Fiber Optics Illustrated Dictionary - Part 20 doc

Fiber
Optics
Illustrated
Dictionary
circuit switching A
type
ofend-to-end transmission
system
common
in
phone
connections.
In
the
process
of setting
up
the
connection, a
number
ofresources
are
allocated
to
that
specific
call,
most
of
which
are

tied
up
until
the
call
is
completed
and
the
connection
terminated.
One
advantage
of
this
system
is
that
it
can
guarantee a
certain
level
of
performance.
A
disadvan-
tage
is
that

the
resources
are
tied
up
whether
or
not
there
is
active
communication.
See
message
switch-
ing,
packet
switching.
circular antennaA
horizontally
polarized,
half-wave
dipole
antenna
formed
into
the
shape
ofa circle
ex-

cept
that
the
terminating
ends
do
not
touch
to
make
a
continuous
loop.
circular magnetic
wave
A
magnetic
wave
in
which
the
lines
offorce describe acircular
pattern.
circular polarization
An
electromagnetic wave
whose
lines
of

flux
are
oriented
in
a
plane,
usually
horizontal
or
vertical,
or
where
the
"edge" of
the
field
describes a circular
shape.
Circular polarization
is
used
in
antennas, where electricity serves
to
uni-
formly
rotate
the
electromagnetic
field

through
the
antenna.
It
is
possible
to
use
one
circularly polarized
wave
to
communicate
with
another,
or
the
circularly
polarized
wave
can
be
manipulated
to
yield linearly
polarized
waves
perpendicular
to
one

another.
circular scanning
Scanning
in
which
the
sweep
of
the
sensor
and/or
the
display
monitor describes a
full
360
0
arc,
which
can
be
pictured
as
a cone shape
spreading
out
toward
the
direction of
the

region
be-
ing
scanned
(e.g.,
some
types
of
radar).
circulator
I.
A
process
or
device that
moves
some-
thing
from
hand
to
hand,
or
device
to
device.
2.
In
microwave
transmissions, a multiterminal coupling

device
in
which
the
transmission
is
passed
down
through
adjacent
terminals.
3.
In
radar
transmissions,
a
device
that
alternates
the
signal
between
the
trans-
mitter
and
the
receiver.
4.
In

data
communications, a
mechanism
for
allocating
or
transferring information
or
control
among
ports.
CISC
See
Complex
Instruction
Set
Computing.
CISCC Collocation Interconnection Service
Cross
Connection.
Cisco
lOS
Cisco
Internetwork
Operating
System.
An
OS
incorporated
as

part
of
the
CiscoFusion architec-
ture
to
help
the
system
administrator centralize,
in-
tegrate,
install,
and
manage
internetworks.
Cisco Systems Inc. Asignificant vendor of
routers,
switchers,
and
related
hardware
and
software
for
net-
work
systems.
The
author gained a greater under-

standing
of
the
function
and
implementation of
net-
work
routing
systems
through
Cisco
seminars.
CiscoFusion A
Cisco
Systems
intemetworking
archi-
tecture
that
integrates
scalable,
stable,
secure
tech-
nologies
with
ATM,
local
area

networks
(LAN),
and
virtual
local
area
networks
(VLANs).
Cisco
View
A
graphical
device-management
applica-
tion
that
dynamically
provides
administrative,
moni-
toring,
and
configuration
information
for
Cisco
inter-
network
devices.
CISE

See
Computer
and
Information Science
and
Engineering.
182
CISPR
See
International Special
Committee
on
Ra-
dio
Interference.
CITA
See
Canadian
Independent
TelephoneAssociation.
CITEL Inter-American Telecommunications
Com-
mission.
citizens band radio, citizens radio service
CB
ra-
dio.
Radio
frequencies
set

aside
for
the
use
of
rela-
tively
low
power consumer radios
and
radio
control-
lers
(for
model
cars
and
planes).
These
have
a
lim-
ited
range
(up
to
about
10
or
15

miles
for
mobile
units), although sunspot activity
and
local
weather
can
sometimes provide
some
surprisingly
long
con-
nections
when
broadcasting conditions
are
optimal.
In
the
United
States,
CB
radios
are
commonly
used
by
truckers,
travellers,

and
radio
hobbyists.
Commu-
nications over
150
miles
are
prohibited
by
the
Fed-
eral
Communications
Commission
(FCC).
The
fre-
quencies
originally
allocated
by
the
FCC
were
around
27
Mhz,
but
have

been
changed
to
around
463
to
470
MHz.
Before computer bulletin
board
systems
and
the
Internet,
CB
radio
was
a popular
means
of
com-
munity
interaction.
Not
all
countries
are
free,
and
ci-

vilian
use
ofradios
is
not
permitted
in
some
regions
of
the
world.
See
OSCAR,
AMSAT.
CITR Canadian Institute
for
Telecommunications
Research.
CITRIS See Information Technology Research
Center.
CITU
See
Central
IT
Unit.
City and Suburban Telegraph Company
The
first
company

in
Cincinnati,
OR
to
provide
direct
com-
munication
between
homes
and
businesses, incorpo-
rated
in
1873.
In
1878,
it
contracted
with
the
Bell
Telephone
Company
of
Boston,
MA
to
provide
Bell

services
in
the
Queen
City
area
and,
in
1882,
con-
tracted
with
American
Bell
to provide long-distance
services.
Its
first
payphone
was
installed
in
1904
and
mobile
phones
were introduced
in
1946.
In

1952,
it
became
the
first Bell company
to
provide
100%
dial
service.
The
company
became
Cincinnati
Bell
Tele-
phone
in
1971.
CIV
See
cell
interarrival variation.
CIVDL
See
Collaboration
for
Interactive
Visual
Dis-

tance
Learning.
CIX
See
Commercial
Internet
Exchange.
CJC
See
Canadian
Journal
of
Communication.
CKAC
The
first Canadian television broadcasting
station,
which
began
experimenting
with
mechani-
cal
television transmitted
over
wires
in
1926.
ABaird
disc

camera
and
Jenkins
scanning
disc
television
re-
ceiver
were
early inventions
that
were
tried
around
this
time.
Sound
and
images
were
transmitted
sepa-
rately
so
the
sound
could
be
played
on

a
radio
re-
ceiver.
Shortwave
bands
were
used
for
the
images.
Alphonse
Ouimet,
who
later
became
the
president of
the
CBC,
was
a
technician
for
the
first
historic
CKAC
broadcast
in

1931,
a
musical
performance
that
was
sent
out
to
20
viewers.
See
Canadian
Broadcasting
Corporation.
CL
symb.
left-hand circular
or
indirect polarization.
cladding
I.
A
coating,
something
that
overlays,
a
pro-
tective covering, sheath.

2.
A substance, such
as
© 2003 by CRC Press LLC
metal,
bonded
to
another
to
cover
it
by
various
means,
such
as
pressure
rolling
or
extruding.
A
process
some-
times
used
in
producing
transmission
cables.
3.

A
layer
in
a
laminate
(which
may
be
planar
or
spheri-
cal)
with
a
lower
refractive
index
than
its
associative
conductive
materials,
as
in
a
fiber
optic
transmission
cable,
such

that
incident
light
is
reflected
away
from
the
cladding
rather
than
passing
through.
Glass
and
plastics
are
commonly
used
as
fiber
cladding
mate-
rials
but
planar
laminates
may
use
other

materials
as
well.
Depending
upon
the
materials
and
their
refrac-
tive
indexes,
there
are
effective
ratios
between
a
clad-
ding
layer
(as
in
a
fiber
bundle)
and
an
inner
conduct-

ing
core
as
well
as
limits
established
by
economics
and
whether
the
cable
needs
to
be
flexible.
Different
cladding
arrangements
have
some
interesting
effects
on
light
transmission
in
a
fiber

cable.
For
example,
the
materials
in
the
cladding
may
be
designed
to
re-
flect
some
wavelengths
and
absorb
or
transmit
oth-
ers.
The
cladding
may
also
be
designed
so
that

it
be-
comes
thin
at
certain
bend
radiuses
to
emit
rather
than
reflect light
(thus
radiating
modes
exceed guided
modes).
This
may
seem
impractical,
but
it
allows
the
fabrication
of
illuminated
"fabric"

sheets
by
weaving
the
fibers
over
a
warp
layer
that
deliberately
bends
the
fiber
filament
at
periodic
intervals.
See
index
of
refraction,
spilling,
stray
light,
total
internal
reflec-
tance,
V

number.
cladding alignment splicer
CAS.
A
precision
indus-
trial
tool
for
preparing
a
variety
of
types
of
cladded
fibers
(single-mode,
multimode,
dispersion-shifted,
etc.)
for
assembly
and
installation.
The
device
pro-
vides
a

tension
and
alignment
mechanism
(e.g., a
groove)
to
facilitate
precise
splicing
of
cleaved
fiber
filaments.
It
may
optionally
have
fiber
end
angle
measurement,
defect
detection
and
pigtail
continu-
ity
assessment
capabilities.

Passive
alignment
sys-
tems
(
on
two
axes)
provide
cladding
alignment
rather
than
core-to-core
alignment.
A
CAS
typically
uses
heat
(fusion
splicing)
to
join
fiber
filaments
into
a
continuous
waveguide.

Automatic
units
can
create
a
splice
in
about
10
to
20
seconds
(not
including a
technician's
assessment
of
the
visual
display
of
the
splice
and
its
accompanying
data
parameters).
A
CAS

typically
includes
a
small
built-in
display
or
a
connection
to
a
computer
display
to
provide
an
im-
age
of
the
assembly
and
alignment
in
the
X
and
Y
coordinates,
usually

magnified
about
100
times.
This
enables
a
technician
to
visually
inspect
the
assembly.
Since
there
are
many
different
splice
modes,
depend-
ing
upon
the
type
of
fiber
and
components,
the

unit
may
be
preprogrammed
or
programmable
for
quick
setup.
Depending
upon
the
splicing capabilities,
it
may
be
possible
to
store
and
retrieve
a
log
of
splic-
ing
activities,
including
the
selected

splice
modes,
arc
conditions,
estimated
efficiency
(e.g.,
loss
estimates),
and
optional
comments.
Stand-alone
units
may
log
from
ca.
300
to
1000
splices.
Units
with
computer
connections
could
provide
unlimited
logging

with
re-
movable
mass
storage,
which
may
aid
companies
in
monitoring
quality
control,
production
changes,
staff
training
statistics,
etc.
See
cleave,
fusion
splice.
cladding diameter
In
a
cable
that
includes
a

clad-
ding layer, such
as
a metal wire with a bonded
coating,
or
a
two-glass
cladded
fiber
cable,
the
di-
ameter
that
includes
the
cladding
layer.
Ina
perfectly
round
fiber,
this
can
simply
be
measured;
however,
as

the
cable
may
be
elliptical,
the
diameter
may
be
calculated
by
taking
the
average
of
the
smallest
cir-
cular
outer
diameter
and
the
largest
circular
inner
di-
ameter.
Cladding &
Core

Ratios
in
Optical
Cables
A_~-=-
B
G~~_:·_··
_
In single-modefibers
(A),
the cladding thickness
(1)
is typically much larger than the diameter
of
the tiny
filament thatforms the core
(2).
In multimodefibers,
the relationship is typically reversed. The core has a
higher diameter in relation to the cladding thickness,
providing room
for
multiple wavelengths
to
travel
along the waveguide.
The ideal ratio depends upon manyfactors, includ-
ing the cable materials, the wavelengths transmitted,
and the degree
of

bend that might
be
expected
of
the
cable during installation.
cladding glass A
type
of
glass
or
other
transparent
material
used
in
fiber
optic
cables
that
has
a
lower
refractive
index
than
the
glass
used
in

the
inner
core.
cladding mode
In
a
transmission
through
a
cladded
conductor,
a
signal
conducted
through
the
outer
clad-
ding
in
addition
to
any
signals
that
may
be
transmit-
ted
through

the
cladded
core.
See
cladding
beam.
clamping
1.
Holding
within
an
established
operat-
ing,
baseline,
or
midline
range
in
a
circuit,
in
order
to
maintain
various
processes
or
electrical
charges

at
stable
or
safe
levels.
2.
In
a
cathode-ray
tube
(CRT),
a
process
that
establishes
a
level
for
the
picture
dis-
play
at
the
beginning
of
each
scan
line
within

a
frame.
clamping voltage An established
level
of
voltage
around,
under,
or
over
which
an
electrical
device
is
pennitted
to
operate.
For
example,
clamping
voltages
can
be
used
to
establish
a
range
within

which
a
de-
vice
operates,
by
setting
them
so
that
any
fluctuations
above
or
below
that
voltage
will
cause
a
system
shut-
down
or
other
protective
reactions.
Clark
cell A
type

of
historic
low-volt
energy
cell
us-
ing
mercury
and
zinc
amalgam
in
the
cathodes
and
anodes.
Clark, David
(ca.
1943- )
David
Clark
has
been
a
chairman
and
active
participant
in
various

Internet
as-
sociations,
including
the
IRTF
and
lAB.
He
has
par-
ticipated
in
numerous
research
efforts
in
high
speed,
very
large
networks,
and
network
video
applications,
and
various
development
efforts

including
the
Swift
183
.?:'
;,

:::~.~.,.F

.z~
-,tt
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
operating
system,
Multics
and
Token-Ring
local
area
networks
(LANs).
Clark, James
"Jim"
H. (1944- )
Formerly
ofSGI,

in
1994
Clark
co-founded
Mosaic
Communications
Corporation
with
Mark
Andreessen,
which
later
be-
come
Netscape
Communications,
distributors of
the
most
broadly
used
browser
applications
on
the
World
Wide
Web.
See
World

Wide
Web.
Clarke,
Arthur
C. (1917- )
An
English-born
scien-
tist
and
writer.
With
remarkable
prescience,
Clarke
anticipated
the
age
of satellites
and
long-distance
communications.
He
was
talking
about
it
as
early
as

1942,
while
still
in
his
twenties,
and
published
an
ar-
ticle about
it
called "Extra-Terrestrial Relays"
in
Wireless
World
in
1945.
Clarke
further
wrote
detailed
descriptions
of
geostationary
satellite
orbits
and
sat-
ellite

transmitting
and
receiving
stations
in
the
1950s,
years
before
the
first
Sputnik
was
launched.
In
the
1960s,
he
collaborated
with
Stanley
Kubrick
in
the
making
of
the
movie
2001:
A

Space
Odyssey
(1968),
which
has
since become a classic.
See
satellite,
Sputnik
I.
Clark, George Howard (1881-1956) A
Canadian-
born
American
telegraph
operator
and
significant
col-
lector
of
historical
radio
artifacts,
Clark
worked
for
the
Boston
and

Maine
Railroad.
A
scrapbook
enthu-
siast
as
a
child,
Clark
began
collecting
wireless
ra-
dio
materials
in
1902.
In
1903,
he
graduated
from
MIT
in
Electrical
Engineering,
specializing
in
radio

work.
He
then
worked
for
the
Stone
Telegraph
and
Telephone
Company
in
Boston.
In
1915,
while
in
the
Navy,
Clark
helped
devise
aclassification
system
for
blueprints,
photographs,
documents,
and
general

data.
In
1918,
he
adopted
the
system
for
organizing
his
ra-
dio
collection
and
coined
the
term
"Radioana."
In
1919,
he
joined
the
staff
at
the
Marconi
Telegraph
Company
of

America
and
later
the
Radio
Corporation
of
America
(RCA).
Clark
devised
the
'type
number
system'
used
by
RCA
for
classifying
equipment
(e.g.,
vacuum
tubes).
From
1922
to
1934,
he
was

in
charge
of
exhibits
of
radio
apparatus
at
shows
and
fairs
on
behalf
of
RCA.
In
1928,
he
started a
radio
museum
for
RCA.
The
museum
collection
was
turned
over
to

the
Rosenwald
Museum
in
Chicago,
IL
and
the
Henry
Ford
Museum
in
Dearborn,
MI.
Clark's collection
began
to
assume
some
importance
when
patent
in-
fringement
cases
came
to
court
and
the

documents
provided
substantive
evidence
about
the
radio
industry.
At
his
death,
the
collection
was
given
to
MIT
and,
in
1959,
turned
over
to
the
Smithsonian
Institution.
See
Clark,
George
H.

Radioana
Collection.
Clark, George H. Radioana Collection An
archive
ofhistorical
radio
memorabilia
and
documents
col-
lected primarily between
1900
and
1935
by
radio
engineer
George
H.
Clark.
It
was
transferred
from
the
Massachusetts Institute
of
Technology
to
the

Smithsonian's National
Museum
of
American
His-
tory
in
1959.
It
is
one
of
the
most
extensive
collec-
tions
ofwireless
radio
history
in
the
U.S.,
compris-
ing
more
than
276
linear
feet

of shelf
space
at
the
Amplifier Operations and Emissions Class Categories
Amplifier Categories Description
Class
A
amplifier
A
single-ended
circuit
in
which
output
current
flows
during
the
input
cycle,
as
related
to
the
grid
bias
and
grid
voltage.

Provides
good
fidelity
at
low
receiving
levels.
Class
AB
amplifier
A
circuit
in
which
output
current
flows
for
more
than
half,
but
less
than
the
full,
duration
of
the
input

cycle.
Better
efficiency
than
a
Class
A
amplifier
but
also
has
higher
power
requirements.
Class
B
amplifier
A
circuit
in
which
output
current
flows
for
halfof
the
input
cycle.
More

efficient
than
Class
A
or
Class
AB
but
has
higher
power
requirements
and
can't
be
configured
as
a
single-ended
circuit.
Class
C
amplifier
A
circuit
in
which
output
current
flows

for
somewhat
less
than
halfof
the
input
cycle.
This
provides
high
efficiency
but
also
has
higher
power
requirements.
Emissions Categories Description
Class
AO
emission
Incidental
radiation
emanating
from
an
unmodulated
carrier
wave

transmission.
Class
A1
emission
A
low-speed
carrier
wave
(as
those
used
for
early
telegraphy)
unmodulated
by
an
audio
signal.
Class
A2
emission
An
amplitude-modulated
carrier
wave
modulated
by
low
audio

signals
t~
transmit
simple
tones
or
Morse
code.
Class
A3
emission
An
amplitude-modulated
carrier
wave
modulated
by
audio
signals
so
intelligible
conversation
can
be
transmitted.
184
© 2003 by CRC Press LLC
National
Archives
in

Washington,
D.C.
The
collec-
tion
includes
biographical
information
on
the
pio-
neers
developing
radio
and
photographs
and
docu-
ments
on
the
growth
and
operations
of
radio
compa-
nies,
particularly
National

Electric
Signaling
Com-
pany
and
RCA.
Interestingly,
the
collection
is
ar-
ranged
according
to
a
Navy
filing
system
devised
in
part
by
Clark
in
1915.
See
Clark,
George
Howard.
CLASS

Custom
Local
Area
Signaling
Services.
Tele-
phone
subscriber
calling
options
including,
but
not
limited
to,
Automatic
Callback,
Call
Trace,
Caller
ill,
Selective
Call
Rejection.
In
the
past,
when
demand
for

these
services
was
lower,
they
were
billed
indi-
vidually,
depending
upon
which
ones
were
selected.
More
recently,
phone
companies
have
been
offering
monthly
flat
rate
bundles
on
a
variety
of

these
caller
options.
Class, facsimile
For
information
on
Class
1
and
Class
2
facsimile
standards
and
related
concepts,
see
fac-
simile,
formats.
Class,
IP
See
IF
Class.
class
of
service
CoS.

A
general
designation
for
an
agreed
or
specified
level
of
functioning
or
security,
which
varies
from
industry
to
industry.
In
telecom-
munications,
network
configuration
and
tuning
and
sometimes
billing
levels

are
established
according
to
class
of
service
parameters.
See
quality
of
service.
Classical
IP
A
set
ofspecifications
for
an
asynchro-
nous
transfer
mode
(ATM)
implementation
model
described
in
the
early

1990s
by
the
Internet
Engineer-
ing
Task
Force
(IETF)
for
local
area
internetworking.
In
Classical
IP
implementations,
IP
headers
are
pro-
cessed
at
each
router,
creating
latency
and
limiting
throughput.

Due
to
the
increase
in
demand
for
multi-
media
capabilities,
Classical
IF
is
showing
its
age.
One
of
the
limitations
of
Classical
IP
is
that
direct
ATM
connectivity
exists
only

between
nodes
with
the
same
IP
address
prefix.
See
ATM
models
for
a
chart
of
some historic and new
ATM
models. See
RFC
1577.
ClassmarkAn
electronic
designation
that
identifies
privileges
and
restrictions
associated
with

a
particu-
lar
communications
line
or
trunk.
See
class
of
service.
CLC
1.
Carrier
Liaison
Committee.
2.
Competitive
Local
Carrier.
cleaning arcAbriefelectrical
spark
generated
by
an
electrode
for
the
purpose of removing particulate
matter

from
a
surface.
Cleaning
arcs
are
used
in
fu-
sion
splicers
for
cleaning
the
ends
of
fiber
optic
fila-
ments
prior
to
joining
since
any
undesired
particles
in
the
joint

could
interfere
with
light
transmission.
See
fusion
splicing.
clear
1.
In
computer
monitor displays,
to
blank
a
screen,
applications
window,
or
tenninal
window.
The
clear
command
provides
a
clean
slate,
a

visual
work-
ing
space
without
clutter,
obsolete
information,
or
dis-
tractions.
2.
In
programming,
to
set
a
storage
loca-
tion
(a
buffer,
address,
etc.)
to
a
zero
state,
blank
state

(as
with
space
characters),
previous
state,
or
default
state.
3.
In
communications,
a
clear
signal
is
one
with-
out
noise
or
interference
and
ofsufficient
volume
or
intensity
to
be
heard

or
seen
distinctly.
clear
channell.
In
telephone communications a
transmission
line
that
is
used
entirely
for
communi-
cation,
and
no
control
or
other
signaling
bits
are
be-
ing
transmitted.
In
other
words,

all
the
resources
are
available
for
the
infonnational
communication.
2.
In
radio
communications,
a
station
that
is
permitted
to
dominate a frequency
and
broadcast
at
a certain
power
level
or
up
to
a certain distance (e.g.,

750
miles)
during
a
specified
time
of
day.
A
type
of
ex-
clusive
frequency
arrangement.
clear to send
CTS.
A
handshaking
signal
provided
when
the
communication
has
been
set
up
over
a

se-
rial
link,
and
the
called
modem
is
ready
to
receive
information.
See
RS-232.
clearance
In
electrical
installation,
the
shortest
dis-
tance
between
separated
live
conductors,
or
between
live
conductors

separated
from
physical
structures,
or
between
live
conductors
separated
from
associated
grounds.
See
gap.
cleavage plane Aplanar direction
in
a
material
in
which
the
molecular
bonds
that
hold
the
substance
together
can
be

more
readily
cleaved.
Many
materi-
als
have
a "grain," a
general
direction
in
which
the
fibers
or
lattice
structure
are
aligned.
Thus,
most
pa-
per
tears
more
readily
in
one
direction
than

another
and a number
of
materials used
in
electronic
compoents
will
cleave
more
readily
depending
upon
the
orientation of
the
material
with
respect
to
the
cleaver.
For
example,
birefringent
materials,
those
with
a molecular structure that
is

the
same
in
two
planes
and
different
in
a
third,
will
generally
cleave
more
readily
when
nicked,
broken,
sawed,
or
sliced
across the plane
in
which the bonds
are
weaker.
Knowledge
of
the
composition

of
materials
and
their
cleavage
plane
is
useful
in
materials
science
and
ma-
terials
and
component
fabrication.
See
cleave.
cleave
To
cut
or
break
a
cable
or
component
so
the

broken
surface
meets
certain
needs,
as
in
junctions,
solder
joints,
or
optical
connections.
With
basic
elec-
tricity-conducting
wires,
the
angle
or
cleanliness
of
the
break
in
a
line
is
not

usually
critical,
as
wire
can
be
readily
wrapped
or
soldered
in
place
without
sig-
nificant
loss
to
the
signal.
However,
with
layered
wires or certain electronic components, where a
smooth
or
straight
surface
might
be
important

to
the
electrical
contact,
or
in
fiber
optic
cable,
where
rough
edges
can
degrade
the
light-carrying
properties
of
the
fiber,
a
precise
cleave
is
critical.
Wire
is
usually
cleaved
with

scissors,
knives,
or
spe-
cialized
cutters,
depending
upon
the
gauge
of
wire
and
the
importance
ofa
clean
cleave.
Fiber
optic
fila-
ments
are
usually
cleaved
with
mechanical
blades,
but
some

systems
use
ultrasonics
for
the
very
precise
cleaves desired
for
fusion splicing.
See
cleavage
plane,
cleave
angle,
cleaver,
crimp,
fiber
optic;
fu-
sion
splice.
cleave angle
The
angle
at
which
a
surface
is

cut
rela-
tive
to
a
reference.
Cleaving
is
often
done
prior
to
creating
a
glued
or
fused
joint
or
adding
a
connector,
but
it
may
also
be
used
to
provide

an
unimpeded
exit
path
for
an
optical
signal
(e.g.,
a
fiber
optic
sign
or
lighting
fixture).
185
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
Cleave
-
Basic
Types
that
produce
a cleaner
cleave

and
claim
that
polish-
ing
is
not
necessary.
For
complex
bundled
assemblies,
polishing
may
still
be
necessary.
1
C
C
__
B
A
There
are
anumber
of
ways
to
cleave a

wire
or
cable,
depending
upon
the materials.
Wires
andplastics
can
often
be
cut all the
way
through
with
a knife
(A)
or
snippers that cut
from
both
sides,
especially
if
rough
edges
aren
1a concern. Hard plastics and some
me-
tallic compounds often cleave better ifnickedfirstand

bent until they break at the point
of
the nick
(B)
(the
effectiveness
of
snapping depends partly
upon
the di-
rection
of
the grain). Glass may break more cleanly
and evenly
if
nicked or scored
(C)
and
then
snapped.
Nicking and snapping often provides the best cleave
forfiber opticfilaments.
Fiber
optic
cleavers
come
in
many
shapes
and

sizes.
Some
resemble
microscope
components,
with
view-
ing
and
testing
capabilities,
some
have
computer
in-
terfaces
for
magnifying
or
analyzing
diffraction
pat-
terns
in
the
filament
that
has
been
cleaved,

some
sup-
port
polishing
components,
and
some
are
compact
units
resembling
staplers.
Sizes
range
from
handheld
to
table-top.
Mid-sized
cleavers
for
field
work
may
have
tripod
mounts
for
securing
in

a
mobile
lab
or
an
outdoor
or
in-plant
location
where
there
is
no
flat
workspace
for
setting
up
the
cleaver.
Since
fiber
scraps
can
get
in
the
way
and
present

a
safety
hazard
(the
shards
are
small
and
sharp)
a
tray
for
collecting
the
fiber
end
scraps
is
sometimes
in-
cluded
with
cleaving
devices.
It
is
important
to
shield
the

eyes
with
safety
goggles
and
to
remove
any
fila-
ment
shards
not
discarded
into
trays
when
working
with
cleavers.
"
It,
The
angle
of
a cleave will influence the amount
of
surface
area
that
is

availablefor connectingorfusing
a fiber optic filament.
The
smaller the angle, the
greater the surface
area.
This
has advantages and
dis-
advantages. A largersurface
area
may
provide added
strength
in
certain directions andastrongerfuse,
due
to
the larger surface
area,
but it
also
is
more
difficult
to
cut and match and creates a larger
area
in
which

contaminants or aberrations
in
a joint
can
interfere
with light transmission.
A straight
(90")
angle
is
used
when
the
filament
is
being terminated, hand spliced, orspliced with a
ma-
chine that
is
set
to
rotate
the
two
ends independently
prior
to
splicing.
Angle cuts must
be

carefully matched
if
they
are
to
be spliced, because
even
the
smallest
angle,
if
the
ends
are
aligned perfectly,
can
cause a
gap that interferes
with
light propagation.
Cleave
Angle
Effects
y

x
In
wires
and
fiber

optic
filaments,
the
angle
is
mea-
sured
relative
to
the
lengthwise
conductive
core
and
is
usually
described
and
handled
in
two
planes.
Thus,
if
the
core
is
horizontal
(in
the

X
plane),
the
cleave
angle
is
described
in
terms
of
its
angle
as
it
rotates
through
the
X-V
plane.
There's
no
reason
why
the
angle
in
the
Z
plane
couldn't

also
be
described,
but
in
most
fabrication
technologies
for
wire
and
cable
splicing
and
attachment,
the
Z
plane
is
kept
at
right
angles
to
the
X
reference
for
simplicity
(and

because
there's
usually
no
added
benefit
in
altering
Z
angles).
Cleave
angles
vary
depending
upon
the
materials
being
cut,
the
cleaver,
the
purpose
of
the
cleave,
and
any
tension
factors

that
may
act
upon
a
cable
that
is
to
be
cleaved
and
spliced.
A
90
0
cleave
may
be
easier
to
cut
and
fuse
and
may
provide
abetter
unimpeded
path

for
signals
due
to
the
smaller
fused
cross-sec-
tion,
but
an
angled
cleave
(e.g.,
45°)
may
provide
a
stronger
connection
due
to
the
larger
fusing
area
and
may
withstand
better

forces
against
the
fused
joint.
F
or
end-emitting
fiber
filaments
intended
for
signage,
artworks,
or
lighting
fixtures,
an
angled
cleave
can
influence
the
shape
and
the
amount
of
light
that

es-
capes
from
the
endpoint.
See
cleave.
cleaver,
fiber optic A
device
specifically
designed
to
provide
the
precise,
clean
cleaves
required
for
fus-
ing
fiber
optic
filaments
together,
or
for
attaching
connectors

to
a
fiber
filament.
Tolerances
are
usually
within
0.5°.
Traditionally,
optical
fibers
to
be
coupled
with
other
components
were
cleaved
and
then
polished
to
pro-
vide
the
cleanest
surface
possible

at
the
terminal
ends.
However,
some
manufacturers
now
promote
products
186
© 2003 by CRC Press LLC
The
cleaving blades
may
be
specialized for the
diameter
range
and
type
of
fiber
to
be
cut
(glass
or
plastic).
There

may
be
different
blade
heights
and
ro-
tations
to
accommodate
different
sizes.
See
cladding
alignment
splicer,
crimp,
interferometer.
Cleave
Area
and
Strength
t
't,
90°
t
f',
In
fiberfilaments, cleaves intendedfor splicing must
be

clean
and precise
to
prevent
inte171lption
or back
reflection
of
a light signal passing
through
the
joint.
The
angle
of
the cleaves
to
bejoinedshouldmatch
(in
most
cases)
tofacilitatefusion. Narrower angles
(e.g.,
45
0
from perpendicular
in
the orientation shown
above)
create

larger surface areasforfusion and may
resist
breakage
from
forces
in
certain directions, but
may
also
influence
the
lightguiding properties
of
the
joint if
the
angles
don
~
match rotational characteris-
tics
of
the fiber (e.g.,
in
polarized cables). Angle
cleaves
are
generally
more
difficult

to
cut and
splice,
especially
with
hand
tools.
CLEC
See
Competitive
Local
Exchange
Carrier.
Clerk-Maxwell,James
See
Maxwell,
James
Clerk
click tones A
signaling
system
common
on
phone
systems,
especially
wireless
phones,
that
alerts

the
user
that
the
call
is
being
processed.
clickstreamslangA
description
of
the
flow
of
events
and
sites
visited
when
a user
navigates
the
Internet,
particularly
the
Web,
which
is
connected
through

clickable
hyperlinks.
Product
vendors
have
an
intense
commercial
interest
in
monitoring
user
behavior
and
maneuvering
users
to
their
sites.
cleavage client A
system
or
application
that
serves
the
user
but
that
may

seek
or
require
information
or
operating
parameters
through
a
host
with
a
higher
pri-
ority
or
greater
capabilities.
In
the
past,
host
and
cli-
ent
have
had
almost opposite meanings
for
some

computer
administrators,
but
for
consistency
in
this
dictionary,
and
because
the
trend
is
in
this
direction,
client
is
defined
as
the
adjunct
or
subservient
system
or
application.
See
host.
client application

In
a client/server
computer
soft-
ware
application,
the
client
is
typically
the
applica-
tion
used
by
the
user
to
communicate
to
a
source
or
destination
through
a
related
higher
priority
or

more
powerful
(or
just
different)
server
program.
The
N
et-
scape
Communications
Web
browser
is
an
example
of a
common
client
application
that
communicates
to
Web
sites
through
a
Web
server,

handles
the
traf-
fic,
and
provides
some
measure
of
security.
client operating system
On
a
network,
the
operat-
ing
systems
run
on
client
machines,
user
tenninals,
and
subsidiary
machines.
These
do
not

have
to
be
the
same
as
the
server
operating
system.
A
good
server
can
handle
a variety ofclient
OSs
and
network
be-
tween
them
seamlessly,
using
standard
network
pro-
tocols.
For
example,

you
may
have
a
network
that
is
configured
with
a
Sun
workstation
and
Sun
operat-
ing
system
(SunOS,
Solaris)
as
the
main
server,
with
a
number
of
different
client platfonns
connected

to
it,
running
different
client
operating
systems
and
op-
erating environments, such
as
Linux, Apple
Computer's
as
x,
Be
Inc.
's
BeOS,
or
Microsoft
Win-
dows.
client/server modelA
computer
processing
method
of
improving
efficiency,

and
sometimes
security,
by
selectively distributing activities.
In
human
enter-
prises,
there
is
often
a
manager
with
an
overall
knowl-
edge
of
the
work
to
be
done,
security
clearance,
and
the
authority

to
designate
tasks
and
respond
to
re-
quests.
In
conjunction
with
the
manager
are
workers
with
knowledge
of
specific
tasks
and
needs,
lower
security clearance,
and
instructions
to
report
their
findings

and
to
direct
their
questions
and
requests
for
resources
to
the
manager.
Aclient/server
model
on
a
computer system
is
similar
to
this.
An ISP's
Web
server
has
the
logic
and
security
clearance

to
accept
requests
from
many
Web
browsers,
and
to
fetch
the
infonnation
and
serve
it
back
to
the
browsers
which
then
fonnat
and
display
the
information
for
the
user.
Most

networks
work
on
client/server
models,
where
the
server
handles
administrative
details,
file
man-
agement,
and
security,
and
the
client
machines,
usu-
ally
tenninals
or
desktop
computers,
handle
input
and
output,

local
processing,
and
display.
CLIP
calling
line
identification
presentation
(e.g.,
as
in
ISDN
Q.81
and
Q.731
number
identification
ser-
vices).
clipboard
In
most
operating
systems,
and
in
some
software
programs,

an
area
of
memory
or
a
file
on
a
hard
drive
designated
to
hold
information
(usually
images
or
text,
but
may
also
be
sound
or
video
clips)
that
has
been

cut
by
the
user
for
later
retrieval.
Most
clipboards
store
only
one
clip
at
a
time,
with
subse-
quent
clips
over-writing
previous
ones,
so
that
only
the
most
recent
can

be
retrieved.
Some
clipboards
can
handle
multiple
clips,
and
some
store
the
informa-
tion
on
disk
for
later retrieval.
On
the
Macintosh,
for
example,
auser
can
save
clips
by
copying
or

cutting
them
and
storing
them
in
the
Scrapbook.
Clips
can
be
retrieved later
by
paging
through
the
clips,
select-
ing
those
desired,
and
copying
and
pasting
them
back
into
an
application.

ClipperchipA
microprocessor
chip
that
provides
se-
curity
encryption
features
that
can
be
incorporated
into
electronic
devices.
The
Clipper
chip
has
become
the
focal
point
for
broad
and
heated
debates
over

the
privacy
of
global
communications.
The
U.S.
federal
187
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
governing
bodies
had
initiated
plans
to
include
the
chip
in
consumer telecommunications products,
to
secure conversations
from
anyone
but

the
govern-
ment.
The
plans
were
initially announced
in
1993
through
the
White
House
Escrowed
Encryption
Ini-
tiative.
The
system
was
designed
by
the
National
Security
Agency
(NSA).
Three
versions
of

the
pro-
posal, Clipper
I,
II,
and
III
were
promoted
between
1993
and
1996.
Most
people
agree
that
there
is
a
need
for
voluntary,
widely
available
encryption
options
for
government
and

private
use,
and
vendors
agree
that
standards
pro-
vide a
means
for
them
to
distribute products
with
intercompatibility.
But
on
this
issue,
concern
has
been
expressed
about
how
the
government
is
intending

to
implement
and
enforce encryption policies,
and
on
their
assertion
that
the
system
will
work
only
if
made
mandatory. There
has
been
a considerable outcry
from
vendors
and
the
public,
who
questioned
the
ro-
bustness

of
the
technology,
and
who
are
gravely
con-
cerned
about
too
much
power
being
in
the
hands
of
too
few
people.
In
spite of
the
negative
feedback,
the
Department of
Commerce
approved

the
Escrowed
Encryption
Stan-
dard
(EES)
as
a voluntary Federal Information
Pro-
cessing
Standard
(FIPS)
in
1994.
One
of
the
require-
ments
would
be
that
every
Clipper
chip
would
have
its
unique
key

registered
with
the
federal
government
and
held
in
split
form
by
two
federal
escrow
agents
(NIST
and
the
Treasury
Department),
creating
acces-
sibility
for
the
federal
government
to
wiretap
secure

communications.
The
debate
over
the
chip,
privacy,
and
law
enforcement
led
in
the
fall
of
1994,
to
the
Encryption
Standards
and
Procedures
Act,
which
de-
scribed
federal
policy
governing
the

development
and
use
of
encryption
technology
for
unclassified
infor-
mation.
Back
references
were
made
to
The
Computer
Security
Act
of
1987.
The
public
responded
in
many
ways
to
the
various

proposals regarding
the
Clipper
chip.
Some
sought
to
point
out
flaws
in
the
process
and
design;
others
created
free
user-encryption
programs
that
would
de-
feat
the
Clipper
system.
One
of
the

more
significant
challenges
to
the
system
was
the
X9
Accredited
Stan-
dards
Committee
(ASe) announcement
that
it
would
develop a competing
data
security standard based
upon
triple-DES.
The
ASC
sets
data
security
stan-
dards
for

the
U.S.
financial
industry.
The
Clipper
chip
uses
a
nonpublic
encryption
algo-
rithm
called
SKIPJACK
which
cannot
be
read
off
the
chip
and
is
designed
so
that
it
cannot
be

reverse
en-
gineered.
According
to
the
EES,
when
two
devices
negotiate a
communication,
they
must
both
have
se-
curity
devices
with
Clipper
chips
and
must
agree
on
a
session
key,
which

may
be
a
public
key
such
as
RSA
or
Diffie-Hellman.
The
message
is
then
encrypted
and
sent
with
a
law
enforcement
access
field
(LEAF),
a
serial
number,
authentication
string,
and

a
family
key.
When
received,
the
LEAF
is
decrypted,
the
authen-
tication
string
verified,
and
the
message
decrypted
with
the
key.
See
Capstone
chip,
LEAF,
Pretty
Good
Privacy,
SKIPJACK.
188

clipping I. In software applications, cutting out
information,
such
as
graphics,
text,
sound
or
video,
usually
for
later
retrieval
or
insertion
elsewhere.
See
clipboard.
2.
In
graphics programs,
the
process ofre-
moving
parts of
an
image,
or
of
the

display outside
some
designated
boundary,
usually
the
outer
margin
ofapicture,
or
of
an
application's
window.
Informa-
tion
that
is
clipped mayor
may
not
be
retained
in
memory.
Often
a
program
will
retain

the
information,
even
if
the
user can't
see
it,
so
the
user
can
quickly
restore
the
information or scroll quickly through
the
image
without recreating
it
or
having
to
wait
for
the
computer
to
reread
it

from
disk.
3.
In
audio,
a brief
loss
of
sound,
especially
at
the
beginning
or
end
ofa
transmission
due
to
limitations of
the
technology
(limited
frequency
range,
direction
flipping,
ramp-up
time).
4.

In
audio
communications, especially phone
calls
over satellite
links,
the
equipment
may
be
oper-
ating
part of
the
time
in
half
duplex
mode,
transmit-
ting
in
only
one
direction
at
a
time,
so
gaps

in
the
con-
versation
may
cause
a switch
in
the
other direction
and
clip
part of
the
conversation.
CLIR calling
line
identification restriction (e.g.,
as
in
ISDN
Q.
81
or
Q.
731
number
identification
services).
CLLI

See
Common
Location
Language
Identifier.
clock
1.
A
time-keeping
and
reporting
device
that
uses
various
gravity
(sand,
weights)
or
oscillating
mecha-
nisms
(radioactive
decay,
emissions, crystal vibra-
tions)
to
track
time.
Quartz

crystals
have
extremely
consistent
vibrations
that
are
sometimes
used
to
make
very
accurate
clocks.
2.
A
device
that provides
regu-
lar
signals
for
use
as
a
timing
reference.
On
a
com-

puter,
instruction
speeds
are
expressed
in
clock
cycles.
clock bias
The
discrepancy
between
the
time
indi-
cated
on
a clock
and
True
Universal
Time.
See
Co-
ordinated Universal
Time.
clock doubling A
means
ofgetting a little
more

per-
formance
out
ofa computer instead of
having
to
re-
place
the
system.
With
constant
demands
for
faster
systems,
balanced
by
the
high
cost
of
replacing
a
sys-
tem
that
may
be
only

a year
old
or
less,
some
manu-
facturers
have
provided versions of
the
CPU
chip
or
accelerator accessories that effectively double the
speed
of
the
CPU.
This
does
NOT
mean
performance
is
doubled.
The
CPU
is
only
one

part
ofa
system,
and
the
bus
rates,
coprocessing
chips,
sofrware
design,
op-
erating system parameters,
and
other
factors,
will af-
fect
the
actual performance
increments
to
a
great
ex-
tent.
In
other words,
the
speedup

is
usually
more
on
the
order of20%
or
so
but,
for
graphics
computations
or
resource-hungry
sofrware,
that
might
be
an
impor-
tant
20%.
Sometimes
it's
worth
it;
it
depends
upon
the

cost
of
the
doubler.
clock speed
In
computer
systems,
an
expression of
the
speed
ofa central processing
unit
(CPU)
or
other
processing
chip,
usually
expressed
in
megahertz.
Mi-
crocomputers
in
the
1970s
ran
at

clock
speeds
rang-
ing
from
about
I
to
4
MHz.
In
the
1990s
,
they
ran
at
about
200
to
300
MHz.
Current microcomputers
in
consumer
price
ranges
run
at
over

700+
MHz.
Clock speed
is
not equivalent
to
system speed.
Doubling
the
clock
speed
doesn't
mean
doubling
the
© 2003 by CRC Press LLC
computing
speed;
sometimes
the
efficiency
is
just
slightly
more,
and
sometimes
it
is
three

or
four
times
more.
Determining
the
overall
speed
ofa
computing
system
is
complex
and
requires
evaluation
of
the
gen-
eral
architecture
of
the
system,
the
efficiency of
the
operating
software,
the

amount
of
memory,
the
in-
clusion
of
coprocessing
chips,
and
the
type
of
appli-
cation
being
run.
For
example,
the
author's
first
8-kilobyte
RAM
(yes,
kilobyte,
not
megabyte),
1.8-MHz
system

ran
tele-
communications
software
and
word
processors
very
effectively
at
typing
speeds
of
over
80
wmp.
A
fea-
ture-rich,
well-written
graphical
word
processor
can
run
very
efficiently
on
an
8-MByte

RAM,
10-MHz
system.
The
same
software
running
on
a
16-MByte
233-MHz
system
often
is
not
perceptually
faster
be-
cause
text
entry,
at
its
basic
level,
is
not
a
computing
intensive

application.
In
contrast
with
basic
word
processing,
computing-
intensive
applications,
however,
can
be
dramatically
affected
by
clock
speed.
A
stock
1.8-
MHz
system
is
essentially
incapable
of
doing
3D
ray-tracing

in
a
rea-
sonable
amount
of
time,
whereas
an
older
Amiga
computer
with
a
clock
speed
of
only
7.16
MHz
can
render
a
complex
3D
scene
in
3
or
4

days,
faster
than
many
25-MHz
computers
with
different architec-
tures.
Amigas
with
40-
MHz
accelerator
cards
can
ren-
der
the
same
scene
in
3
or
4
hours,
and
dedicated
graphics
systems,

running
on
parallel
processing
sys-
tems,
or
current
Silicon
Graphics
Machines,
for
ex-
ample,
can
accomplish
the
same
feat
in
minutes
or
seconds.
Since
computing
speed
is
important
to
computer

elec-
tronics
designers,
a
number
of
measures
have
been
established
to
provide information
for
comparing
chips,
systems,
or
architectures.
These
benchmark
tests
are
not
absolute
measures
of
clock
speed,
but
they

provide
some
information
that
is
helpful
and
they
generate
some
pretty entertaining
controversy.
See
benchmark,
clock
doubling,
Dhrystone,
Whetstone.
clone
n.
1.
Duplicate,
exact
copy,
genetically
identi-
cal
individual.
2.
A

software
program
or
device
con-
figured
to
masquerade
as
another
device,
either
for
diagnostic
purposes,
interim
use,
or
fraud.
clone fraud A
method
of
gaining
entry
to
a
system,
or
using
a

device,
by
simulating
a
user,
serial
num-
ber,
or
access
code.
Cellular
phones
are
particularly
susceptible
to
clone
fraud,
as
it
is
not
difficult
to
pro-
gram
a
legitimate
serial

number
into
another
cellular
unit.
See
tumbling.
closed architectureA
proprietary
design
that
is
sup-
ported
and
enhanced
by
peripherals
that
conform
to
its
particular specifications,
and
that
may
not
be
manufactured
by

third
party
vendors,
except
perhaps
by
obtaining
special
permissions
or
paying
royalties.
Contrast
with
open
architecture.
closed captioning
CC.
A broadcast technique
for
transmitting
text,
usually
to
be
superimposed
over
a
corresponding television image.
CC

is
provided
mainly
as
an
aid
for
the
hearing
impaired,
although
in
some
cases
it
may
also
be
used
to
provide
subtitle
translations.
It
is
typically
sent
on
the
vertical

blank-
ing
interval
of
the
transmission,
and
a
decoder
may
be
required
to
interpret
the
signals.
closed circuitA
broadcast
circuit
in
which
the
send-
ing
and/or
receiving
components
are
limited
to

a
cer-
tain
frequency
range
or
power
level.
Thus,
a
closed
circuit
radio
system
within
a
complex
may
be
set
to
send
and
receive
FM
signals
at
89
hertz.
A

radio
sta-
tion
may
have
permission
to
broadcast
at
only
91.7
hertz
on
frequency
modulated
(FM)
signals.
In
con-
trast,
an
open
circuit
is
one
that
is
not
restricted
to

a
narrow
frequency
range,
as
a
CB
radio,
for
example,
which
may
be
set
to
pick
up
signals
broadcast
over
a
variety
of
channels.
closed circuit broadcast, closed circuit
TV
A
radio
or
television

transmission
that
is
broadcast
to
a
small
or
restricted
audience,
often
within
a
specific
build-
ing
complex
or
campus.
Low
power
frequency
modu-
lated
(FM)
ranges
are
often
used
for

this
type
of
trans-
mission
because
they
are
not
as
strictly
regulated
as
higher
power
transmissions.
closet A
room,
cabinet,
or
case
used
for
terminating
blocks
or
patch
panels
for
wiring

configurations.
The
.
closet
serves
a
variety
of
aesthetic,
safety,
organiza-
tion,
and
security
purposes.
cloud network
Frame
Relay
network
connections
are
now
offered
as
a
lower
cost
alternative
for
small

busi-
nesses
and
educational
institutions,
and
a
cloud
re-
lay
is
one
connectionless
option
of
this
type
in
which
resources
are
shared,
usually
among
four
or
five
small
subscribing
organizations.

CLP
cell
loss
priority.
A
one-bit
ATM
networking
cell
header
toggle
indicating
the
relative
importance
of
the
cell.
CLP
is
important
as
there
are
various
mecha-
nisms
in
ATM
for

prioritizing
cell
traffic,
or
discard-
ing
cells
in
congested
situations.
See
cell
rate.
CLR
See
cell
loss
ratio.
CLTP
See
Connectionless
Transport
Protocol.
CLTS
Connectionless
Transport
Service.
cluster
1.
In

cellular
communications,
a
unit
consist-
ing
ofa
group
of
adjacent
cells
within
which
chan-
nels
are
not
reused.
See
cell,
cellular
phone,
mobile
phone.
2.
A
set
of
workstations
or

terminals
in
the
same
general
physical
or
virtual
networked
grouping.
These
may
share
more
than
physical
connectivity;
they
may
also
have
shared
devices
that
manage
pro-
cessing
input
and
output,

or
specialized
requests
of
the
cluster.
See
cluster
controller.
3.
A
combined
unit
of
disk
storage
allocation,
usually
consisting
of
four
or
more
sectors.
clustercontrollerA
device
controlling
communica-
tions
input/output

for
multiple
connected
devices.
clutter
Wave
reflections
from
obstructions
such
as
terrain
and
buildings,
which
may
show
up
as
echoes
or
unidentifiable
blips
on
a radar
screen,
thus
inter-
fering
with

scanning.
CMA
See
Communications
Management
Association.
CMC
See
connection
management
controller.
CMI
See
coded
mark
inversion.
CMIP
See Common Management Information
Protocol.
CMOL
CMIP
Over
LLC
(Logical
Link
Control).
See
Common
Management
Information

Protocol.
189
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
CMOS Complementary Metal Oxide Semiconduc-
tor.
A semiconductor
chip
that combines p-channel
and
n-channel
MOS
in
a single substrate with push-
pull circuits.
Slow,
but
noise
resistant,
and
good
for
battery-operated
devices.
CMOS
RAM
needs

a
small
stream
of
constant power
to
preserve information
stored
in
its
memory,
which
is
typically supplied
by
a lithium battery (available
in
photography
and
elec-
tronics stores). Default settings
and
sometimes video
card
and
other peripheral parameters
may
be
stored
in

CMOS
RAM
linked
with
a lithium battery
on
a
computer's motherboard.
See
PRAM.
CMOT
CMIP
Over
TCP.
See
Common
Management
Information Protocol.
CMR
See
cell
misinsertion rate.
CMRS/PMRS commercial mobile radio service/pri-
vate mobile radio service.
The
Federal Communica-
tions
Commission
(FCC)
was directed, through

the
Omnibus Budget Reconciliation
Act
of
1993,
to
auc-
tion radio spectrum
for
CMRS.
Unfortunately,
the
initial spectrum allocations
in
the
C
and
F blocks,
intended
for
small businesses,
did
not work
out
well
in
practical use. After numerous discussions
and
bankruptcy lawsuits,
the

FCC
announced
the
cancel- .
lation ofcertain licenses
and
began
to
reauction por-
tions of
the
C
and
FBlock
radio
spectrum, beginning
in
2000.
See
ABlock
for
a chart offrequencies.
See
Omnibus Budget Reconciliation
Act.
CMTS Cellular Mobile Telephone System.
CMYKA
color
model
widely

used
in
the
paper
print-
ing
industry.
The
initials signify
cyan,
magenta, yel-
low,
and
black,
which
are
the
four
colors combined
as
tiny
dots
in
process color printing jobs
to
simu-
late
all
hues
and

black.
Black
is
included because
the
combination of
the
first three
does
not
give
a dark,
rich, black
pigment.
Metallic colors cannot
be
pro-
duced
within
this
color
model,
and
extra
runs
through
the press or spot application
of
metallics
on

a
multi
color printer
are
necessary
to
accommodate
me-
tallic effects. Computer publishing software often
seeks
to
simulate
these
colors
on
the
monitor
in
or-
der
to
provide
WYSIWYG
in
the
[mal
printed result.
CN
complementary network.
CNA

I.
Centralized Network Administration. A
means ofconsolidating network-related connections
in
a single location, usually a wiring closet
or
panel,
rather
than
distributing
them
in
various parts of
the
premises.
2.
Cooperative Network Architecture.
CND
I.
Calling Number Delivery.
2.
Calling Num-
ber
Display.
.
CNET Centre National d'Etudes des Telecom-
munication,
now
France Telecom
R&D.

CNG A calling
tone
emitted
by
facsimile machines
that
lasts
about
half a second
and
repeats
as
many
times
as
the
software dictates,
to
signal
its
presence
and
to
try
to
establish a negotiation with a receiving
fax
machine. Most machines default
to
about

45
sec-
onds
of
tone
sequence
before
they
disconnect, ifthere
is
no
successful connection. This
time
may
not
be
enough
for
some
systems
or
for
a long-distance
con-
nection
and
some
fax
machines
and

fax
modems
have
an
option
for
extending
it.
190
Most
fax
machines
now
automatically
dial
and
emit
the
CNG.
However, some
of
the
older
fax
machines,
or
bargain basement varieties, still require a human
operator
to
dial

the
number.
The operator must
then
wait
to
hear a
fax
response
and
start the
fax
machine
CNG
by
pressing abutton. This method
is
a problem
if
the
system that
has
been dialed
has
a sensing
de-
vice
to
route incoming calls
to

a phone,
modem,
or
fax
machine depending upon
the
tone.
If
a human
dials
the
line
as
a voice call,
the
switcher will route
it
to
a phone,
and
then
starting
the
calling fax's
CNG
does
no
good,
as
the

phone
has
no
way
of
routing
the
call
back
thJough
the
switcher
to
the
fax
machine.
However, with increasing automation
and
decreas-
ing
cost ofbetter
fax
machines,
this
problem
is
be-
coming
less
prevalent.

CNIS Calling Number Identification Services.
CNR
I.
See
Complex Node Representation.
2.
cus-
tomer not
ready.
CNRI Corporation
for
National Research Initiatives.
CO
I.
cash
order.
2.
See
central office.
3.
command-
ing
officer.
co-channel interference
CCl.
Aquantitative expres-
sion
ofinteference
in
acommunications circuit when

multiple channels
are
arranged
in
such
a
way
that
they
may
interfere
with
transmission
on
a neighboring
or
associated channel.
This
concept
is
especially impor-
tant
in
wireless communications
in
which increasing
numbers of subscribers are being accommodated
within limited frequency allocations.
One
way

to
reduce
CCI
is
with guard bands, but
the
tradeoff
is
lost bandwidth. Another way ofreducing
CCI
is
with adaptive beam forming. See antenna,
smart.
COAM
See
Customer Owned And Maintained.
coaxial cableA transmission cable consisting essen-
tially of
an
irmer
conducting core surrounded
by
a
conducting tube, each insulated
and
all
wrapped
to-
gether
in

an
outer protective sheath.
The
inner core
is
a metallic conductor surrounded
by
a
metal
shield,
that
acts
as
a Faraday
cage,
with a dielectric mate-
rial
interposed between them. Typically,
the
signals
are
propagated
in
one
direction along
the
conduct-
ing
core.
Coaxial cable was

an
important development
for
the
transmission
of
telegraph, telephone,
and
television
signals
as
it
was
found
to
conduct radio frequency
(RF)
signals
well.
By
the
late I
940s,
much
of
the
east-
ern
United States
was

interconnected with coaxial
cable.
Coaxial cables
are
typically
described
in
terms
oftheir
impedance; values from
50
to
95
ohms
are
com-
mon.
The video industry makes extensive
use
of75-
ohm
coaxial cables
for
interfacing cameras, frame
synchronizers,
and
recording
decks.
In computer
net-

working, 75-ohm cables
are
used
for
unbalanced EI
connections. Higher impedance
100-
to
120-ohm
twisted-pair
wire
is
used
for
balanced EI connections,
and
subrate cabling
in
trunk/circuit lines.
coaxial omniguide Alightguiding cable based upon
layered
film
mirror technology developed
at
MIT
in
the
late
1990s
in

a project
led
by
Francis
W.
Davis.
© 2003 by CRC Press LLC
By
2000, project participants had established
Omniguide
Communications
to
further
develop
and
market a transmission
cable
based
upon
the
technol-
ogy
that
would
reflect awider
range
of
wavelengths
in
a

smaller
space
without changing
the
polarity
or
creating
pulse
distortion characteristic
of
traditional
cables.
COBOL
Common
Business-Oriented
Language.
A
verbose, high-level programming language once
widely
used
for
business
applications
and
still
taught
in
business
schools,
but which

is
slowly being
re-
placed
by
other
languages.
See
OO-COBOL.
CoBRAA
commercial,
portable,
ISDN
analyzer
for
installation, maintenance, and troubleshooting
of
ISDN Basic or Primary Rate networks, from
Consultronics. Consultronics now markets the
CoBRA-CQ
as
a
portable
local
loop
test
set
for
ISDN,
ADSL,

G.lite
and
other
formats.
COBRA
A
frequent
misspelling of
CORBA,
Com-
mon Object Request Broker Architecture. See
CORBA,
Object
Request
Broker.
COBRAS
Cosmic
Background
Radiation
Anisotropy
Satellite.
COCOT
customer-owned coin-operated
telephone.
See
payphone,
private.
COD
connection-oriented
data.

code
1.
A
system
of
symbols,
cyphers,
characters,
images, movements, sounds, or other meaningful
marks
or
actions
that
serve
to
represent
ideas
and
lan-
guage
in
a
way
that
is
not
commonly
understood
or
recognized.

Not
all
symbolic
forms
of
communica-
tion
are
considered
to
be
codes.
For
example,
Ameri-
can
Sign
Language
is
not
understood
by
many,
but
it
is
not
considered a
code
in

the
sense
that
informa-
tion
on
learning
it
is
readily available
in
schools
and
libraries.
Social
changes
can
alter
the
perception ofwhether
something
is
a
code.
Before
the
development
of
the
printing

press
and
public education, text
and
reading
were
mainly
restricted
to
the
elite
political leaders,
and
common
people probably considered
it
as
a sort
of
code.
The
use
ofcoded information
is
common
in
wartime,
or
with
politically

or
economically
sensi-
tive
infonnation.
Some
codes
are
exceedingly
sophis-
ticated
and
difficult
to
break. Until recently,
most
analog
communications
have
not
been
coded
to
pro-
tect
privacy,
due
to
the
difficulty of

doing
so.
With
recent
digital
technology,
it
has
become
much
easier
to
code
communications,
and
many
software
devel-
opers
and
equipment
makers
are
adding
encoding
to
their
products.
Many
satellite communications,

cell
phone
messages,
and
computer
data
communications
are
now
encoded.
2.
An
abbreviated
means
ofrepre-
senting
information
in
order
to
save
time
in
its
tran-
scription
or
transmission,
or
to

send
it
over limited
transmissions
devices,
and
sometimes
also
to
shield
it
somewhat
from
prying
eyes.
Shorthand
is
a
type
of
code
intended
to
save
time
in
taking
oral
dictation.
Drumbeats

or
smoke
signals
are
two
types
of
codes
designed
to
abbreviate information
so
that
it
is
prac-
tical
to
transmit
through
these
basic
means.
Basic
telecommunications
codes
have
been
in
devel-

opment
since
the
1600s.
Schilling
developed
a
needle
telegraph
code
in
1832.
Morse
(Vail)
code
is
a
widely
used
alphabet coding system developed
in
the
early
1830s.
It
is
still
often
used
in

telegraph
and
radio
com-
munications,
particularly
in
countries
with
limited
ac-
cess
to
computer
equipment.
See
semaphore,
Baudot
code,
Hollerith,
Morse
code.
3.
Computer
program-
ming
code
is
a
system

of
linguistic
and
symbolic
char-
acters
and
syntax
that
serves
to
represent
computer
instructions
so
they
can
be
run
directly
by
the
ma-
chine
or
compiled
into
machine-readable
form.
Code designations in

packet
networking
See
Link
Control
Protocol
codes.
Code Division Multiple Access
CDMA.
A digital,
wireless
communications
service
based
upon
spread-
spectrum
technology,
which
claims
to
provide
about
10
times
the
capacity of
analog.
Access
to

the
local
exchange
is
wireless.
This
technology
was
originally used
in
military
sat-
ellites
for
its
security features
and
resistance
to
jam-
ming.
Now
more
widely used
in
commercial
appli-
cations, it provides
access
to

many
users
at
a
time
without
the
multiple
user
interference
associated
with
other modulation techniques.
The
same
frequencies
in
adjacent
beams
can
be
reused
by
assigning
vary-
ing
spreading
codes
to
users.

The
method
offers
au-
thentication of
the
source
transmitter
and
is
very
se-
cure
against eavesdropping.
Frequency
reuse
logistics
in
AMPS
and
DAMPS
sys-
tems
are
eliminated
in
CDMA
by
assigning
codes

to
users
so
they
can
share
carrier
frequencies.
The
sys-
tem
capacity
is
not
fixed
but
is
influenced
by
the
ac-
cumulated noise
and
interference associated with
power levels
and
simultaneous
users.
CDMA,
supported

by
companies like Sprint and
PrimeCO,
is
somewhat
similar
to
TDMA,
with
some-
what
less
built-in
support
for
private
branch
applica-
tions.
B-CDMA
is
also
in
development
as
a propri-
etary technology
by
a
group

of
vendors
supporting
InterDigital
Communications.
See
B-CDMA,
spread
spectrum.
Technique
Description
DS-CDMA
Spread
spectrum
technology
in
which
codes
are
used
to
modulate
information
bits
such
that
each
code
is
assigned

to
prevent
the
overlap
of
signals
from
user
to
user.
The
receiver
regenerates
the
code
and
uses
the
information
to
demodulate
the
transmission.
FH-CDMA
A
group
of
changing
frequencies
are

modulated
by
the
information
bits
in
a
two
step
process.
First,
the
carrier
frequency
is
modulated,
and
these
modulated
frequencies
further
modulate
frequencies
while
still
keeping
them
independent.
191
© 2003 by CRC Press LLC