CardBus
was
designed
to
succeed
the
PC
Card
standard.
See
Personal
Com-
puter
Memory
Card
Interface Association.
162
cardiode pattern Adiagrammatic representation
of
the
directional response
of
various transmitting
and
receiving devices: antennas, speakers,
etc.
It
derives
its

name
from
the
symmetrical, heart-shaped pattern
that
is
typical.
See
antenna
lobe.
Carnegie-Mellon U
Diversity
This
U.S.
educational
institution
is
known
for
many
contributions
to
tele-
communications.
One
of
the
more
familiar
is

the
An-
drew
File System
(AFS)
used
on
computer
networks.
More
recently, developers
have
created a working,
campus-wide wireless data communications system
which
serves
as
a
model
for
similar installations else-
where
and
AFS
is
evolving
into
a powerful, distrib-
uted network protocol with a
new

name
and
some
in-
teresting
new
capabilities.
carrier
1.
A wave
of
constant
or
known
amplitude,
frequency,
and
phase, which
can
be
modulated
by
changing
one
of
these characteristics.
See
carrier
wave, carrier frequency,
Tl.

2.
An entity that can
carry
an
electrical charge through a solid.
3.
An
in-
formation-providing radiant energy
from
space.
The
four
known
categories
of
carriers
are
electromagnetic
radiation, solid bodies, elementary
cosmic
rays,
and
gravitational waves.
carrier, communications A provider of
communi-
cations circuits.
Common
(usually
the

local phone
company)
and
private carriers
are
distinguished
by
degree
of
regulation
and
right
to
access
of
service
by
the
public.
The
designation
of
communications
car-
rier
was
intended
to
encompass
companies with their

own
transmission facilities,
as
opposed
to
companies
that
lease
or
buy
equipment or services
for
resale, but
the
general public often
uses
the
phrase
more
loosely
to
include
all
long-distance
companies.
carrier, GPS AGPS-related radio
wave
with
at
least

one
characteristic (such
as
frequency,
phase,
ampli-
tude)
that
can
be
varied (modulated)
from
a
known
reference
value.
See
Global
Positioning Service.
Carrier
Access
Code
CAC.
See
Access
Code.
carrierbandA
range
of
adjacent

frequencies
that
can
be
modulated
to
carry information, such
as
radio
broadcast waves (without a carrier
wave,
multiple
frequencies could
not
be
transmitted without signal
overlap and disruption).
See
band, carrier, carrier
wave,
modulation.
carrierbypass A
phone
service providerdirect-con-
nect link
to
the
customer's
lines,
bypassing

the
local
phone
carrier.
Some
long-distance
companies
provide
services through a carrier bypass
in
order
to
provide
faster service or less expensive service
by
avoiding
Carrier
Common
Line Charges.
See
Access
Charge.
Carrier Common Line Charge
CCLC.
A charge
paid
by
phone services providers
to
a primary

car-
rier
for
using their switched network
lines.
Typically
paid
by
long
-distance providers.
See
Access
Charge,
carrier bypass.
carrier detect
CD.
Asignal generated by a
modem
that
operates over
phone
lines
to
indicate whether
the
phone
carrier
is
present
and

the
line
can
be
dialed.
Many
modems
have
an
LED
to
indicate
the
presence
of
the
carrier signal.
The
command
to
the
modem
for
carrier detect
is
typically &Cl.
© 2003 by CRC Press LLC
carrierfrequency
1.
The

frequency
ofacarrier
wave
intended
to
be
modulated
by
the
wave
containing
the
information.
See
carrier
wave.
2.
In
the
Global
Posi-
tioning System (GPS), the frequency
of
the
unmodulated
fundamental
output ofa
radio
transis-
tor.

3.
The
reciprocal
of
the
period
ofa
periodic
car-
rier.
See
center
frequency.
Carrier
Identification Code
CIC.
A short
code
to
identify
uniquely
a secondary
phone
service carrier
for
routing
and
billing.
It
was

formerly
three
charac-
ters,
but
the
Industry Carrier Compatibility
Forum
in
1988
and
Bellcore
in
1989
informed
the
Chiefof
the
Common
Carrier Bureau that
four
characters
were
needed
to
meet
increasing
demand.
The
numbers

are
issued
by
the
North American
Numbering
Plan
Ad-
ministration
(NANPA)
to
authorized
entities.
The
ex-
pansion
from
three
to
four
digits
was
termed
the
Plan
of
Record
(POR).
The
implementation of

this
plan
would
not
be
trivial
as
it
involved administrative
changes
and
expenditures
on
the
part
of
Local
Ex-
change
Carriers
(LECs)
and
change-over
expenses
to
anyone
publishing
materials with
CICs
(directories,

letterheads,
marketing
materials,
etc.).
It
also
required
procedures
and
priorities
for
conserving
and
reusing
scarce
CIC
resources.
By
the
mid-1990s,
Bellcore
began
assigning·four-
digit
Feature
Group
D
CICs.
In
1998,

this
was
fur-
ther
changed
to
aprefix (e.g.,
"1
0+1
Oxxx")
followed
by
the
number,
thus
bypassing
the
subscription
car-
rier
(which
would
use
the
prefix code"1").
See
Ac-
cess
Code,
North

American
Numbering
Plan.
carrierselect keys
Buttons
included
on
a
phone
(usu-
ally
a
payphone)
to
provide
the
caller with a quick
way
to
select
a long-distance
provider,
thus
not
hav-
ing
to
key
in
extra

digits
for
access
codes.
carrier selection Selection
by
a
phone
customer of
a
long-distance
provider,
usually
done
at
the
time
of
ordering
the
service,
but
it
can
be
changed
at
any
time.
If

you
select
aprimary long-distance
carrier,
you
will
be
able
to
access
the
service
by
dialing
"1"
plus
the
number.
For
alternate long-distance
companies,
you
have
to
enter
additional
digits
or
access
codes

to
com-
plete
a
call.
There
are
many
long-distance
companies,
each
offering
better
features
and
lower
prices
than
the
next.
Evaluate
these
carefully
before
switching
ser-
vices,
as
there may be inconveniences, hidden
charges,

or
limitations
that
are
not
apparent
from
the
advertising literature
and
that
may
result
in
service
that
is
limited
and
not
necessarily cheaper
in
the
long
run.
See
Access
Code,
carrier
bypass.

carrier sense
The
capability ofa station
to
continu-
ously
monitor
other stations
to
see
if
they
are
trans-
mitting.
See
Carrier
Sense
Multiple
Access.
CarrierSense MultipleAccess
CSMA.
A
listen-and-
send
protocol
used
on
local
area

networks
(LANs).
A
system
readying
to
transmit
first
probes
the
net-
work
to
see
if
the
line
is
clear;
in
other
words,
it
en-
sures
that
another
workstation
is
not

transmitting.
If
the
coast
is
clear,
it
sends
the
transmission.
This
pro-
tocol
does
not
guarantee that collisions don't
occur;
it
simply
reduces
the
likelihood of
an
immediate
col-
lision.
Various
versions
of
CSMA

exist
to
enhance
its
efficiency
and
provide greater collision detection
and
avoidance.
Carrier
Sense Multiple Access with Collision
Avoidance
CSMA/CA.
A version of Carrier
Sense
Multiple
Access
that
is
used
in
Ethernet
systems
in
association with
Media
Access
Control
(MAC)
pro-

tocols
to
integrate collision detection
with
time-di-
vision multiplexing
(TDM).
It
aids
in
improving
ef-
ficiency
in
CSMA
systems.
See
Carrier
Sense
Mul-
tiple
Access.
Carrier
Sense MultipleAccess with Collision De-
tection
CSMA/CD.
Aversion ofCSMA
with
added
traffic

flow
control capabilities
to
detect
collisions,
in
order
to
increase
the
efficiency of
flow
ofinfor-
mation
on
a
local
area
network
(LAN).
CSMA/CD
is
not
ideal
for
all
implementations.
In
satellite
com-

munications,
for
example,
the
transmitting
Earth
sta-
tions
cannot
engage
carrier sensing
on
the
uplink
due
to
its
point-to-point nature.
See
Carrier
Sense
Mul-
tiple
Access.
carrier
shifting A technique of moving
an
entire
modulated
wave

sequence
in
a positive
or
negative
direction
with
respect
to
its
midpoint,
without
chang-
ing
the
overall
shape
of
the
envelope.
Carrier shift-
ing
is
often
used
to
manipulate
mathematically
a
wave

or
to
recreate a
wave
based
upon
only
partial infor-
mation
(e.g.,
sideband).
See
phase shift
keying.
carrier
shifting fault An undesirable condition
in
transmitting a modulated carrier
wave,
in
which
the
envelope,
the
range
ofamplitude-modulated signals
above
and
below
the

midpoint of
the
waves,
is
un-
balanced.
carriersignalA
continuous
radiant
wave
that
can
be
modulated
to
add
information
to
the
wave.
Carrier
signals
are
modulated
in
a variety of
ways;
the
two
most

familiar
are
amplitude modulation
(AM)
and
frequency
modulation
(FM).
One
of
the
first
research-
ers
to
search
for
a
way
to
add
information
to
acarrier
wave
was
R.
Fessenden,
an
American

inventor
who
devised
the
hot-wire barretter
and
a high-frequency
wave
generator
in
1901.
Later,
1.
Carson
studied
the
mathematical properties ofcarrier
signals
and
pro-
posed
ways
ofcarrying information
by
manipulating
and
recreating
the
signal
at

the
receiving
end,
thus
saving transmissions bandwidth.
See
Carson,
John
Renshaw;
Fessenden,
Reginald
Aubrey;
modulation;
single
sideband.
carrier
synchronization In radio broadcasting, a
carrier
wave
is
used
to
carry a signal
through
a
pro-
cess
called
modulation,
wherein

information
is
added
to
the
carrier
wave.
Various
means of sending
the
modulated
wave
have
been
developed,
some
of
which
send
only
the
sidebands,
some
of
which
send
one
side
of
the

signal
and
recreate
the
other,
etc.
Consequently,
at
the
receiving
end,
the
receiver
has
to
be
designed
so
it
can
properly process
the
type
of
wave
that
is
being
received.
In

some
cases,
this
situation involves
the
creation
ofa
reference
carrier
that
is
synchronized
with
the
received
signal.
See
Carson,
John
R.;
single
sideband.
carrier
to interference ratio
CIR.
A quantitative
description of
the
effective transmission
in

relation
163
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
to
the
(undesired)
interference
affecting
that
transmis-
sion.
This
ratio
is
of
special
interest
to
wireless
com-
munications engineers
in
designing transmissions
components
such
as

antennas
and
transceiving
equip-
ment.
It
is
ofincreasing
importance
as
vendors
seek
to
increase
the
capacity ofexisting
systems
without
degrading
the
signal
to
the
point
that
the
customers
are
unhappy
with

the
service.
carrier
wave A single-frequency
wave
that
carries
the
transmission
by
being
modulated
by
another
wave
containing
the
information.
Acarrier
wave
provides
multiple
channels
and
a
means
to
reduce
signal
over-

lap
through
multiplexed
broadcast
waves.
See
carrier.
carrierless amplitude and phase modulationCAP
modulation.
A
coding
technique,
based
upon
quadra-
ture
amplitude
modulation,
used
in
Digital
Subscriber
Line
(DSL)
transmissions.
See
discrete multitone,
modulation,
pulse
amplitude

modulation.
CARS
See
Cable
Television
Relay
Service
Station.
Carson, John Renshaw A mathematician
and
re-
searcher
at
Bell
Laboratories
who
contributed
math-
ematics
fundamentals
related
to
modulation
of
com-
munications
waves
that
provided
a

way
to
recover
the
whole
band
from
sideband
transmissions.
In
1915,
he
demonstrated
that
separate
channels
could
be
carried
on
each
of
the
sidebands
ofa
modulated
carrier
wave.
In
1922,

he
provided
a
mathematical
description of
frequency
modulation
(FM)
(and
is
somewhat
infa-
mous
for
having
disagreed
with
E.
Armstrong
about
the
feasibility
ofFM
transmissions).
He
was
awarded
the
Franklin Institute
Cresson

Medal
in
1939.
See
Armstrong,
Edwin
Howard;
Carson's
Rule.
Carson's Rule A
method
for
calculating
the
mini-
mum
bandwidth of a frequency-modulated signal
needed
to
transmit
the
desired communication. A
larger
number
ofsubcarriers
will
necessitate awider
Carson's
bandwidth.
Named

after
John
R.
Carson.
Carterfone A
commercial
device
developed
in
the
1960s
for
acoustically connecting
two-way
mobile
radio
communications
to
a
telephone
network
system.
Developed
by
Thomas
Carter,
who
battled
for
the

right
to
connect
into
the
public
phone
network,
the
system
became
known
through
an
important judg-
ment
by
the
Federal
Communications
Commission
(FCC).
Carter didn't
sell
many
of
the
devices,
but
AT

&T
saw
the
precedence
as
threatening
enough,
in
terms
of
its
implications
for
other
vendors,
to
obstruct
its
use.
See
Carterfone
Decision.
CarterfoneDecisionA
1968
landmark
judgment
by
the
Federal
Communications

Commission
(FCC)
in
which
existing
interstate
telephone
tariffs
that
pro-
hibited
subscribers
from
attaching
their
own
phone
equipment
to
existing
phone
lines
was
struck
down.
Carter
Electronics
had
sought
since

1966
to
acousti-
cally
interconnect
its
private
mobile
radio
systems
to
the
national
exchange
network
through
a voice-acti-
vated
system
that
started
the
radio
transmitter.
In
pur-
suing
its
own
right

of
access,
Carter
Electronics
paved
the
way
for
other
companies
as
well
and,
in
a
sense,
foreshadowing
the
divestiture of
AT&T.
As
a result of
the
Carterphone
Decision,
manufac-
turers
other
than
Western

Electric,
which
had
exclu-
164
sive
arrangements
with
AT&T,
no
longer
were
pre-
vented
from
using
the
resources,
and
the
interconnect
industry
was
born.
See
Carterfone,
Hush-a-Phone
de-
cision.
cartridge A

common
type
of magnetic removable
data
storage that
works
somewhat
like
a
floppy
dis-
kette
but
is
physically larger
in
size
and
significantly
higher
in
storage
capacity.
Cartridges
commonly
hold
between
200
Mbytes
and

1
Gbyte
of data uncom-
pressed. With the introduction
of
super-capacity
disks, 3.5" floppies that
can
store
more
than
1
00
Mbytes
of
data,
the
discrepancy
between
low-capac-
ity
cartridges
and
high-capacity floppies
is
less
than
low-capacity
floppy
drives.

Rewritable
CDs
are
now
beginning
to
compete
with cartridges
as
backup
stor-
age
devices
due
to
the
less
volatile
nature
of
the
data.
Carty,John
J.
(1861-1932) Chief
engineer
of
AT
&T
in

the
early
1900s
after serving
as
the
head
of
West-
ern
Electric's cable
department.
Carty
developed
the
frrst
two-wire
telephone circuit
and
the
phantom
cir-
cuit, through which three conversations could
be
transmitted
at
one
time
over
two

pairs
of
wires.
West-
ern
Electric purchased
the
rights
to
Lee
de
Forest's
Audion,
a three-electrode
tube,
in
time
for
Carty
to
fulfill
a promise
he
made
in
1909
to
provide
a trans-
continental telephone service

to
the
U.S.
west
coast
by
1914.
See
AT&T,
phantom
phone.
Carty,
John
J., Award for the Advancement
of
ScienceAtriennial
award
for
noteworthy
and
distin-
guished
accomplishment
in
science.
This
award
has
been
directed

towards
a different
field
every
three
years
since
1932.
It
was
established
by
AT&T.
CAS
1.
CentralizedAttendant
Service.
Acentralized
group
of
operators
servicing
systems
which
may
have
a
number
ofbranches within a
region.

2.
See
chan-
nel associated signaling.
3.
See
Communications
Applications Specification.
cascade
To
arrange
or
pattern
into
aseries
or
succes-
sion
of
steps
or
stages,
each
dependent
upon,
or
de-
rived
from
the

preceding,
often
in
a
falling
or
down-
ward
hierarchy.
Computer
menus,
file
systems,
ap-
plications
windows,
and
other graphical
and
logical
structures
are
often developed
with
a
cascade
struc-
ture.
Text
editing applications

sometimes
have
tele-
scoping
and
cascading outline capabilities.
Cascad-
ing
principles
and
properties
are
now
being
studied
with
relation
to
quantum
effects
and
harnessed
for
commercial
applications.
See
quantum
cascade
laser.
CASE computer-aided software

engineering,
com-
puter-assisted software engineering.
case sensitive
1.
Computer
software
data
or
processes
in
which
the
case
(lower
or
upper)
is
considered
sig-
nificant
to
the
meaning
of
the
text.
For
example,
file

names
on
Unix
systems
are
case
sensitive; that
is,
"MyFile.txt"
is
different
from
"myfile.txt".
Case
sen-
sitive
file
names
result
in
a greater
range
ofdescrip-
tive
naming
possibilities.
MS-DOS
systems
are
case

insensitive.
AmigaOS
is
partly
case-sensitive,
forgiv-
ing
about
case
when
traversing
directories
in
the
shell,
but
allowing
file
names
that
can
be
distinguished
from
one
another
by
case.
2.
In

word
processing, search
and
replace
routines
can
usually
be
configured
to
be
© 2003 by CRC Press LLC
case
sensitive
or
case
insensitive,
depending
upon
your
needs.
3.
On
the
Web,
URLs
are
case
sensitive,
but

for
the
convenience
of
users
many
browsers
will
resolve
the
cases
in
a
forgiving
manner,
to
load
a
Web
page
even
if
the
case
is
misspecified.
This
feature
is
not

characteristic
of
all
browsers,
so
it's usually
bet-
ter
to
type
in
the
case
correctly.
case sensitive password
For
access
to
secure
com-
puter
systems,
most
password
fields
require
an
exact
match,
hence

are
case
sensitive,
in
order
to
provide
a
greater
variety
of possible
passwords
and
thus
in-
creased
security.
Case
sensitivity
also
increases
the
total
number
of
possible
passwords,
which
is
impor-

tant
if
it
is
a
multiuser
environment
with
a
limit
on
the
number
of
characters
in
the
password
(e.g.,
eight
characters
).
Cassegrain antenna, Cassegrainian
antenna
A
parabolic
antenna
arrangement
in
which

the
feed
is
located
near
the
vertex
ofa
concave
surface
of
the
main
reflector,
and
a
secondary
reflector
is
located
near
the
focal
point
and
aligned
to
be
within
the

fo-
cus
of
the
main
reflector.
A
beam
is
thus
redirected
from
the
feed
unit
through
the
secondary
reflector
to
the
main
reflector
to
radiate
a
beam
that
is
parallel

to
the
axis
of
the
main
reflector.
A
Cassegrain
feed
is
one
type
of
arrangement;
hom
feed
is
another.
Cas-
segrain
antennas
require
more
careful
alignment
and
more
parts
than

a
hom
feed
antenna
and
thus
tend
to
be
used
in
higher
end,
more
expensive
applications.
Due
to
the
redirection of
the
reflection,
they
stay
cooler
than
hom
feed
arrangements
and

are
thus
suit-
able
for
hotter
climates.
See
antenna;
hom
feed;
para-
bolic
antenna;
Ramsden,
Jesse.
Cassegrain,Guillaume
(dates
unknown)
Apparently
a
French
founder
and
sculptor
who
developed
a
cen-
ter

mirror
telescope
even
before
Newton
constructed
a
reflecting
telescope.
In
1672,
Cassegrain
proposed
using
a
main
mirror
with
a
hole
in
the
center,
with
a
smaller
hyperboloid
mirror
to
reflect

back
the
image
through
the
hole
to
an
eyepiece.
This
arrangement
results
in
a
compact
design
and
minimal
spherical
and
chromatic
aberrations
in
the
image.
It
is
the
same
general

configuration
of
some
of
the
advanced
tele-
scopes
of
today.
See
Cassegrain
antenna.
cassette tape A
portable
recording
and
playing
me-
dium
consisting
of
a long narrow magnetic tape
wound
onto
reels
protected
by
a
roughly

rectangular
plastic
case.
Cassette
tapes
come
in
a
variety
of
tape
widths
and
are
used
for
both
sound
and
video.
Some
audio
tapes
are
wound
onto
the
reel
in
a

loop
to
enable
continuous
playing,
but
most
are
manually
turned
over
or
mechanically
rewound.
Cassettes
are
commonly
used
for
consumer
audio
and
backup
and
archiving
of
computer
data.
Very
small

cassette
tapes
are
used
in
answering
machines
and
small
tape
re-
corders
designed
for
maximum
portability
(and,
in
some
cases,
minimum
visibility).
Cassette
tapes
for
consumer
audio
almost
completely
replaced

reel-to-
reel
tape,
then
began
to
be
supplanted
by
audio
CDs
and
other
digital
audio
technologies.
See
CD,
DAT,
leader,
reel-to-reel.
Cassini A
spacecraft
designed
to
travel
through
the
solar
system

and
send
back
information
to
be
evalu-
ated
by
scientists
to
teach
us
more
about
our
plan-
etary environment
and
the
universe.
The
Cassini
spacecraft
has
many
tasks
to
perform
on

its
way
to
the
planet
Saturn.
Flyby
targets
include
Venus,
Earth,
~~;~~~~;~~~~~:;~~~~t~~~;~i~:~b~f~<'11
maneuvers
and
flybys
needed
to
take
it
on
its
seven
year
journey
to
Saturn.
The
telecommunications
and
guidance

systems
associated
with
the
Cassini
mission
are
some
of
the
most
sophisticated
to
date
and
will
teach
us
much
about
how
far
and
how
well
we
can
transmit
information
to

and
from
the
comers
of
the
Galaxy.
castellationAn
indented
pattern
or
surface
ofa
regu-
lar,
repeated
nature.
For
example,
the
battlements
on
castles
are
castellated.
Castellated
protruberances,
or
thin
pads

of
conductive
materials,
are
often
incorpo-
rated
into
the
edges
of
electronic
circuit
boards
to
pro-
vide
contact
points
for
electrical
connections.
Grat-
ings
are
often
castellated
components.
cat,
Cat

abbrev.
category.
In
cabling,
Category,
or
Cat
followed
by
a
number
denotes
industry-specific
cabling
standards.
See
category
ofperfonnance.
CAT
1.
Call
Accounting
Terminal.
An
AT&T
term
for
a microprocessor-equipped
device
that

records
call
activity
in
order
to
provide
automated
account-
ing
information.
2.
See
computer-aided teaching,
computer assisted instruction.
3.
See
Council
for
Access
Technologies.
catadioptric devices
Devices
that
utilize
both
opti-
cal
reflection
and

refraction
to
control
the
travel
of
light
through
the
device,
often
to
produce
an
image
for
viewing
or
transission.
Depending
upon
the
in-
strument,
the
catadioptric
configuration
may
be
in-

tended
to
shorten
the
length
of
the
barrel
ofa
view-
ing
device
or
process
the
light
signal
as
it
is
being
reflected
and
refracted.
Catadioptric
principles
are
used
in
a

variety
of
astronomical
telescopes,
robot-
ics
imaging
technologies,
and
some
digital
video
cam
applications.
Catarra
See
PDA
marcrobrowser,
SoftSource
Corp.
category, wiring
See
category
of
performance.
category
of
performance
Cabling
and

component
standards
that
have
been
defined
to
promote
and
fa-
cilitate intercompatibility of
products
from
different
vendors.
These
standards
are
widely
used
in
the
phone
and
computer
network
industries,
especially
Cat
5.

The
categories
of
performance
focus
on
the
through-
put
of
the
transmissions
rather
than
the
specific
ma-
terials
used
to
construct
individual
cables.
They
are
self
certifying
in
the
sense

that
the
vendor
is
respon-
sible
for
testing
and
maintaining
quality
and
manu-
facturing
standards
to
provide
the
performance
cat-
egories
detailed
in
the
Categories
chart.
catbode
(symb.
-
K)

1.
The
negative
terminal
of
an
electrolytic
cell.
2.
The
positive
terminal
of
current-
supplying
primary
cell.
3.
In a
moving
electron
sys-
tem
such
as
an
electron
tube,
the
electron-emitting

portion,
directed
toward
an
anode,
often
a
thin
metal
165
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
plate,
usually
passing through acontrolling
grid.
The
electron beam-emitting end
of
a cathode-ray
tube
(CRT).
See
cathode-ray
tube,
phototube, photomul-
tiplier

tube.
Cathode-Ray Tube - Basic Parts
Cathode
in
Electron
Tube
The
cathode
is
one
of
the
three
essential elements
of
an
electron
tube,
emitting the electrons that
are
at-
tracted
to
the
anode.
In
this
tube,
the
filament acts

as
the
cathode.
The
movement
of
the
electron
beam
across
the
dis-
play surface excites
the
phosphors
so
that
they
selec-
tively
light
up
(fluoresce)
and
remain
visible
for
a
few
moments.

The
sweep
of
the
beam
is
very
fast
so
that
perceptually
humans
will
'see'
the
entire
frame
as
one
image
rather than
as
a series ofconstantly refreshed
lines.
Sometimes
agrating called a
shadow
mask
is
inserted

between
the
beam
and
the
coating
to
further control
and focus the beam
to
provide a crisper display.
Cathode-ray
tubes
can
be
short persistence or
long
persistence.
Long
persistence
means
the
phosphors
remain lit
for
a longer period
of
time,
and
the

screen
may
not
have
to
be
refreshed
as
often
to
keep
an
im-
age
visible.
The
refresh
rate
on
most
current
monitors
is
60
frames
Cathode-ray
tubes
are
essential
components

in
many
types
of
electronics
devices.
They
are
widely used
as
display devices for televisions, radar scopes, oscillo-
scopes,
computer
monitors,
etc.
This
diagram
of
a his-
toric
electromagnetic-deflection cathode-ray
tube
pro-
vides
an
example
of
the
basic,
essential components.

phosphor coating
on
inside of
tube
deflecting coils
anodes
cathode rayAn
ionized
region,
composed
ofa
stream
ofelectrons influenced
by
an
electric
field,
emanat-
ing
from
a
cathode.
See
cathode-ray
tube.
cathode-ray tube
CRT.
Adisplay device consisting
ofaclosed
tube

of
glass
with
the
air
removed;
it
con-
tains
an
electron-emitting
gun
at
one
end
and
a
coated
surface
at
the
other.
The
cathode-ray electron
beam
emanates
from
the
cathode
and

passes
through
a
mag-
netic
field
that
controls
the
beam.
By
sweeping
across
the
coated inside surface
of
the glass, a frame
is
fonned
on
a
raster
display
and
a
vector
is
formed
on
a

vector
display,
either
of
which
can
be
seen
through
the
glass
from
the
outside.
cathode
(filament)
Categories ofPerformance
Category
Transmission
Rate
Notes
Cat
1
Not
used
Cat
2
Not
used
Cat

3
Up
to
16
megahertz
24-gauge
wire.
Typically
used
in
voice
communications
and
lower end data communications, such
as
Token-Ring and
10-Mbps
Ethernet
networks.
Cat
4
Up
to
20
megahertz
Digital
voice
communications
and
data

networks,
e.g.,
Token-
Ring.
Cat
5
Up
to
100
megahertz
24-gauge
wire
with
more
stringent
fabrication
requirements
than
Cat
3
(e.g.,
better
shielding).
Typically
used
in
higher
end
data
communications

and
high-grade
or
digital
voice
applications,
particularly
high-bandwidth
ones
such
as
videoconferencing.
Examples
include
FDDI,
lOOBase-T,
lOO-Mbps
Token-Ring
or
Ethernet.
See
twisted
pair
for
a
diagram.
166
© 2003 by CRC Press LLC
per
second,

a
rate
that
is
fast
enough
to
appear stable
and
not
flickering
to
the
human
eye.
Color
CRTs
typi-
cally
have
three
beams,
red,
green,
and
blue
(RGB).
The
cathode-ray
tube

is
fragile
and
large (regretta-
bly)
and
is
typically
encased
in
aprotective
console.
It
is
not
advisable
for
laypersons
to
open
the
back
of
a
CRT
device,
as
there
is
a

danger
ofelectric
shock
from
the
stored charge.
CRTs
were
being used
as
computer
display
devices
by
the
early
1950s
but
did
not
become
regularly associated
with
microcomput-
ers
until
1976.
CRTs
are
commonly

used
for
moni-
tors
(computers,
video
editing,
scopes)
and
television
screens.
See
Crookes
tube;
flat
panel
CRT;
frame;
Geissler
tube;
interlace; screen
saver;
shadow
mask;
Zworykin,
Vladimir
Kosma.
cathodic protection
In
many

wiring installations,
bare
wire
is
used,
so
corrosion
is
a significant
con-
cern.
One
of the ways
to
prevent corrosion
and
buildup
is
by
running
a negative
charge
through
the
wire
to
repel
negative
ion
materials

such
as
chlorine.
CATNIP
See
Common
Architecture
for
Next
Gen-
eration Internet Protocol.
CATS
See
Consortium
for
Audiographics
Telecon-
ferencing
Standards.
CATV
I.
Cable
Television.
A
system
that
delivers
fre-
quency-segmented
television

programming
channels
to
subscribers through physical cables, usually
75-ohm
coaxial
cables.
The
full
bandwidth of
cable
is
not
typically
used,
partly
due
to
the
extent of
the
subscriber's service
and
partly
due
to
the
insertion
of
non-pro

gram-carrying
guard
bands
that
act
as
sepa-
rators
to
keep
individual channel transmissions
from
interfering
with
one
another.
2.
Community
Antenna
Television.
A
large
antenna,
shared
by
a
community,
to
intercept broadcast stations that
are

not
accessible
via
small,
individual
antennas.
Sometimes
commer-
cial
communities
(motels, resorts, condominiums)
will
make
arrangements
to
install apowerful
antenna
and
rebroadcast
or
channel
the
signals
to
individual
units.
In
many
cases,
this

will
require
a
special
license
as
there
are
laws
protecting
broadcasters
from
hav-
ing
their
programs
rebroadcast.
catwhiskerA
fine
metal
thread
resembling
the
arched
shape
of a cat's
whisker,
used
in
early

radio
wave
detecting
crystal
sets.
The
catwhisker contacted
the
crystal
on
one
end
and
was
secured
to
a
metal
con-
ductive
support
on
the
other
end.
Some
enclosed
sets
used
a catwhisker

that
was
fixed
in
place
at
the
fac-
tory.
Prior
to
the
commercialization
of
crystal
sets,
it
was
known
as
a
feeler.
See
crystal
detector.
CAU
See
controlled
access
unit.

CAY
See
constant
angular
velocity.
cavityA
depression,
hole,
indentation,
or
pit,
which
may
be
of
any
size.
In various
media,
cavities ofpre-
cise
characteristics
are
created
in
the
surface
so
they
can

later
be
used
to
deflect
radiant
waves
or
carefully
focused
laser
light
beams.
The
deflections
pass
into
some
kind
of
pickup
mechanism
(read
mechanism)
so
the
encoded
information
can
be

recreated
and
pre-
sented.
Thus,
cavities
are
at
the
heart
of
many
opti-
cal
recording technologies,
CDs,
for
example.
cavity magnetronAn
early
British
innovation
in
radar
systems,
developed
in
1940,
that
enabled

the
use
of
extremely short
waves
(microwaves).
Thus,
it
was
possible
to
design
more
compact
antennas
and
im-
prove
the
quality of
the
information
and
images
that
could
be
resolved through radar
systems.
Smaller

beam
widths
facilitated greater
accuracy.
In
tum,
the
smaller,
more
accurate
radar technologies
greatly
in-
creased
the
number
and
types
of
applications that
were
practical,
making
it
possible
to
mount
radars
on
boats

and
planes.
See
magnetron.
CD
radio
See
citizen's band
radio.
CDC
See
Canadian Broadcasting
Corporation.
CDDS
1.
Common Basic Data Set.
2.
See
Con-
nectionless Broadband Data
Service.
CDEMA Computer
and
Business
Equipment
Manu-
facturers
Association.
See
Information

Technology
Industry
Council.
CDRAnATM
traffic
flow
control
concept.
See
con-
stant bit
rate.
CDS
See
Columbia
Broadcasting
System.
CDSC
See
Canadian
Broadcast Standards
Council.
CDT
1.
See
Canadian
Business
TelecommUnications
Alliance.
2.

Computer-Based Training.
See
com-
puter-assisted instruction.
CDTA
See
Canadian
Business
Telecommunications
Alliance.
CDX
Computerized Branch
Exchange.
A
commer-
cial
private telecommunications
system
trademarked
by
the
ROLM
Corporation
as
their version ofa pri-
vate
branch
telephone
exchange
(PBX).

CDYD
Call
Before
You
Dig.
The
warning
on
signs
by
fiber
optic
cables
to
prevent contractors
and
other
diggers
from
damaging
underground installations.
CCD
See
Common
Carrier
Bureau.
CCC
1.
clear
channel

capability.
In
communications,
that
portion ofa
data
transmissions capacity
that
is
available
to
users,
the
informational portion,
above
and
beyond
the
various
control
and
signaling
trans-
missions
associated
with
the
functioning
of
the

tech-
nology.
2.
Communications Competition
Coalition.
A
Canadian
support
and
lobbying
organization
estab-
lished
to
encourage Canadian telecommunications
competition.
3.
Center
for
Corporate
Communica-
tions.
/>puter Communications
Club.
/>CCD
1.
See
charge coupled
device.
CCI

See
co-channel interference.
CCIA
See
Computer
and
Communications Industry
Association.
CCIR
1.
See
Centre
for
Communication Interface
Research.
2.
See
Comite
ConsultatifIntemational
des
Radiocommunications.
CCIR
video
standard
Similar
to
the
EIA
RS-170a
standard

for
color
video,
CCIR
is
a
dominant
video
format
used
in
Europe
just
as
NTSC
is
standardized
in
North
America
and
Japan.
CCIR
supports
a verti-
cal
resolution of625
scanlines,
575
of

which
are
typi-
cally
displayed.
It
is
an
interlaced
format
with
two
scans
of
the
screen
combining
to
create a conceptual
frame.
The
number oflines per
field
(two
of
which
make
up
the
frame)

is
282.5
compared
to
242.5
for
RS-170a.
The
effective resolution
when
conversion
167
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
with
raster-based displays
is
desired
is
768
(compared
to 640 for RS-170a). CCIR video
is
traditionally
transmitted
over
75-ohm

well-shieldedcoaxial
cables.
CCIRN Coordinating Committee
for
Intercontinen-
tal Research Networks. Established by
the
U.S. Fed-
eral Networking Council (FNC)
and
the European
Reseaux Associees pour la Recherche Europeenne
(RARE).
CCIRN
promotes international cooperation
and sponsors a number
of
working groups that meet
in
different parts
of
the world.
CCIS
See
Common
Channel Interoffice Signaling.
CCITT
Comite Consultatif Internationale de
Telegraphique
etTelephonique.

International
Telegraph
and
Telephone
Consultative Committee. An influen-
tial United Nations-sponsored international telecom-
munications standards committee based in Geneva,
Switzerland. It changed
its
name
to
lTU
in
1990.
See
International Telecommunication Union.
CCITT Study Groups These subgroups, operating
under
the
CCITT (now the lTD) study and make rec-
ommendations
for
specialized areas
of
telecommu-
nications. See International Telecommunication
Union.
CCNR(telephone) call completion
on
no

reply (e.g.,
as
in
ISDN Q.733 call completion services).
CCP
See Compression Control Protocol.
CCR
See
current cell rate.
CCS See Common Channel Signaling.
CCS/SS7 Common Channel SignaVSignaling Sys-
tem
7.
See
Signaling System
7.
CCSN Common Channel Signaling Network. See
Common Channel Signaling.
CCT
1.
Calling Card Table. See unmatched call.
2.
See
Consultative Committee Telecommunications.
Common
CD
Formats
Format Description
CD-Audio
Compact

disc
audio.
A
digital
sound
representation
standard
that
is
incorporated
into
CD-
ROMs.
Conversion
from
digital
to
analog
for
listening
occurs
in
the
computing
hardware.
Also
known
as
Redbook
Audio.

CD-I
Compact
disc
interactive.
An
interactive
multimedia
standard
developed
by
Philips
and
Sony.
CD-I
players
are
designed
to
accept
and
playa
variety
of
CD-encoded
data
and
can
typically
be
interconnected

with
a
computer
or
TV
playback
system.
CD-Plus
Compact
disc
plus.
A
standard
developed
by
Philips
and
Sony
that
enables
audio
CD
players
to
play
multimedia
(graphics
and
sound)
discs

by
skipping
over
the
nonaudio
segment
that
is
stored
on
the
frrst
track.
CD-R,
CD-ROM
R
Compact
disc
recordable.
A
format
for
read/write
CD-ROM
systems.
See
compact
disc
for
a

fuller
description.
CD-ROM
Compact
disc
read
only
memory.
A
standardized,
widely
used
format
for
storing
digital
information
on
small
flat
optical
platters
that
are
read
with
laser
technology
and
played

on
CD
players.
See
compact
disc
for
a
fuller
description.
CD-ROM
A
computer
peripheral
that
reads,
and
sometimes
writes,
digital
information
to
a
compact
disc.
Most
consumer
CD-ROM
drives
are

read
only,
although
read/write
drives
are
now
under
$300
and
may
soon
be
a
consumer
item.
A
CD-ROM
drive
can
be
used
to
run
applications,
read
text
files,
images
(PhotoCD),

and
audio.
Many
CD-ROM
drives
come
with
software
to
play
audio
CDs
through
a
speaker.
CD-ROM
X
A
compact
disc
read
only
memory
extended
architecture.
A
fonnat
developed
by
Microsoft

that
enables
the
interleaving
of
audio
and
video,
rather
than
recording
them
on
separate
tracks.
It
requires
a
player
that
can
understand
the
format.
If
played
on
a
regular
player,

the
audio
will
not
be
detected
and
played.
CD-RW
CD
recordable/rewritable
technologies
that
became
prevalent
in
the
late
1990s
and
which
were
almost
immediately
challenged
by
emerging
DVD
technologies.
CD-UDF

A
standardized
fonnat
for
CD-recordable
(CD-R)
media
that
enables
a
variable
packet-
writing
scheme
to
be
used
as
an
incremental
approach
to
the
recording
of
compact
discs
(CDs).
It
provides

a
means
for
easily
recording
files
on
a
CD
in
much
the
same
manner
as
on
a
floppy
disk.
CD-V
Compact
disc
video.
A
standard
for
storing
video
images
on

compact
discs
that
hasn't
really
caught
on.
It
is
being
superseded
by
CD-XA
which
enables
the
interleaving
of
video
and
sound.
CD-WO
Compact
disc
write
once.
A
fonnat
designed
for

mastering
a
CD.
The
CD
is
then
used
in-
house
or
in
limited
quantities,
or
is
sent
to
a
duplication
factory
for
mass
production.
Drives
that
are
able
to
write

a
master
CD
were
once
out
of
the
price
range
of
small
companies
and
consumers,
but
they
have
dropped
to
below
$300
and
can
now
be
used
by
software
developers,

composers,
and
small
record
companies
to
produce
masters
or
small
production
runs
of
specialized
recordings.
168
© 2003 by CRC Press LLC
CCTA
See
Central
Computer
and
Telecommunica-
tions
Agency.
CCTV
Closed
Circuit
TV.
See

closed
circuit
broadcast.
CCU
1.
camera control unit.
2.
communications
control
unit.
CD
1.
See
carrier
detect.
2.
See
compact
disc.
See
Common
CD
Formats
chart.3. count
down.
A
con-
cept
in
broadcasting

related
to
the
signaling
of
the
be-
ginning
of
taping,
editing,
or
live broadcasting.
CDA
See
Communications
Decency
Act.
CDCS
Continuous
Dynamic
Channel
Selection.
CDDI
See
Copper
Distributed
Data
Interface.
CDE

See
Common
Desktop
Environment.
CDF
See
cutoffdecrease
factor.
CDLC
See
Cellular Data Link
Control.
CDMA
See
code
division multiple
access.
CDMP Cellular Digital
Messaging
Protocol.
CDO
See
community
dial
office.
CDP
1.
Cisco
Discovery Protocol.
2.

Customized
Dial
Plan.
CDPD
See
Cellular Digital Packet
Data.
CDPD
Forum,
Inc. A not-for-profit organization
established
in
1994
to
promote
the
development
and
acceptance
ofCellular Digital Packet Data
(CDPD).
It
supports
vendors
who
develop
and
distribute
CDPD
products

and
services.
/>CDR
See
Call
Detail
Record.
CDRH classifications A series ofclassifications
to
alert
users
of
the
dangers
of
incorrect
use
of laser-
based
components
that
emit
external
beams
(more
powerful
lasers
may
be
inside

the
assembly
but
must
not
emit
to
the
exterior of
the
device).
The
laser
safety
classification categories
are
somewhat generalized
since
the
wavelength
of
the
light
is
an
additional
fac-
tor controlling
the
influence of

the
beam
and
is
not
specified
for
all
categories.
CDT
credit
allocation.
In
packet-switched
networks,
such
as
OSI,
CDT
applies
to
transmission
flow
control.
CDTAC
See
Consumer/Disabilities
Telecommuni-
cations
Advisory

Committee.
CDV
1.
cell delay variation.
2.
See Compressed
Digital
Video.
CDVT
See
cell
delay
variation
tolerance.
CE
Connection
endpoint.
1.
In
ATM
networking,
a
terminator
at
one
end
ofa layer connection within a
SAP.
2.
circuit emulation.

CE
Mark
A sign
that
an
object
has
been
certified
through
the
overseeing
European
regulatory
body,
the
European Telecom Directive, and does
not
require
further
testing
or
approval
within
the
individual
par-
ticipating
countries.
The

mark
provides
identification
ofproducts that
conform
to
certain specified
safety,
electromagnetic,
and
interoperability
requirements.
CE
certification
is
required
for
all
telecommunica-
tions
terminal
equipment
(TTE)
sold
in
the
European
Union.
See
Underwriters Laboratory,

Inc.
CEBus ConsumerElectronics
Bus.
A
home
automa-
tion
standard
managed
by
the
CEBus
Industry
Coun-
cil
and
accepted
by
the
Electronics Industry
Associa-
tion
(EIA).
CEBus
specifies a
common
format
for
connectionless peer-to-peer communications over
standard electrical wiring. The

CEBus
HomePnP
standard
is
anonproprietary protocol
based
upon
the
lEA
600
open
standard.
In
terms
of
functionality,
it
is
similar
in
concept
to
the
X-I0 protocol
in
that it
operates over
120-volt,
60-cycle
home

wiring.
CEBus
is
a
two-channel
specification,
with
one
chan-
nel
assigned
to
realtime control
functions,
the
other
to
informational
data.
It
uses
a
CSMA/CD
protocol
that includes various error detection
and
retry
func-
tions,
end-to-end acknowledgment,

and
authentica-
tion.
The
Powerline Carrier uses spread spectrum
technology
to
bypass
electrical
impediments
in
home
wiring,
spreading
the
signal over arange of
frequen-
cies
rather
than
using
a single
frequency.
See
spread
spectrum,
X-IO.
CEBus
Industry
Council

CIC.
A users
group
sup-
porting the development
and
use
of
interoperable
CEBus-based
home
network automation technolo-
gies.
/>CEDAR
The
Center
of
Excellence
for
Document
Analysis
and
Recognition.
An
organization
at
the
CDRH
Laser
Safety Classification Categories

Class
Designation
Notes
Class
I
EXEMPT
Visible,
low-powered
lasers considered
safe
for
viewing.
Class
II
CAUTION
Visible
lasers
in
the
600
to
700
nm
range
at
1
mW
or
less.
Do

not
stare
directly
at
the
beam
or
a reflection of
the
beam.
Class
lila
DANGER
Visible
lasers
in
the
600
to
700
nm
range
at
5
mW
or
less.
Severe
eye
damage;

avoid
eye
exposure
to
the
beam
or
areflection of
the
beam.
Class
IIIb
DANGER
Visible
lasers
in
the
600
to
700
nm
range
at
5
mW
or
greater
and
invis-
ible

lasers
in
the
700
to
900
nm
range.
Severe
eye
damage;
avoid
any
exposure
to
the
beam
or
reflection of
the
beam.
Doesn't present
fire
haz-
ard.
Class
IV
DANGER
High
power lasers exceeding characteristics

of
Class III lasers. They
present avariety of
dangers
from
eye
and
object
damage
to
diffusion
haz-
ards,
burns,
and
general
fire
hazards.
169
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
State
University
of
New
York
at

Buffalo
that
provides
a
number
ofinteresting services
including
informa-
tional
CD-ROMs.
CEI
In
ATM
networking, a connection endpoint
identifier.
Celestri A
downsized
version of
the
original M-star
project,
Celestri
is
a
low
Earth
orbit
(LEO),
geosta-
tionary

hybrid
satellite
system
from
Motorola.
In
May
1998,
the
Celestri
expertise
and
technology
was
rolled
into
the
Teledesic
project,
when
Motorola
Inc.
bought
in
as
a
major
partner.
See
Teledesic.

cell,
ATM
In
asynchronous transfer
mode
network-
ing,
a
unit
oftransmission consisting ofa fixed-size
frame
comprising
a
header
and
a
payload.
See
asyn-
chronous
transfer
method,
cell
rate.
cell, battery
Minimally,
a receptacle containing
an
electrolyte
and

two
electrodes
arranged
so
the
elec-
tricity
can
be
generated
from
the
cell
by
chemical
actions.
Development
of
modem
cells
stems
from
the
experiments of
C.A.
Volta.
Two
or
more
cells

can
be
combined
to
form
abattery.
See
battery,
storage
cell.
cell,
mobile phone
In
mobile communications,
the
basic
geographic
unit
ofa distributed broadcast
sys-
tem,
within
which
a
low-power
transmitting station
is
located.
Roughly
hexagonal

in
shape,
depending
upon
terrain.
Its
size
varies
with
available channels,
generally increasing
as
the
radius
of
each
cell
de-
creases.
Cells
are
further
grouped
into
clusters.
See
cluster,
cellular
phone,
mobile

phone.
cell
delay variation
CDY.In
AIM
networking,
a
traf-
fic
flow
buffering
and
scheduling
concept.
CDV
pa-
rameters
are
associated
with
constant
bit
rate
(CBR)
and
variable
bit
rate
(VBR)
services

and
relate
qual-
ity
of service
(QoS)
information
by
indicating
the
probability
that
a
cell
may
arrive
late.
See
cell
rate.
cell
delay variation tolerance
CDVT.
In
ATM
net-
works,
a
traffic
flow

control
mechanism
that
allows
cells
to
be
queued
during
multiplexing
to
allow
oth-
ers
that
are
being
moved
onto
the
same
communica-
tions
path
to
be
inserted.
Cells
may
also

be
queued
to
allow
time
for
the
system
to
insert
control
cells
of
one
sort
or
another.
See
cell
rate.
cell error ratio
In
ATM
networks,
the
ratio of
cells
in
a transmission
that

are
errored
to
the
total
cells
in
the
transmission,
over
aspecified
time
interval,
pref-
erably
as
measured
on
an
in-service circuit.
See
cell
loss
ratio,
cell
rate.
cell
interarrival variation
CIY.
In

ATM
networks,
a
description
of
changes
in
arrival
times
of
cells
near-
ing
the
receiver.
If
the
cells
are
carrying
information
in
which
the
arrival
of
the
cells
at
the

same
time
is
important
to
the
synchronization of
the
final
output,
as
in
constant
bit
rate
(CBR)
traffic,
then
latency
and
other
delays
that
cause
interarrival variation
can
in-
terfere
with
the

output.
For
example,
in
videoconfer-
encing,
synchronization of
images
and
sound
might
be
affected
by
cell
delays.
See
cell
rate,
cell
delay
variation
tolerance,
jitter.
cell
loss
priority
field
CLP.
In

ATM
networks,
a
bit
field
contained
in
the
header
cell
that
indicates
the
cell
discard
eligibility of
the
cell.
In
congested situa-
tions,
this
cell
may
be
expendable.
170
cell
loss
ratio

CLR.
In
ATM
networks,
cell
traffic
is
handled
in
many
ways
in
order
to
maximize
through-
put,
to
synchronize arrival
times
where
appropriate,
and
to
minimize
delays,
latency,jitter,
or
loss.
The

cell
loss
ratio
is
a
negotiated
quality
of
service
(QoS)
param-
eter
that
depends
upon
the
network
traffic
flow
con-
trol
setups.
It
is
computed
as
a ratio of
lost
cells
to

the
number
of
total
cells
transmitted,
expressed
as
an
order
ofmagnitude.
See
cell
error ratio,
cell
loss
pri-
ority
field,
cell
rate,
leaky
bucket.
cell
misinsertion rate
CMR.
In
AIM networking, a
traffic
flow

evaluation parameter giving
the
ratio of
cells
that
are
received
at
the
endpoint,
that
were
not
originally transmitted
by
the
source,
compared
to
the
total
number
ofcells correctly transmitted.
cell
phone
See
cellular
phone.
cell
rate

In
ATM
networks, a concept
that
expresses
the
flow
of basic
units
of transport
used
to
convey
data,
signals,
and
priorities.
See
the
Cell
Rate
Con-
cepts
chart
for
further detail.
See
leaky
bucket,
cell

rate
margin.
cell
rate margin
CRM.
In
ATM
networks,
an
expres-
sion
of
the
difference between
the
effective
band-
width
allocation
for
the
transmission
and
the
sustain-
able
cell
rate
allocation
in

cells
per
second.
cell
relay A
type
of
fast
packet switching network
architecture
using
small
fixed
length
packets
that
can
be
used
for
avariety of
data
types.
The
cell
format
is
typically
53
octets comprised of 5

bytes
of
address
information
and
48
bytes
ofinformational
data.
Cell
relays
can
also
provide
quality ofservice
(QoS)
guar-
antees
to
a
variety
of
services.
See
Frame
Relay.
cell
relay function
In
ATM

networking, a
basic
ser-
vice
provided
to
ATM
endstations.
See
cell
relay.
cell
relay service
CRS.
An
ATM
carrier
service.
cell
reversal
In
a
battery,
a
reversal
of
the
polarity of
the
terminal

cells
resulting
from
discharge.
cell
site
In
cellular
wireless
communications
systems,
an
individual
transceiving
unit.
Multiple
cell
sites
pro-
vide
roaming capabilities.
The
cell
site
serves
the
lo-
cal
cell
and

slightly
overlaps
with
adjoining cells
to
minimize
dead
spaces
between
transmissions
when
a subscriber passes
from
one
cell
region
to
another.
cell
site controller Cellular
radio
operates
with
nu-
merous
cells,
each
associated
with
a

transceiver.
The
cell
site
controller
manages
the
various
radio
chan-
nels
within that cell, allocating
them
when
a user
moves
into
range of
the
cell,
and
deallocating
and
re-
using
available frequencies
as
the
user
moves

out
of
range
again,
or
terminates
the
connection.
cell
splitting A
means
ofincreasing
the
call
capacity
ofa
cellular
system
by
splitting
cells
into
smaller
units.
cell
switch router
CSR.
A
network
routing

device
that
incorporates
ATM
cell
switching
in
addition
to
conventionalLP
datagram
forwarding,
in
order
to
pro-
vide
improved
service over traditional hop-by-hop
datagram
forwarding,
especially
with
transmissions
that pass through subnetwork boundaries. See
RFC
2098.
cell switching
In
cellular

mobile
phone
systems,
the
overall
process ofhandling calls, monitoring signals
as
users
move
in
and
out
of
range
of
the
transceivers
© 2003 by CRC Press LLC
in
the
various
cells,
and
allocating
and
deallocating
frequencies
as
needed
to

provide seamless service
through a series
of
cells. Cells are
designed
to
over-
lap
somewhat
so
that
there
is
no
gap
when switching
from
one
to
another
and
to
compensate
for
the
fact
that
the
signal
is

weakest
on
the
periphery
of
the
trans-
mitting
area.
The
sophisticated moment-by-moment
monitoring and orchestrating
of
this process
is
handled by monitoring systems
and
cell-switching
software.
cell transfer
In
cellular mobile
phone
systems,
the
logistics of
keeping
an
ongoing connection
at

accept-
able
volume
and
quality levels
when
switching
the
user
from
the
transceiver
in
one
cell
to
the
transceiver
of
the
cell
that
is
being
entered.
This
transfer
involves
allocating a
frequency

channel
in
the
entered
cell
and
deallocating
and
reassigning,
if
needed,
the
frequency
channel of
the
exited cell.
cell transfer delay
CTD.
In
ATM
networking,
the
time
elapsed
between
a
cell
exit
event
at

the
first
point
of
measurement and the corresponding cell entry
event
at
the
second point
of
measurement
for
a par-
ticular connection.
The
cell transfer
delay
between
the
two
points
of
measurement
is
the
sum
of
the
total
inter-ATM

node
transmission
delay
and
the
total
ATM
node
processing
delay.
See
cell rate.
CelloAgraphical
Web
browser created
at
the
Cornell
Legal Information Institute.
cellphone
See
cellular phone.
cells in flight
CIF.
In
ATM
networking, a descrip-
tive phrase
for
a traffic service parameter,

the
avail-
able
bit rate
(ABR).
CIF
is
a cell number
limit
nego-
tiated between
the
receiving network
and
the
source
of
the
cells during
the
idle startup period, prior
to
the
fIrst
RM-cell returns.
See
cell rate,
Cells
in
Frames.

Cells in Frames
CIF.
The
name
given
to
a number
of
mechanisms for carrying
ATM
network traffic
across
a media segment and network interface
card.
CIF
was
developed
by
the
Cells
in
Frames
Alliance,
a
diverse
group
ofprofessionals
and
commercial
ven-

dors.
This
group
released the
fIrst
CIF
sp~cification
in
1996
for
carrying
ATM
over
Ethernet,
Token-Ring,
Cell
Rate
Concepts
in
ATM
Networks
Abbreviation/Function Descriptor
Notes
ACR
allowed
cell
rate
A
traffic
management

parameter
dynamically
managed
by
congestion
control
mechanisms.
ACR
varies
between
the
minimum
cell
rate
(MCR)
and
the
peak
cell
rate
(PCR).
CCR
current
cell
rate
Aids
in
the
calculation of
ER

and
may
not
be
changed
by
the
network
elements
(NEs).
CCR
is
set
by
the
source
to
the
available
cell
rate
(ACR)
when
generating a
forward
RM-cell.
COP
cutoff
decrease
factor

Controls
the
decrease
in
the
allowed
cell
rate
(ACR)
associated
with
the
cell
rate
margin
(CRM).
CN
cell
interarrival
variation
Changes
in
arrival
times
of
cells
nearing
the
receiver.
If

the
cells
are
carrying
information
that
must
be
synchronized,
as
in
constant
bit
rate
(CBR)
traffic,
then
latency
and
other
delays
that
cause
interarrival variation
can
interfere
with
the
output.
GCRA

generic
cell
rate
algorithm
A
conformance
enforcing
algorithm
that
evaluates
arriving
cells.
See
leaky
bucket.
ICR
initial
cell
rate
A
traffic
flow
available
bit
rate
(ABR)
service
parameter.
The
ICR

is
the
rate
at
which
the
source
should
be
sending
the
data.
MCR
minimum
cell
rate
Available
bit
rate
(ABR)
service traffic
descriptor.
The
MCR
is
the
transmission
rate
in
cells

per
second
at
which
the
source
may
always
send.
PCR
peak
cell
rate
The
PCR
is
the
transmission
rate
in
cells
per
second
that
may
never
be
exceeded,
which
characterizes

the
constant
bit
rate
(CBR).
RDF
rate
decrease
factor
An
available
bit
rate
(ABR)
flow
control
service
parameter
that
controls
the
decrease
in
the
transmission
rate
of
cells
when
it

is
needed.
See
cell
rate.
SCR
sustainable
cell
rate
The
upper
measure
ofa
computed
average
rate
of
cell
transmission
over
time.
UBR
unspecified bit
rate
An
unguaranteed
service
type
in
which

the
network
makes
a
best
efforts
attempt
to
meet
bandwidth
requirements.
VBR
variable
bit
rate
The
type
ofirregular traffic generated
by
most
nonvoice
media.
Guaranteed
sufficient
bandwidth
and
QoS.
171
© 2003 by CRC Press LLC