Fiber Optics Illustrated Dictionary - Part 73 docx

Fiber
Optics
Illustrated
Dictionary
Overview
of
Early
OSCAR Satellite Projects
Satellite
Launch Date
Technical Details
Notes
Phase I Satellites - Experimental, Low Orbit, Short Life Span
OSCAR
I
12
Dec.
1961
10
lb,
beacon,
22-day
orbit.
Initiated by a
U.S.
West
Coast group.
Nonrechargeable batteries.
U.S.
Air
Force launched.

OSCAR
II
2
Jun.
1962
Better coatings
and
temper-
Similar
to
OSCAR
I,
but incorpora-
ature control.
ting improvements.
OSCAR
*
Not
launched
Phase-coherent
keying.
Similar structurally
to
previous.
OSCAR
III
9
Mar.
1965
First relay

transponder.
Tracking and telemetry equipment.
Solar backup. Approx.
3000
mi.
range.
18-day transponder
use.
OSCAR
IV
21
Dec.
1965
High altitude, transponder. Unplanned varying elliptical orbit.
Solar,
beacon,
no
telemetry.
Two-way
communication achieved.
Link between Russia and U.s.
OSCAR
5
23
Jan.
1970
Controllable, magnetic
Seven analog telemetry channels.
attitude stabilization. Australis-OSCAR 5
(AO-5).

No
solar
or
transponder. Built
in
Australia.
First NASA-launched
OSCAR.
Phase
II
Satellites - Developmental, Low Orbit, Operational, Longer Life Span
OSCAR
6
15
Oct.
1972
Telemetry,
command,
Twenty-
four
telemetry channels.
transponder.
Two-way
communications.
Solar.
Falsing and beacon problems.
Store-and-forward system. Life
span
exceeded 4 years.
Educational materials printed.

OSCAR
7
15
Nov.
1974
Two
transponders, linear
Many
countries contributed
frequency translation.
various technologies and parts.
Telemetry,
radio
teletype.
AMSAT-OSCAR
7 (AO-7).
Beacons. Relayed with OSCAR
6!
Up
to
4500
miles
low
altitude. Almost 7-year lifespan.
OSCAR
8 5
Mar.
1978
10-m
antenna.

Two
tran-
ARRL
operated. Cooperatively
sponders
(Modes
A &
J)
that
built
by
Project
OSCAR,
AMSAT
could operate simultaneously.
and
JAMSAT.
Lasted 5
years.
Phase
III
Satellites - Operational, High Elliptical Orbit, Longer Life Span (see AMSAT)
712
© 2003 by CRC Press LLC
devices
and
reduced
memory
requirements.
It

was
succeeded
by
OS/2
Warp
Connect which offered
networking
through
full
TCP/IP
capabilities.
OS/2
Warp
version
4
was
aimed
at
corporate
users.
This
version included increased networking features,
speech-to-text
speech
recognition
software,
and
built-
in
support

for
Sun
Microsystems'
Java.
See
Interna-
tional
Business
Machines,
Java,
OS/2.
OS/2
Warp
ServerffiM's
Warp
Connect
system
in-
tegrated
with
their
local
area
network
(LAN) server
4.0.
This
version
of
OS/2

was
designed
for
handling
file
and
device
service
sharing
on
networks.
See
OS/2.
OSCAR
Orbiting
Satellite
Carrying
Amateur
Radio.
A
series
of
orbiting
satellites originally
developed
in
the
homes
and
garages

ofa
group
of
amateur
radio
enthusiasts.
In
1962,
the
OSCAR
Association
was
incorporated
as
Project
OSCAR,
Inc.
The
early
OS-
CAR
satellite
projects
began
in
1961
and
continue
today
in

expanded
and
more
sophisticated
forms.
Early
OSCARs
used
fairly
simple
beacon
transmit-
ters
with
nonrechargeable
batteries,
so
they
were
only
useful
for
a
few
weeks,
but
they
showed
what
might

be
accomplished
with
relatively
simple
materials
and
a
lot
of
cooperative
effort.
Solar
cells
and
telemetry
equipment
were
added
to
later
versions
in
order
to
extend
useful
life
and
provide

greater
control
over
po-
sitioning.
Relays
were
then
added,
with
the
aim
of
eventually
providing
two-way
(bidirectional)
com-
munications.
OSCAR-AMSAT
projects
became
increasingly
so-
phisticated
and,
by
the
time
the

OSCAR
6,
7,
and
8
were
in
orbit,
telemedicine
and
search
and
rescue
sat-
ellite
communications
were
demonstrated
to
be
fea-
sible.
Pioneer
OSCAR
Satellite
The early OSCAR satellites were
put
together in a
cooperative effort out
of

makeshift donatedparts.
yet
were well-conceived. pioneer satellite technologies,
increasing
in
sophistication with later projects. OS-
CAR
III
is shown here.
The
deployment
mechanisms
of
the
early
OSCARs
were
particularly interesting
to
scientists
researching
satellite installation.
The
building, launching,
and
especially
the
tenuous
securement of
domestic

and
international
regulatory
permissions
to
launch
and
op-
erate
were
a
great
achievement
for
amateur
enthusi-
asts,
and
benefits
are
still
accruing
from
the
hard
work
and
voluntary contributions of
radio
amateurs.

See
Overview
of
OSCAR
Projects
chart.
See
AMSAT.
oseE
Organization
for
Security
and
Co-operation
in
Europe.
oscillation
1.
Variation,
fluctuation,
continuing
pe-
riodic
reversal.
Although
oscillation
in
the
general
sense

does
not
imply a regular oscillation,
many
waves,
materials,
and
circuits
studied
or
constructed
by
scientists exhibit
fairly
regular,
predictable
oscil-
lating
properties.
See
quartz.
2.
The
cyclic
alterna-
tion
ofelectrical properties
in
a
circuit.

oscillatorAn electronic
device
designed
to
generate
a low-current alternating current
(AC)
power
at
a
particular
frequency
according
to
the
values
of
cer-
tain
constants
in
its
circuits.
In
microcomputers,
an
oscillator
can
be
used

to
provide a reference
fre-
quency
for
clocking.
An
oscillator
is
also
useful
for
generating
test
signals.
See
oscilloscope,
quartz.
oscilloscope A
device
designed
to
provide
a
visual
representation
of
variations
in
electrical

quantities
as
a
function
of
time,
displayed
in
the
form
of
pulses
or
waves
on
a
monitor.
The
size
and
form
of
the
waves
are
traditionally
tuned
for optimum viewing with
knobs,
as

on
an
old
radio.
Oscilloscopes
are
some-
times
interfaced
with
computers
to
provide
a
means
ofdirectly adjusting
and
analyzing
the
oscilloscope
signals
through
software.
Oscilloscopes
are
useful
for
~~W~:~
~~~~e~~~~ee~e~::~t~~~r(:~~.
the

Open
":.
Group).
OSI
See
Open
Systems
Interconnection.
OSI
Transport
Protocol
OSI
TP.
The
ISO-recom-
mended
communications
protocol
used
by
X/Open.
OSN
1.
operations
system
network.
2.
See
Open
Sys-

tems
Networking
Initiative.
OSP
See
Operator
SelVice
Provider.
OSPF
See
Open
Shortest
Path
First
Protocol.
OSSP
See
Object
Serialization
Stream
Protocol.
OST
Office
of
Science
and
Technology.
AU.K.
gov-
ernment

group
founded
in
1992
to
coordinate
science
and
technology issues across government depart-
ments.
OSTA
See
Optical
Storage
Technology
Association.
OSTP
See
Office
of
Science
and
Technology
Policy.
OT
See
Office
of
Telecommunications.
OTA

Office
of
Technology
Assessment
(U.S.).
OTDR
1.
See
Office
of
the
Director of
Telecommu-
nications
Regulation.
2.
See
optical
time
domain
re-
flectometer.
OTE
The
primary telecommunications carrier
in
Greece.
aTE
is
government-owned.

OTGR
Operations Technology Generic Require-
ments.
OTH
over
the
horizon.
OTN
See
optical transport
network.
OTOHAn
abbreviation
for
"on
the
other
hand"
com-
monly
used
in
email
and
online
public
forums.
See
AFAIK,IMHO.
OTP

1.
See
Office
of
Telecommunications
Policy.
2.
See
Open
Trading
Protocol.
OTU
See
optical
transport
unit.
713
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
OUI
See
Organizationally
Unique
Identifier.
out-bandlout-of-band signaling
Control
signaling

that
is
carried
separate
from
the
informational
por-
tion
ofa
message.
See
Signaling
System
7.
out-of-range alert
In
wireless
communications,
a
beep
or
light
that
alerts
the
user
that
the
handset

is
at
the
edge
of
its
range
and
the
user
shouldn't
move
fur-
ther
from
the
source
of
the
transmission.
outage
Loss
of
power, service interruption.
See
blackout,
brownout.
outlet
1.
Exit,

opening
for
egress,
vent.
2.
Plug
re-
ceptacle
in
a
circuit,
usually
for
electricity
or
con-
nectivity
to
data
transmissions.
3.
Source of
goods,
supplier.
outline font, algorithmic font, vector font A
char-
acter set
defined
by
mathematical algorithms that

describe
the
shape
of
the
letters
with
graphics
primi-
tives
such
as
lines,
arcs,
ellipses,
spline
curves,
etc.
That
way,
when
printed
or
displayed
on
a
monitor,
they
will
be

drawn
at
the
best
possible
resolution
of-
fered
by
the
display
system.
Unlike bitmap
fonts,
which
are
hand
drawn
as
raster
images
that
cannot
be
significantly
reduced
or
enlarged,
vector
fonts

look
good
at
sizes
ranging
from
4
points
to
100
points
and
much
larger.
Outline
fonts
are
resolution-
and
plat-
form-independent,
provided
an
interpreter
is
avail-
able
on
the
system

for
the
particular
format
that
is
being
used.
Since
outline
fonts
are
widely
supported
on
many
platforms,
this
is
usually
not
a
limitation.
output
1.
That
which
results
from,
or

comes
out
of,
a
process
or
system.
2.
The
combined
signal
and
con-
tent
information
ofa
transmission.
3.
The
result ofa
computer
process,
e.g.,
the
output
ofa
word
process-
ing
session

might
be
a printed
document,
Web
page,
or
a
facsimile
transmission.
output
device
A
device
that
facilitates
the
commu-
nication
or
transmission
of
information,
usually
in
another
form
or
format.
In

most
cases,
an
output
de-
vice
is
a
human
interface
in
the
sense
that
it
facili-
tates
the
translation
or
movement
of
information
be-
tween
nonhuman-readable
forms
and
human-read-
able

forms,
or
between
single-copy
modes
and
mul-
tiple-distribution
modes
intended
for
a
wider
audience.
outside plant
OSP.
The
various
outside
structures,
devices,
and
cabling
installations
that
together
com-
prise
a
network.

These
may
be
installed
above
or
be-
low
ground.
Those
supported
by
utility
poles
may
be
termed
aerial.
See
joint
pole
for
utility
pole
informa-
tion
and
diagrams.
outside plant
access

cabinet
OPAC.
Solid,
compact
weather-resistant
cabinets
for
housing
remote-access
network
equipment
and
connections,
usually
in
of-
fice
and
industrial
park
environments.
The
cabinets
may
be
controlled
for
factors
such
as

temperature
and
humidity
in
order
to
protect
sensitive
electronic
com-
ponents
and
are
usually
designed
to
deter
vandalism.
Besides
leaving
more
space
free
inside
the
building,
the
outside
access
cabinet

makes
it
possible
for
main-
tenance
personnel
to
access
the
devices
without
en-
tering
the
building
premises.
outsourcing
The
process
of
assigning
production
or
management
tasks
to
an
external
consultant

or
organi-
714
zation. Outsourcing is practical when special
expertise
is
needed,
or
the
project
is
short
and
hiring
new
permanent
staff
would
be
impractical.
Special-
ized
design
projects,
advertising,
documentation,
and
cyclic/seasonal projects
are
often outsourced.

Net-
work
administration
is
often outsourced
by
small
companies,
whereas
a
company
with
alarger or
more
complex
network
would
probably
have
an
in-house
system
administrator.
Telephone
answering
services
are
a
common
form

of
outsourcing
used
by
small
businesses
and
home
busi-
nesses.
Utilizing
an
answering
service
is
less
expen-
sive
than
hiring a receptionist - a
good
solution
for
small
companies
that
don't
receive
a
lot

of
incoming
calls.
OutWATS
Outward
Wide
Area
Telephone
Services.
A
WATS
service
for
outgoing
calls,
which
is
avail-
able
at
bulk-use
discounts.
See
InWATS,
WATS.
OV2-5
Aresearch satellite
designed
to
measure

so-
lar
and
cosmic
rays
and
magnetic
influences.
It
was
launched
in
September
1968
into
a circular
equato-
rial
orbit
at
an
altitude
of
22,000
miles.
A
model
of
the
OV2

was
donated
to
the
U.S.
Air
Force
Museum
by
the
Northrop
Corporation.
overcoat-incident recording
OCIR.
A
new
technol-
ogy
for
recording
optical
storage
media
that
permits
higher density
data
per unit
area
than

previous
meth-
ods
such
as
substrated-incident
recording.
Tradition-
ally,
optical
discs
have
used
a
substrate
laid
down
over
the
recording
surface
to
protect
the
data
from
abra-
sions,
contamination,
and

oxidation.
This
limited
the
areal
density
of
the
recorded
information.
OCIR
technology
was
developed
by
Maxoptix
(trade-
marked
as
OverCoat
Incident
Recording
with
patents
pending).
In
OCIR,
the
recorded
information

is
im-
printed
on
top
of
the
substrate (similar
to
hard
disk
media)
and
then
covered
with
a protective layer of
acrylic
that
is
much
thicker
than
hard
disk
and
tape
recording
media,
but

thinner
than
standard
optical
recording
substrates.
Thus,
the
lens
can
be
positioned
closer
to
the
recording
surface,
realizing ahigher
nu-
merical
aperture
(NA)
for
recording
at
higher
data
densities.
Maxoptix's
goal

was
to
realize
40.GBytes
of
recorded
data
at
30
Mbps
transfer
rates.
See
air-
incident
recording,
substrate-incident
recording,
sur-
face-array
recording.
overflow
1.
Traffic
or
data
in
excess
of
what

is
typi-
cally
found
on
a
system,
or
in
excess
of
what
the
sys-
tem
is
capable
of
handling.
Some
systems
have
ad-
ditional
or
alternate circuits,
lines,
systems,
or
opera-

tors
to
handle
overflow,
while
others
may
be
slowed
down
in
terms
of
speed
of
service,
or
may
cease
to
function.
2.
In
telephone
circuits,
overflow
traffic
may
be
diverted

to
another
trunk
line.
See
erlang.
overflow,
data
In
programming,
an
overflow
occurs
when
an
operation
generates
a
result
for
which
there
is
insufficient
address
or
storage
space.
overhead
The

portion
of a
task,
data
block,
or
op-
eration
that
provides
management
informafion
per-
taining
to
the
task,
data,
or
operation,
which
is
not
part
of
its
integral
content.
For
example,

the
overhead
in
a
graphics
file
may
consist
of
a
header
containing
© 2003 by CRC Press LLC
size
and
palette
information,
which
is
not
part of
the
image
itself.
The
overhead
in
a parallel processing
operation
may

be
the
time
and
processing
it
takes
to
handle
the
logistics
of
farming
out
the
tasks
and
re-
combining
the
results
of
the
processes.
In
networks,
overhead
exists
in
the

form
ofprotocol
information,
timing
infonnation, error
data,
security
bits,
routing,
priority,
and
more.
Given
the
amount
of
overhead
in
networks,
it's
a
maIVel
that
they
can
work
so
effectively.
overhead transparency, foil Atransparent
medium

receptive
to
photocopy
toner
or
various
inks
which
is
used
in
conjunction
with
abright
light
and
projec-
tor
to
project
information
on
a
large
surface
such
as
a
screen
or

plain
wall.
Overhead
transparencies
are
often
used
for
presen-
tations, especially
to
illustrate lectures. Overhead
transparency
films
come
in
a
variety
of
compositions;
some
can
be
photocopied
in
black
and
white,
some
in

color.
Don't
use
regular transparency paper
in
a
laser
printer
or
photocopier,
as
the
plastic
may
melt
and
destroy
the
internal mechanisms. Cardboard
frames
can
be
purchased
to
support
the
transparen-
cies,
which
are

somewhat
flimsy
and
otherwise
hard
to
hold
and
organize.
overlay
1.
n.
A
keyboard
template
or
sheath.
See
key-
board
overlay.
2.
n.
A
template,
grid,
pattern,
image,
or
other

reference
information
superimposed
over
a
field
of
view.
Overlays
are
used
to
measure,
count,
estimate,
asses,
evaluate,
and
embellish
the
informa-
tion
or
environment
over
which
they
are
used.
See

optical
combiner,
projected;
graticule;
reticule.
3.
v.
In
programming, a technique
in
which a limited
amount
of
storage
is
extended
by
reusing portions
which
are
not
immediately
or
subsequently
required,
or
by
initiating
less
commonly

used
routines
only
on
demand.
In
telephone
applications,
overlays
may
be
used
to
bring
various
tasks
into
memory
as
needed.
Some
versions
of
BASIC have commands (e.g.,
LSET)
which
allow
a variable
in
RAM

to
be
over-
written
with
a
subsequent
variable
in
order
to
prevent
eventual
slowdowns
from
garbage
collection,
that
is,
from
the
reorganization
of
storage
to
accommodate
more
information.
overlay
area

code A
telephone
area
code
assigned
as
a
parallel
code
in
an
existing
service
area.
These
are
commonly
assigned
to
mobile
services,
like
cel-
lular
and
pager
services,
so
that
the

area
code
is
sepa-
rate
from
the
geographic
code
assigned
to
that
region.
These
are
not
yet
prevalent,
but
are
expected
to
in-
crease
as
mobile
services
are
more
widely

distributed.
See
North
American
area
codes
for
a chart of
tele-
phone
and
mobile
service
area
codes.
overlay networkAprotocol
or
application-specific
subnetwork,
managed
and
configured
independently
of
its
underlying
infrastructure,
and
interconnected
by

Internet
Protocol
(IP)
encapsulation
tunnels
over
production
networks.
Recent
protocols
are
supported
on
overlay
networks,
including
Mbone
(multicast
IP)
and
6bone
(IPv6).
overlay, video
In
video
editing,
it
is
common
to

over-
lay
two
video
signals,
or
to
overlay a
computer
sig-
nal
over
a
video
signal,
or
vice
versa.
Newscasts
will
often
overlay
a
human
weather
forecaster
over
a
com-
puter-generated

weather
map.
In
cinema
action
shots,
a
stunt
worker
in
a
barrel
may
be
overlaid
on
an
im-
age
of
the
Niagara
Falls.
See
chromakey.
override
1.
To
overlap,
neutralize,

take
over,
domi-
nate.
Astronger
signal,
such
as
an
emergency
signal,
can
override
aregular
transmission.
A
boss
can
over-
ride
the
decision of a
subordinate;
a priority
trans-
mission
can
override
current
transmissions.

An
op-
erator
can
override a current
phone
conversation.
Some
private
branch
phone
systems
are
configured
so
that
someone
in
authority
has
the
option
of
over-
riding
other conversations, a
power
that
should
be

used
with
discretion.
overrun
To
overwhelm,
to
swarm,
to
go
above
or
beyond
an
edge
or
capacity,
to
overflow.
A
cost
over-
run
happens
when
someone
goes
over
budget
or

some
other
allotted
quantity.
A
data
overrun
can
happen
when
the
receiving
system
isn't
fast
enough
or
smart
enough
to
handle
the
incoming transmission. A
printer
overrun
can
happen
if
the
print

mechanism
continues
to
function
after
the
paper
runs
out
(some
facsimile
machines
still
do
this).
Overruns
often
re-
sult
in
discard
or
loss
of
information.
See
cell
rate,
leaky
bucket.

oversamplingA
process
of
redundant
sampling
used
in
some
multiplexing
schemes.
overscan,full scanAn
image
output
to
a
monitor
that
extends
to
the
maximum
outer
extents
of
the
cath-
ode
ray
tube
(CRT)

or other
scanning
display
device.
Overscan
on
computers
may
be
achieved
by
increas-
ing
the
resolution of
the
display
or
by
adjusting
po-
sition
and
size
controls
associated
with
the
display
device.

Overscan
display
modes
are
common
in
video
applications,
where
the
signal
is
not
being
optimized
for
the
computer
monitor,
but
for
the
video
record-
ing
medium
to
which
it
is

being
output.
Overscan
may
also
be
a screen option
on
some
systems that
are
adapted
for
desktop
video
and
usually
adds
about
10
to
30
pixels
to
each
edge
of
the
displayable
resolu-

tion.
(Thus,
a
320
x 480-scanline interlaced
image
might
become
360
x
525
scanlines
in
overscan
mode,
for
example.)
Flat
screen
monitors
are
becoming
more
widely
avail-
able,
but
in
the
past,

cathode
ray
tubes
had
asignifi-
cant
curvature
at
the
outer
edges
which
would
dis-
tort
the
image
(like looking
through
a
lens)
at
the
outer
edges.
In
order
to
minimize
distortion,

the
im-
age
is
usually
not
displayed
to
its
fullest
extent,
but
rather
to
the
point
on
the
front
of
the
tube
at
which
the
curve
begins.
The
edge
of

the
monitor
casing
is
usually
designed
by
the
manufacturer
to
fall
approxi-
mately
at
the
same
point
or slightly
outside
the
point
at
which
the
overscan
image
falls.
See
cathode
ray

tube.
overshoot
In
general
terms,
atransmitted
signal
that
travels
to
some
point
beyond
the
receiver
(too
far,
too
high,
at
too
high
a
frequency,
etc.)
or
a
receiving
sys-
tem

that
over-responds
to
a
stimulus
signal.
Over-
shoot
may
be
a compensatory
strategy,
an
undesir-
able
condition, or a
manageable
condition (e.g.,
it
may
be damped or otherwise moderated). The
715
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
converse
is
undershoot.

Fiber
optic
sensor
probes
can
help
prevent
undesired
temperature
or
humidity
overshoot
in
fabrication
or
controlled
environment
processes.
At
the
same
time,
while
fiber
optic
probes
may
be
useful
in

preventing
overshoot
in
fabrication
processes
they
may,
them-
selves,
be
subject
to
overshoot
if
they
are
held
too
near
the
object
probed
such
that
a
resonant
frequency
amplifies
the
probe

signal
and
gives
an
incorrect
reading.
In
electronic
logical
circuits,
a
derivative
function
may
be
used
to
assess
the
rate
of
change
in
a
system
to
send
an
alarm
or

automatically
adjust
a
component
to
halt,
minimize,
or
reduce
overshoot.
In
more
specific
terms
in
optical
communications,
overshoot
is
an
undesirable
excess
occurring
as
the
result
of a
transition
of a
signal

from
one
phase
or
signal
level
or
type
to
one
that
is
lower.
Thus,
exces-
sive
amplitude
in
a
waveform
beyond
what
is
desired
in
a
nonsinusoidal
wave
results
in

overshoot
in
fiber
optic
links.
See
hysteresis,
optical
eye
pattern
mea-
surement
procedure.
overtime period
In
a
pay-per-time-connected
ser-
vice,
the
time
that
elapses
after
the
paid-up
period
has
been
exceeded.

When
using
a
payphone,
the
time
af-
ter
the
initial
insertion
of
coins
has
run
out
is
over-
time,
and
the
operator
may
request
additional
funds
or
terminate
the
call.

The
same
general
idea
applies
to
per-pay
network
access,
time-sharing,
or
any
other
system
in
which
a
set
amount
of
time
is
billed
periodically,
or
is
pre-
paid,
with
the

option
for
the
user
to
exceed
the
usage
period
as
long
as
additional
fees
are
paid,
often
at
a
higher
rate.
716
overtone
In
wave
phenomena
that
can
be
character-

ized
as
sinusoidal,
an
integral
multiple
of
the
wave
frequency,
a
resonant
harmonic,
a
combination
vibra-
tion.
Overtones
may
be
numbered;
the
first
overtone
is
twice
the
frequency
of
the

fundamental
reference
frequency.
Musicians
are
familiar
with
audible
overtones.
For
example,
on
a
violin,
high-pitched
overtones
may
be
generated
by
bowing
a
string
at
a
certain
resonant
vi-
brating
frequency

such
that
the
overtones
can
just
be
heard
over
the
main
note.
Light-based
phenomena
also
exhibit
overtones.
In
spectroscopy, absorption frequencies
may
exhibit
multiple
harmonic
overtone
bands.
As
these
bands
become
more

removed
from
the
fundamental
refer-
ence
frequency,
they
progressively
become
more
widely
separated
and
lower
in
intensity.
In
near-in-
frared
spectroscopy,
the
strongest
absorption
bands
usually
occur
in
the
first

and
second
overtones.
OVS
See
Open
Video
System.
OWT
Operator
Work
Time.
axe
See
optical
cross
connect.
oxidation
The
process
of
combining
with
oxygen,
often
resulting
in
a
significant
change

in
the
material
oxidized
that
may
degrade
or
otherwise
influence
its
integrity
or
usefulness
for
aparticular
purpose.
Oxi-
dation
is
a particular
concern
in
external
wiring
in-
stallations
or
cables
exposed

to
water
or
chemicals.
See
corrosion.
oxymoron
A
combination
of
contradictory,
incon-
gruous
words.
Puns
sometimes
have
oxymoronic
im-
plications
which
mayor
may
not
be
true.
Satirical
ex-
amples
include:

common
sense,
military
intelligence,
casual
dress,
friendly
frre,
and
authentic
reproduction.
© 2003 by CRC Press LLC
P
1.
symb.
pico
2.
abbrev.
power.
P
1.
symb.
penneance.
2.
symb.
peta
3.
abbrev.
phos-
phorus.

p connectorApower connector
commonly
used
for
attaching
internal
computer
peripherals
such
as
floppy
drives,
hard
drives,
CD-ROM
drives,
etc.
Computer
power
connectors
are
largely standardized
as
4-pin,
keyed
connectors.
(In
the
late
1970s

and
early
1980s,
they
weren't
always
keyed.)
It
is
preferable
to
call
this
apower
connector
to
prevent ambiguity with 68-pin
P
connectors.
See
Pconnector.
Standardized Peripheral Power Connector
A typicalpowerconnectorfor computerperipherals
such
as
hard
diskdrives standardized
as
(A)
+12 volts

-
yellow,
(B
&
C)
ground -
black,
(D)
+5 volts -
red.
Unlike
earlier
connectors,
they
are
now
typically keyed
(notched
on
one
side)
to
prevent incorrect
connections.
P connector
1.
An ANSI-standardized 68-pin elec-
trical
data
connector commonly

used
for
8-and
16-
bit
data
buses
for
computer peripherals
such
as
SCSI
drives,
especially SCSI-3,
as
a P connector
can
sup-
port
wide
bus,
high-density data transmissions.
The
Very
High Density
Cable
Interconnect
(VHDCI)
con-
nector

is
an
Alternative 4 P connector with
the
same
pinouts
as
the
68-pin connector,
but
it enables
mul-
tiple SCSI connectors to be connected to one
backplate.
See
A
connector.
2.
See
Polaroid
connector.
p region In semiconductor component theory
and
engineering, a region
in
which
the
conduction-elec-
tron
density characteristics result

in
positive "holes"
that
can
be
exploited
for
their dynamic interactive
characteristics.
The
p region
is
related
to
n materials
in
the
n region, where conduction-electron density
exceeds
hole
density.
See
n region, p-n junction.
PSeries Recommendations Aseries
of
ITV-
T
rec-
ommended guidelines
for

telephone transmissions
quality,
installations,
and
local phone line
networks.
They are available
for
download
from
the
ITV-T.
Since
lTV
-Tspecifications
and
recommendations
are
widely followed
by
vendors
in
the
telecommunica-
tions
industry,
those wanting
to
maximize interoper-
ability with other

systems
should
be
aware
of
the
in-
fonnation disseminated by
the
ITV-
T.
A
full
list of
general categories
is
in
the
Appendix
and
specific
se-
ries
topics
are
listed under individual entries
in
this
dictionary,
e.g.,

M
Series
Recommendations.
See
P
Series Recommendations chart.
P-47 A commercial cesium-doped yttrium silicate
(Y
SiO
s
)
powder
with
a
fine
grain
for
fabricating
scin-
tilrating
discs
with
fast
delay
times.
In conjunction
with
an
appropriate suspension liquid
and

binder,
the
powder
can
be
used
to
coat a glass substrate
with
a
unifonn layerwhich
is
then baked
for
about
12
hours
to
produce a scintillating layer that
can
be
combined
with
a
variety
of
imaging
components.
See
scintillator.

P-frame predictive-coded
frame.
In
MPEG
anima-
tions,
a picture which
has
been encoded
into
a video
frame
according
to
information extrapolated
from
past
frames
in
the
sequence, using predicted motion
compensation algorithms. See B-frame, I-frame,
MPEG
decoder.
P-picture predictive-codedpicture. In
MPEG
anima-
tions,
apicture that
is

to
be
encoded
according
to
past
frames
in
the
sequence using predicted
motion
com-
pensation algorithms.
Once
it
is
encoded,
it
is
con-
sidered
to
be
a P-frame.
See
MPEG
decoder.
P-T pressure-temperature.
PIB
peak

to
background (ratio).
P3P
See
Platfonn
for
Privacy.
pA
abbrev.
picoampere.
Pa
1.
abbrev.
pascal.
2.
abbrev.
protactinium.
PA
1.
preliminary assessment.
2.
See
public address
system.
PABX
See
Private Automatic Branch
Exchange.
PACA
1.

See
Pacific
and
Asian Communication
As-
sociation.
2.
Picture Agency Council of
America.
A
trade
organization supporting stock
image
agencies
in
North America. .
3.
See
Priority Access
and
Channel Assignment.
717
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
ITU-T
P Series
Recommendations

Telephone
transmission
quality,
telephone
installations,
local
line
networks
P.I0 Vocabulary
of
terms
on
telephone
transmission.
quality
and
telephone sets
P.ll Effect
of
transmission impairments
P.16
Subjective·
effects
of
direct crosstalk;
thresholds
of
audibility and
intelligibility
P.30

Transmission perfonnance
of
group
audio·
tenninals
(GATs)
P.32
Evaluation
of
the
efficiency
of
telephone booths and acoustic hoods
P.33
Subscribertelephonesets containing
either loudspeaking.receivers or
microphones associated
with
amplifiers
P.35
Handset telephones
P.36
Efficiency
of
devices for.preventing
the
occurrence
of
excessive acoustic
pressure

by
telephone receivers
P.38
Transmission characteristics
of
operator
telephone systems (OTS)
P.48
Specificationfor
an
intermediate
reference.
system
P.SO
Test
signals
P.51
Artificial mouth
P.S2
Volume
meters
P.S3
Psophometer for use
on
telephone-type
circuits
P.54
Soundlevel meters (apparatus for
the
objective measurement

of
room noise)
P.SS
Apparatu$
for
the
measurem~nt
of
impulsive noise
P.S6
Objective measurement
of
active speech
level
P.S7
Artificial ears
P.S8
Head and torso simulator for
telephonometry
P.S9
. Artificial conversational speech
P

61
Methods
for
.
the
calibration
of

condenser microphones
P

62
Measurements on subscribers' telephone
equipment
P

63
Methods
for
the evaluation
of
transmission quality
on
the basis
of
objective measurements
P.64
Determination
of
sensitivity/frequency
characteristics
of
local
telephone
systems
P.65
Objective instrumentation for the
determinatioD.ofloudness ratings

P.66
Methodsfor evaluating the transmission
perfonnanceofdigitaltelephone sets
P.75
Standard conditioning method for
handsets withcarbon.microphones
718
P.76
P.78
P.79
P.82
P.84
P.85
P.310
P.311
P.313
P.340
P.341
P.342
P.3S0
P.360
P.370
P.SOI
P.502
P.S61
P.S62
P.581
P.800
P.810
P.830

P.831
Determination
of
loudness
ratings;
fundamental.
principles
Subjective testing method
for
determination
of
loudness ratings
in
.
accordance with Recommendation
P.76
Calculation
of
loudness ratings
for
telephone
sets
Method
for
evaluation
of
service
from
the
standpoint

of
speech transmission
quality
Subjective listening test method
for
evaluating digital circuit multiplication
and packetized voice systems
A method
for
subjective performance
assessment
of
the quality
of
speech
voice output devices
Transmission characteristics for
telephone-band (300
to
3400Hz) digital
telephones
Transmission characteristics for
wideband
(1
SO
to
7000
Hz) digital
handset telephones
Transmission characteristics

for cordless
.and mobile digital terminals
Transmission characteristics
of
hands-
free
telephones
Transmission•characteristics
for
wideband (150 to
7000
Hz)
digital
hands-free telephony terminals
Transmission characteristics
for
telephone band (300
to
3400 Hz) digital
loudspeaking and hands-free telephony
terminals
Hands~t
dimensions - formerly.ITIJ-T
P.35
,
Efficiency
of
devices for preventing the
occurrence
of

excessive acoustic
pressure
by
telephone receivers
Coupling.hearing aids to telephone sets
Test signals for use
in
telephonometry
Objective test methods for speech
communication systems
using
complex
test signals
In-service nonintrusive measurement
device - voice service measurements
Analysis and interpretation
of
INMD
voice service measurements
Use
of
bead and torso simulator
(HATS)
for
hands-free terminal testing
Methods
for
subjective determination
of
transmission quality

Modulated noise reference
unit
(MNRU)
Subjective performance assessment
of
telephone-band and wideband digital
codecs
Subjective performance evaluation
of
network echo cancellers
© 2003 by CRC Press LLC
Supplements
Telephone
transmission
quality,
telephone
installations,
local
line
networks,
cant.
P.Supl
Preciu.ltions
to
be.taken forcorreet
instanation
and
maintenance
of
an

IRS
pJst!Pio
Y~11sideratiol1st~l~tirlg.to
•
ttattstnissioncltaraeteristics
for
analogue
handsettelephones
P.Stlp14
Subjective
performance assessment
of
digital processes using the modulated
noise reference unit
(MNRU)
P.Sup
15
Wideband
(7kHz)
moduJatednoise
reference
unit (MNRU) with
noise
shaping
P.Sup16
Oui~Hnes
forplacement
of
microphones.
and

loudspeakers in
telephone
conference
rooms
and
for
Gr~l.lpAudioTen:ninals
(G~Ts)
P.Sttp.l
••
7
Direct.·
.•
l()u~.es~.·
••
~latt.c~
••••
agaill~
••
·.tbe
interr.nediate
referertcesystem (IRS)
for
the subjective detenninationof
loudness ratings
P.Sup19
Information
on
some loudness loss
related ratings

P.Sup20
Examples
of
measurements
of
handset
receive-frequency
responses:
dependence
on
earcap leakageJosses
P.Sup22
Transmission
characteristics
•.
of
wideband audio
telephones
P.Sup23
ITU-T coded-speech database
Pacific
and
Asian
Communication
Association
PACA.
A nonprofit educational, literary,
and
scien-
tific

organization
founded
in
March
1995.
PACAsup-
ports
and
promotes
the
research, criticism,
and
ap-
plication
of
artistic, humanistic,
and
social scientific
principles
of
communication.
PAC
A publishes
the
journal
Human
Communication,
and
sponsors
vari-

ous educational workshops and conferences.
/>pack
To
compact characters or
data
together
to
con-
serve
space,
usually
by
removing
spaces
and
any
other
unneeded
characters. In
the
old 4-kilobyte comput-
ers
from
the
1970s
that
used
BASIC
as
a

program-
ming
language, "string packing"
was
a
means
to
save
precious
memory.
Database entries
and
email
messages
often
have
a
lot
ofempty
space
in
them
and
so
may
be
packed
to
re-
duce

the
storage
size
of
files.
Packing
is
a
simple
fonn
ofcompression.
See
compression.
Packard,
David (1912-1996) American business-
man,
philanthropist,
and
founder,
along
with
William
Hewlett, of
the
Hewlett-Packard computer
company,
one
of
the
well-respected pioneering

companies
of
the
computing
industry.
The
company had
its
humble
be-
ginnings
in
the
Packard garage
in
Palo
Alto,
Califor-
nia,
and
has
grown
into
amultinational
company
with
over
100,000
employees.
Packard

also
cofounded
the
American
Electronics Association,
and
was
a
mem-
ber
of
the
President's Council
of
Advisors
on
Science
and
Technology for 4 years. Hewlett, William
R.;
Hewlett-Packard.
PackedEncodingRules
PER.
Developed
in
the
early
1990s,
PER
is

one
of
three
major encoding
schemes
used
in
open
architectures
development.
Unlike
BER,
tags
are
ignored
and
length fields
may
be
omitted.
PER
provides a means for creating more succinct
encodings optimized
for
bits
on
the
line
and
gener-

ally
has
lower bandwidth requirements
than
BER
or
LWER.
See
Basic Encoding Rules, LightWeight
En-
coding
Rules.
packet
1.
A generic tenn
for
a unit
of
data
fonned
as
a
bundle
with
acertain specified
organization,
accord-
ing
to
a

protocol.
Other
designations
for
network
units
and
bundles include
cell
and
frame.
Although packet
fonnats
vary,
they
most
typically include a
header,
an
infonnation
payload,
and
a
trailer.
The
header
may
contain anumber
of
pieces

of
infonnation, including
priority,
source,
destination, length of
packet,
etc.
The
payload
is
the
message
or infonnation being
sent,
and
may
be
split
over
a
number
of
packets.
The
trailer
may
include
flags,
signals,
and

error detection
or
correc-
tion
data.
When
a series ofrelated packets
is
trans-
mi
tted
over anetwork, they
may
not
all
take
the
same
route,
and
so
disassembly,
routing,
and
assembly
pro-
cedures
may
be
applied

to
transmitted packets;
in-
structions
to
coordinate this process mayor
may
not
be
included
in
some
of
the
packets.
Sometimes
packet-switched networks
are
connected
to
non-packet-switched networks, in which case
tunneling takes place, or conversion through a
packet assembler/disassembler,
to
accommodate
the
differences
in
formats.
Subjective

perfonnance evaluation
of
hands-free
terminals
Methodology
forderivation~f
equiPl\1entim~~ent
f~cto~I:r0tt1
subjective··
••
liste~ing-onlY.test~.:.;
•••
:
•••
:
Objective
quality·measuremetttof
telephone-band (300 to 3400Hz)
speech
codecs
PercetJtual
evaluation
of
speech
quality-
(PESQ),
an
objective method
for
end-to-end

speech
quality
assessment
of
narrowband telephone
net\Vorks
and speech cadecs
Subjective
videoqualityasse~~ent
methods for multimedia applications
Subjective
audiovisual
quality
assessment
methods
for
multimedia
ap~li~~~ns.\/
.•.
Interactive testmethOds for
audiovisual.
communications
Principles
of
a reference impainnent
syste1T1for
video:
. .
Multimedia
C011lD1wUriations

delay,
synchronization
and
frame
rate
measurement
P.833
P.910
P.861
P.832
P.862
P.93
0
P.931
P.920
B911
719
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
packet assembler/disassembler
PAD.
In
packet-
based systems, information
is
converted into data
units

known
as
packets,
and
then
transmitted.
At
the
receiving
end,
these
packets
are
apprehended
and
dis-
assembled
to
tum
them
back
into
the
information
con-
tained
in
the
original content.
packet fIltering

The
evaluation ofpacket structure
or
contents
in
order
to
selectively
reject
or
accept
pas-
sage
of
the
packet through a network junction.
See
fIrewall.
packet radio Packet
radio
is
a combination of
com-
puter equipment
and
radio transmissions used
to
ex-
change
messages.

Microcomputers
and
terminal
node
controllers
(TNCs)
are
commonly
used
in
packet
ra-
dio
systems.
The
computer
is
cabled
to
a
radio
trans-
ceiver
at
each
end
of
the
communication. Because
computers

have
store
and
forward,
or
other
types
of
scheduling capabilities,
the
operator doesn't
have
to
be
present
when
the
message
is
sent
or received.
In
radio,
this
is
called
time-shifted
communications.
The
system

could
be
configured
to
send
at
a
time
when
interference
is
less
likely
to
be
encountered, or
when
a
favorable
time
of
day
occurs
at
the
sending or
re-
ceiving
end.
Packet

radio
transmission
speeds
are
fast
enough
that
various
types
of
propagation
can
be
used, including
meteor-scatter.
Due
to
the
nature ofpacket transmis-
sion
and
its
built-in error-correcting mechanisms,
packet transmissions
are
reliable. Packet
radio
uses
a number ofprotocols
and

favors
the
Open
Systems
Interconnection (OSI) reference model. Common
protocols
in
use
include
NETIROM,
AX.25,
TCP/IP,
and
ROSE.
packet reservation multiple
access
PRMA.
An
en-
hanced
time
division
multiple
access
(TDMA),
which
incorporates aspects of
S-ALOHA.
It
is

suitable
for
mobile transmissions.
See
ALOHA,
time division
multiple
access.
packetsnifferA
diagnostic
and
snooping
mechanism
for
examining
the
contents
of
network packets
dur-
ing
transmission.
See
packet
tracing.
packet
switched
radio
See
packet radio.

packet
switching
Acomputer communications
tech-
nology
developed
in
the
early
1960s
that bundles
up
information
into
discrete
data
packets which
can,
be
sent out
in
separate paths,
like
breaking
up
the
cars
on
a train sending
them

on
separate tracks,
and
put-
ting
them
all
back together
again
at
the
destination.
In
the
1960s,
computing
was
becoming
more
acces-
sible,
generating
greater
interest
in
its
use
and
spurring
the

manufacture
ofvarious
types
of
systems.
Practi-
cal
packet-switched
implementations
began
to
appear
in
the
1970s,
and
separate
server
computers
to
handle
various specialized purposes,
such
as
accounting,
opened
the
doors
to
the

development
of
various
types
ofdistributed
computing
architectures.
The
rise
of
ARPANET
greatly influenced
the
devel-
opment
and
acceptance
of
packet switching.
With
hosts
springing
up
in
distant locations
and
special-
ization
and
the

variety
of
computing tasks increas-
ing,
packet switching
was
a practical way
to
facili-
tate intercomputer communications.
720
Gradually,
layered architectures emerged, separating
user functions
and
applications
from
lower level
op-
erating functions.
This
enabled information carried
in
packets
to
be
communicated through
many
differ-
ent

types
of
systems, while still retaining
the
unique
operating
features
and
user interfaces
of
each
system.
Historically, telephone networks were built around
circuit-switching.
This
meant that a dedicated path
through
the
switching system had
to
be
established
(and
was
tied
up)
for
the
duration
of

the
call.
In
a
large
global network
where
many
institutions
are
online all
the
time,
this
is
not apractical solution. Abetter way
for
large systems
is
to
route information through
whatever
path
is
most
practical
at
the
time
(since

some
systems
may
be
inaccessible
or
offline without
no-
tice),
to
divide
the
packets
up,
if
necessary,
if
routes
change
while the
data
are
en
route,
and
to
resend any
portions
of
the

message that don't
make
it
through. It
works
24
hours a
day,
and
will continue
to
try
to
send
the
data
in
adynamically
changing
environment,
even
if
intermediate hosts
or
the
receiving party
are
tem-
porarily
offline.

This
essential
flexibility
is
at
the
heart
ofpacket-switching architectures
and
is
incorporated
into
huge
cooperative systems like
the
Internet.
See
circuit
switching,
Open
Systems
Interconnection,
Systems
Network Architecture,
X.25.
packet switching network A communications net-
work
in
which achannel
is

occupied
only
for
the
time
during
which
the
packet, a unit
of
data,
is
transmit-
ted,
a
common
distributed
data
network
format.
See
Frame
Relay.
packet tracing
See
packet
sniffer.
pad connector Short
for
touchpad

connector.
Acon-
nector that enables
atouchpad keyboard
(with
a flat
surface rather than raised keys) or other flat input
configuration
to
be attached
to
an
electronic device
(usually a computer or kiosk terminal).
PAG
See
Producers Advocacy
Group.
page
description language
POL.
A
means
ofprovid-
ing
commands
to
a
system
for

the placement and
for-
matting
of
page elements, such
as
text
and
graphics.
Adobe
PostScript
is
widely used, powerful page
de-
scription language,
and
HTML
is
a very
basic
page
description language extensively used
to
format
in-
formation
for
viewing with a
Web
browser.

Various
printers
include
page
description
languages
which
are
usually somewhere between PostScript
and
HTML
in
complexity.
pager
1.
A general broadcasting loudspeaker con-
nected
to
a phone
or
microphone, usually
in
a busi-
ness, or educational or health care institution. See
public address
system.
2.
Aportable, wireless hand-
held device which
can

emit
an
audible, short verbal
message or short alphanumeric
message.
These
are
often used
by
emergency workers,
sales
representa-
tives,
and
business professionals.
See
paging.
pagingAlerting arecipient that
there
is
a
message
or
item
awaiting
his
or
her
attention. Public
address

sys-
tems
can
be
used
to
page
employees
or
clientele
when
packages are
ready,
when there
is
a
phone
call, or
when lost children or items have been located or
turned
in.
Pagers
commonly
known
as
beepers
are
© 2003 by CRC Press LLC
portable
wireless

devices
that
will
make
an
audible
beeping
sound
to
signal
that
a
message
or
call
is
wait-
ing,
or
that
the
user
has
to
go
to
a
certain
location
if

paged.
Portable
wireless
alphanumeric
pagers
can
dis-
playa
short
message
or
telephone
number
to
notify
the
user
ofa
situation
or
phone
message.
Pagers
are
commonly
used
by
professionals
in
the

field,
emer-
gency
workers,
and
industrial
yard
workers.
See
pub-
lic
address
system,
Short
Message
Service.
pagingsystem
PSI
A
system
which
allows
a
message
to
be
broadcast
broadly
to
anyone

wi
thin
range
of
the
speaker,
usually
to
attract
the
attention ofa particu-
lar
person
or
party,
to
give
instructions,
or
to
ask
someone
to
pick
up
a
message.
Paging
systems
are

common
in
hospitals,
schools,
and
shopping
malls.
See
public
address
system.
pair
A
pair
of
associated
wires,
often
twisted
together
to
facilitate
electrical conductance and/or
to
reduce
noise.
Most
phone
networks
are

based
upon
decades-
old
circuits
of twisted-pair
copper
wires.
A pair of
cables
is
used
in
a
number
of
multimedia
schemes,
wi
th
one
carrying
sound
and
the
other
graphics,
or
one
carrying

sound
and
graphics
data
while
the
other
carries
timing
information.
pair
assignment
The
assigning ofa
specific
current,
transmission,
or
function
to
a
twisted-pair
wire.
These
are
often
designated
with
a
code

or
color,
in
order
to
make
interconnections
quicker
and
less
error-prone.
PAL
1.
See
phase
alternate
line.
2.
See
programmable
array
logic.
PALC plasma-addressed liquid crystal.
See
liquid
crystal
display,
plasma
display
panel.

Paley, William S.
An
American experimenter
and
business
tycoon
who
purchased
and
developed
the
Columbia
Phonograph
Broadcasting
System
(1927)
into
the
Columbia
Broadcasting
System
(CBS)
in
1928.
Under
his
leadership,
the
company
grew

and
added
new
products
and
services
to
its
line.
In
1983
Paley
retired
from
CBS,
only
to
return
3
years
later
to
work with Lawrence Tisch.
In
1995
CBS
was
bought
by
Westinghouse.

In
1975,
Paley
established
the
Museum
of
Television
and
Radio
in
New
York,
an
educational
resource
and
archive
of
historical
and
culturally
important
broad-
casts.
The
William
S.
Paley
Foundation,

Inc.
has
been
established
in
his
honor.
Palo Alto Research
Center
PARCo
One
of
several
Xerox
research
installations,
PARC
was
founded
in
1970
in
the
Stanford
University Industrial
Park.
It
is
the
site

of
many
remarkable
pioneer
developments
in
the
field
of
computers
and
telecommunications.
The
PARC
was
a
hotbed
in
the
1970s
for
many
original
developments
in
object-oriented
programming
and
computer
interface

design.
Both
Apple
and
Microsoft
toured
the
facility
in
their
early
days
and
were
inspired
by
their experiences there, particularly demon-
strations
of
the
Alto computer running Smalltalk
applications.
See
Kay,
Alan;
Smalltalk.
PAM
1.
payload
assist

module.
Ashuttle satellite
de-
ployment
mechanism.
The
satellite
in
this
context
is
considered
the
payload.
2.
See
port
adapter
module.
3.
See
pulse
amplitude
modulation.
panel switch A
commercially
successful
electrome-
chanical
telephone

switching
system
developed
in
the
AT&T
labs
in
1921,
based
on
Lorimer
one-step
se-
lection
concepts.
It
incorporated
mechanical
selectors
to
connect
calls.
At
the
time
the
panel
switch
was

introduced,
inde-
pendents
were
widely
using
the
step-by-step
switch
developed
a year
earlier.
The
panel
switch
technol-
ogy
allowed
customers
to
dial
their
own
calls,
albeit
with
a
lot
of
noise

in
the
early
versions.
The
panel
switch
was
widely
used
in
the
United
States
until
the
1950s,
when
it
was
superseded
by
the
crossbar
switch,
which
had
been developed
in
the

late
1930s.
See
crossbar
switch,
Lorimer
switch,
rotary
switch,
step-
by-step
switch.
panoramic receiverA
device
used
in
radio
commu-
nications
which
provides
continuous
monitoring
of
a
specified
band
of
frequencies.
On

acomputermoni-
tor,
signals
are
displayed
in
graph
form,
with
vertical
blips
moving
horizontally
along
the
X
axis
and
am-
plitude
graphed
on
the
Y
axis.
PAP
1.
packet-level
procedure.
2.

See
Public
Access
Profile.
paper
tape
An
infonnation
storage
medium.
Paper
designed
to
have
specific
areas
of
the
tape
encoded
and
punched or electrostatically recorded
onto
the
tape,
for
subsequent
reading
by
a paper

tape
reader
or
other
interpretive
device,
such
as
a
computer,
stock
ticker machine, player piano, or music
box.
This
means
of
information
encoding
and
storage
was
used
to
program
early
computers
and
had
many
character-

istics
in
common
with
computer punch
cards.
Early
telegraph receivers used paper
tape
systems
designed
by
inventors
such
as
Bain
and
Morse.
Later
teletypewriter
systems
used
tapes
to
save
transmis-
sion
time
and
money

by
being
composed
offline
and
sent
only
when
complete.
This
also
provided
a
way
to
correct
significant
errors
before
transmission,
since
a
bad
tape
could
always
be
repunched.
Paper
tapes

have
been
superseded
by
tape drives,
hard
drives,
floppy
diskettes, magneto-optical
discs,
cartridges,
and
memory cards.
See
Bain, Alexander; Morse,
Samuel
F.
B.
paper
tape
punch
A
device
designed
to
receive
or
interpret
coded
information

and
translate
it
into
physi-
cal
locations
on
a
paper
tape
and
punch
them
accord-
ingly.
paper
tape
reader
A
device
which
detects
and
trans-
lates
the
encoded
holes
in

punched paper
tape
as
the
tape
moves
through
the
machine.
The
machine
may
be
an
interface
to
a
display
device,
or
may
be
self-
contained.
Older paper
tape
readers
required
that
the

holes
be
completely
punched
out
and
were
usually
read
by
optical
means.
Later
machines
could
read
semi-perforated
or
chadless
tape,
usually
by
means
of
physical
sensors.
See
Hollerith
code,
paper

tape
punch,
punch
card.
PAR
1.
Positive
Acknowledgment
Retransmit.
2.
Pre-
cision
Approach
Radar.
parabolaA
plane
curve
that
is
frequently
studied
and
described
in
various disciplines including
physics,
geometry,
and
art.
Parabolic

curves
are
observed
in
721
© 2003 by CRC Press LLC