Fiber Optics Illustrated Dictionary - Part 10 pot

Fiber
Optics
Illustrated
Dictionary
Audion
Basic
Electronic Concepts
February
1998.AICE
studies
the
social
consequences
of
information
technology,
with
its
theoretical
and
practical
ramifications.
Australian Resource Information
and
Environ-
mentSatellite
ARIES.
A
low
Earth
orbit

(LEO)
sun-
synchronous satellite project for deploying a
hyperspectral
sensor
capable
of
identifying
details
of
the
Earth's surface
that
cannot
be
sensed
by
other
types
of
instruments.
Thus,
resource,
agricultural,
and
enviornmental
products
using
reflected
visible

and
infrared light gathered through about
96
spectral
bands
can
be
provided
to
commercial
markets.
The
CSIRO
Division
of
Exploration
and
Mining
has
been
coordinating
the
collaborative project. After
years
of
planning
and
feasibility
studies,
ARIES

re-
ceived
the
go-ahead
in
1995,
and
a
time
line
was
es-
tablished
for
it
to
become
operational
in
2001
(since
delayed
to
2002).
A
vertical
tracking
spatial
resolu-
tion

of
30
x
30
meters
is
possible
on
the
system,
which
can
be
increased
by
viewing
sideways
or
im-
proved
when
resolving
certain
high-contrast
objects.
/>Australian Speech Science
and
Technology Asso-
ciation Incorporated
ASSTA.

A
nonprofit
scientific
association
seeking
to
advance
research
and
under-
standing of speech science
and
its
application
in
speech
technologies
for
the
benefit
of
Australia.
authenticate
To
establish
the
identity
and
authori-
zation

status
ofa
user,
device,
process,
or
data
seek-
ing
entry
to
a
system
or
seeking
to
negotiate
a
trans-
action. Authentication
is
used
at
network access
points,
such
as
gateways
and
firewalls,

in
electronic
transactions,
such
as
purchases
or
contracts,
and
at
password
prompts
to
systems,
servers,
and
applica-
tions.
Data
is
often
authenticated
to
see
whether
it
has
been
altered
during

transmission,
and
email
messages
may
be
authenticated
before
being
sent
or
received.
See
certificate,
Challenge-Handshake
Authentication
Protocol,
Clipper
Chip,
encryption,
Pretty
Good
Pri-
vacy.
authentication,
authorization,
and
accounting
AAA.
A

network
security
approach
for
restricting,
controlling,
and
recording
remote
access
to
network
resources
on
an
individual
user
and
resource
basis
while
maintaining
an
audit
trail
for
system
adminis-
tration
and

billing.
authentication, basic access A
basic
authentication
scheme
for
users
accessing
Internet
services
speci-
fied
in
the
original
HTTP
protocol.
This
system
is
only
minimally
secure,
as
the
usemame
and
password
are
transmitted

as
text that
can
potentially
be
captured
and
read.
See
authenticate;
authentication,
digest
ac-
cess;
RFC
2617.
authentication, digest access A
means
to
provide
improved
security
for
HTTP
user
authentication
over
basic access authentication. See authenticate,
RFC
2069.

authenticator
In
packet
networking,
the
end
of
the
link
that
requires authentication,
and
specifies
the
authentication
protocol
to
be
used
in
the
link
estab-
lishment
phase.
See
Challenge-Handshake
Authen-
tication
Protocol.

I
III~

.~.
"#19~'
•
,

tllII.t~
FI&
I-alN.HECTIONB
amMa
TWO
WALUU
or .u.a
C'L-~T

1:}
"

i
it
.rnA
&-coNJlKCTIUNI
TO
OIt.':lUO-
QU.R
promotes self-regulation within
the
industry.

The
ACA
was
established
under
the
Australian
Commu-
nications
Authority
Act
1997
and
is
empowered
un-
der
the
Telecommunications
Act
1997
and
the
Radio-
communications
Act
1992.
It
falls
within

the
Com-
munications,
Information
Technology
and
the
Arts
portfolio.
/>Lee
de
Forest invented
the
Audion
through
trial and
error and
didn
tfully understand
why
it worked;
thus,
it
was
difficult
to
commercially manufacture consis-
tently reliable
tubes.
Edwin

H.
Armstrongsexplana-
tion
of
the
workings
of
the
Audion, published
in
Elec-
trical
World
in
1914, provided the theoretical back-
groundneeded
to
improve
manufacturingconsistency
and hencepractical applications
of
this important
in-
vention.
See
Audion.
rm.
! (X)NNICTIOHI
nl
OIl8BRV-

IJiG

0
CU'IR.ItNT
AHD
Gam
rorranIAL
Australian Computer Society
see
computer
societ-
ies,
national.
Australian Institute
of
Computer Ethics
AlCE.
A
national
organization
to
provide
research
and
education
to
the
public
and
advice

and
expertise
to
leadership
bodies
in
computer
ethics
in
Australia,
established
in
82
© 2003 by CRC Press LLC
authoring
The
process
of
using
authoring
systems
to
create
computer
software
or
multimedia
presenta-
tions
without

a
large
expenditure
in
time
in
learning
to
program.
The
rationale
for
authoring
is
to
free
the
creator
from
technicalities
to
concentrate
on
content
and
flow.
Authoring
involves
developing
a

scenario,
providing
content,
and
putting
them
together
in
an
interactive
environment
according
to
how
the
author
wishes
the
user
to
interact
with
the
software
or
pre-
sentation.
Some
authoring
languages

are
very
simi-
lar
to
English
or
BASIC.
Others
use
graphical
inter-
faces
to
allow
the
user
to
create
the
scenarios,
and
interrelate
the
program
building
blocks
with
a
mini-

mum
of
programming
or
text
entry.
authoringsystem, authoringlanguageA
high-level
computer programming language designed
to
be
quickly
and
easily
learned
and
used
such
that
profes-
sionals
(e.g.,
teachers)
with
expertise
in
their
specific
subject
fields,

but
without
programming
experience,
can
develop
computer
software
such
as
courseware
and
multimedia
presentations.
authorization Pennission
to
use
a
product
or
service
or
to
gain
entry
to
an
area
or
structure.

More
and
more,
computerized
means
are
being
used
to
assign,
track,
and
administrate
access
to
secure
areas
or
within
cor-
porate premises. Authorization
can
be
monitored
through
video
systems,
magnetic
cards,
retina

or
fin-
gerprint
scanning,
visual
recognition
of
faces,
pass-
words,
and
voice
recognition.
authorization code A
code
that
must
be
entered
into
a
telecommunications
system
to
gain
access
to
the
service
or

specific
features
of
the
service,
or
to
gen-
erate
statistical
records
of
use.
It
is
used
for
security
or
efficiency monitoring, frequently
on
touchtone
phone
systems
to
pennit
long-distance
calls
or
gather

departmental
data.
When
used
for
security,
the
code
is
often
typed
before
the
desired
number,
although
in
cases
of
departmental billing
or
monitoring,
it
might
be
required
after
the
number
has

been
dialed.
Authorization Code Table
ACT.
A
lookup
table
for
detennining
whether
a
phone
call
is
authorized
on
the
list
and
should
be
permitted
to
ring
through.
Ifa
num-
ber
is
not

found
on
the
list,
it
is
called
an
unmatched
call
and
may
be
rejected
or
fOlWarded
to
someone
in
authority.
authorized agent A
person
authorized
to
resell,
re-
lease,
or
represent
the

product
or
services
ofa
com-
pany
in
a
somewhat
cooperative,
independent
man-
ner
with
state
restrictions.
It
is
common
for
large
tele-
phone
carriers,
both
landline
and
wireless,
to
pennit

authorized
agents
to
resell
or
repackage
phone
ser-
vices
such
as
long-distance
services.
In
some
cases,
the
agent
is
a
software
developer
or
Internet
Services
Provider
(ISP)
who
works
with

the
phone
company
to
provide
digital
value-added
services.
authorized userA
person
or
entity
authorized
by
the
company
or
provider
to
use
a
service,
system,
or
spe-
cific
application
or
data
file.

This
concept
is
impor-
tant
in
communications
security.
auto answer
The
capability
ofa
telecommunications
receiving
device
to
automatically
detect
and
respond
to
an
incoming
transmission. Facsimile
machines,
BBS
modems,
and
answering
machines

are
examples
of
devices
with
auto
answer
capabilities.
Modems
typically
include
the
AutoAnswer
command
as
part
of
their
command
set.
Sophisticated
telephone
sys-
tems
can
be
configured
to
automatically
answer

a
voice
call
and,
by
using
Caller ill,
to
display
the
person's
file
on
a
computer
monitor.
See
Caller
ID,
Caller
Name,
bulletin
board
system,
auto
dial.
auto attendant, automated attendantAn
automated
voice
system,

designed
to
provide
a
24-hour
a
day
substitute
for
an
operator
or
receptionist,
that
answers
incoming
calls
and
plays
a
recorded
message
to
the
caller providing a
number
of
touchtone
options
or

selections
from
a touchtone-activated
menu.
Differ-
ent
systems
can
transfer
calls
to
humans
or
voice-mail
systems,
perform
transactions,
provide
information,
initiate
a
faxback
transmission,
or
initiate
a
fax
tone
for
those

with
manual
fax
machines.
The
better
sys-
tems
allow
you
to
go
to
submenus
without
waiting
for
the
current
recording
to
end
and
will
give
you
an
easy
way
to

return
to
the
main
menu.
Auto
attendants
are
used
by
banks,
mail
order
companies,
informa-
tion
service
companies,
and
others.
See
voice
mail,
Automatic
Call
Distribution.
Auto Busy RedialA
surcharge
phone
service,

multi-
line
subscriber
feature,
or
consumer
phone
feature
in
which
the
last
number
called
can
be
redialed
continu-
ously
until
a
connection
is
made.
The
system
recog-
nizes
a
busy

signal,
hangs
up,
and
redials.
There
is
a
similar
feature
in
most
telecommunications
software
that
is
used
to
connect
to
BBS
or
Internet
services
which
can
cycle
through
a
list

of
numbers,
trying
each
one
in
tum,
or
which
continuously
attempts
to
con-
nect
with
a
specific
number.
The
software
can
often
further
be
configured
to
dial
at
specific
intervals

or
for
a
specific
duration
of
time.
The
Auto
Busy
Re-
dial
service
is
useful
when
combined
with
auto
dial
for
voice
communications.
See
auto
dial.
auto dial, speed dial A
phone
feature
in

which
a
short
code
has
been
assigned
to
a
longer
number
to
allow
the
number
to
be
dialed automatically
with
fewer
keystrokes.
See
abbreviated
dialing.
auto dial capability A
softwarelhardware
applica-
tions
feature
for

dialing
a
phone
number
through
a
modem
and
setting
it
up
for
voice
rather
than
data
communication.
It's
very
handy
for
dialing
from
a
laptop,
acellular
laptop
link,
or
from

a
database
on
a
desktop
computer.
Some
phone
solicitors
use
auto
dial
in
conjunction
with
phone
listings
to
maximize
the
number
of
call
connects.
Be
aware
that
there
are
strict

regulations
governing
the
use
of
automated
pro-
cedures
for
phone
solicitations.
See
auto
answer.
auto discovery, auto mountAn
automated
process
whereby
a
network
server
is
alerted
to
a
new
device
on
the
system

and
can
gain
sufficient
information
about
its
operating
characteristics
to
bring
it
online
and
make
it
available
to
users.
Device
tables
and
da-
tabases
are
sometimes
used
to
make
this

possible,
and
manufacturers
are
creating
more
devices
that
signal
their
presence
and
include
electronically accessible
information about
the
brand, model,
capacity,
and
attributes.
83
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
auto start
1.
The
capability of

an
emergency
power
system
to
detect when electricity falls below a
cer-
tain crucial
level
and
start
up
standby
generators
to
provide
continuous
service.
2.
The
capability of a
computer
system
to
restart
or
reboot
after a power
outage
or

power
fluctuation
sufficient
to
take
down
the
system.
auto-negotiation
In
communications
between
two
or
more
entities,
the
process
of
setting
up
parameters
for
intercommunication
that
are
acceptable
to
both
par-

ties.
Auto-negotiation
commonly
involves selecting
the
communications
rate,
though
many
other
aspects
may
be
auto-negotiated. For example,
in
the
early
days
of
modem
communications,
a user
had
to
find
out
the
communications parameters
for
the

other
party
and
match
them
on
his
or
her
system
before
at-
tempting
to
make
a
connection.
By
the
early
1980s,
"autobaud"
modems
were
being installed
by
bulle-
tin board
service
(BBS)

providers
to
automatically
negotiate
an
acceptable
connection
speed
(you
still
had
to
set
some
of
the
other parameters
such
as
par-
ity,
stop
bits,
etc.),
thus
simplifying
the
process
for
busy

or
less
technical
users.
In
traditional
telephone
modems,
auto-negotiating a
speed
usually
involves
the
autobaud
modem
(e.g.,
at
the
ISP)
sending
out
a
series
of
modem
signal
tones
from
the
highest

to
the
lowest
available
speeds
until
the
user
modem
responds.
By
going
from
high
to
low,
the
fastest possible negotiation
is
chosen.
In
other
words,
if
the
ISP
can
provide
connections
at

speeds
up
to
9600
bps
and
the
user
dials
into
the
service
at
2400
bps,
the
ISP's
modem
would
start
sending
a
tone
signal
for
9600
bps,
if
there
is

no
response,
the
next
tone
might
be
5600
bps,
then
3300
bps,
until
it
reaches
2400
bps
at
which
point
the
user's
modem
should
respond
and
the
connection
is
negotiated.

Sometimes
the
autobaud
modem
will
go
through
the
sequence
a
couple
of
times
before
abandoning
the
call,
in
case
there
was
interference
on
the line that altered the
signal.
Auto-negotiation
is
now
an
integral aspect of

many
communications
networks.
For
example,
ports
on
an
Ethemetwork
auto-negotiate
during
the
linking
phase
ofa
connection
(the
same
general
idea
as
two
mo-
dems
negotiating
a transmission
speed
for
connect-
ing

over
phone
lines).
The
capability
is
now
com-
monly
built
into
hubs
and
network interface
cards
(NICs)
as
part
of
the
1
OOBASE-
TX
and
other
stan-
dards
(it
is
optional

in
the
100BASE-SX
standard).
Auto-negotiation
pulses
are
transmitted
in
pairs,
with
a
clock
pulse
and
a
data
pulse
and
repeated
at
inter-
vals.
Since
fiber
standards
did
not
originally
include

auto-negotation
in
the
sense of
the
1
OOBASE-
TX
standard,
an
emulation
system
for
a link pulse
was
devised
for
fiber-based
transmissions,
with
adjust-
ments
for
the
different
timing
needs
of
fiber
loss

ver-
sus
twisted
pair.
See
handshake.
autoanswer
See
auto
answer.
autobaud
The
capability
of
a
modem
to
detect
the
incoming
baud
rate
and
adjust
its
transmission
speed
and
handshaking
to

match
the
rate
in
order
to
estab-
lish
a
connection.
Useful
in
24-hour
a
day,
unattended
84
services
like
BBSs
and
on
systems
that
may
be
serv-
ing
a variety of
types

ofcomputers
and
modems.
autobaud rate
Early
modems
had
to
be
individually
matched
to
the
same
baud
rate
in
order
to
communi-
cate
successfully
with
one
another,
but
since
the
mid-
1980s,

when
1200
baud
transmissions
were
common,
most
modems
have
incorporated autobaud capabili-
ties
in
which
the
called
modem
and
the
calling
mo-
dem
negotiate a
common
speed
and
then
commence
with user communications. Autobaud capabilities
have
been a great boon

to
bulletin board systems
(BBSs)
and
Internet
Service
Providers
(ISPs)
as
they
must
accommodate
users
calling
in
on
a variety of
types
ofcomputers
and
modems.
autodialing recorded message player
ARMP.
An
automatic
dialer
which
plays a recording
to
the

per-
son
who
answers
the
phone
to
keep
him
or
her
on
the
line
until
an
agent
can
take
the
call.
ADRMP
systems
are
disliked
by
many
callees
who
consider it

intru-
sive
to
pick
up
the
phone
and
be
connected
to
a
re-
corded
message
and
asked
to
wait.
Nonetheless,
they
are
used
by
telephone solicitors
and
collection
agen-
cies
to

increase dialing
and
caller connect
efficiency.
AUTODIN Automatic Digital
Network.
A global
communications network of
the
U.S.
Department of
Defense.
Autoplex
The
first
commercially significant
semi-
automatic
telegraph
key,
jointly
developed
by
Horace
G.
Martin
and
Walter
Polk
Phillips

(developer
of
the
Phillips telegraph code).
The
device
was
patented
in
1902
by
Martin.
See
73,
Phillips
code.
Automated Attendant
See
Auto
Attendant.
Automated Attendant Billing System
AABS.
In
telephony,
a system
in
which
the
caller
dials

collect
and
long-distance
calls
with
the
aid
of
an
automated
voice
prompting
system
that
seeks
authorization
from
the
called
party,
connects
or
rejects
the
call,
and
bills
accordingly. Most telephone services
in
North

America
have
become
automated
in
this
way
with
the
use
of
speech
recognition
and
synthesized operator-
assist
voices.
automated
voice
response systemA
VRS.
A
system
designed
to
respond
to
voice
commands
without

the
intervention ofa
human
operator.
This
type
of
sys-
tem
is
often
used
over
telephones
by
banks
and
mail
order
companies.
It
is
sometimes
used
for
security
purposes
and
building
access.

It
is
applicable
to
visi-
tor information
systems
installed
in
kiosks
in
amuse-
ment
parks
and
other tourist attractions.
See
speech
recognition, voice
recognition.
Automated DirectoryAssistance CanCompletion
ADACC.
Atelephone directory
call
completion
ser-
vice
made
commercially available
to

telephone
ser-
vice
carriers which automatically directs a
call
with
information provided
by
the
caller.
In
some
areas
it
has
superseded
the
familar
Directory
Assistance
(DA)
service.
The
service
is
usually billed
to
subscribers
on
an

as-used
basis.
See
Automated
Directory
Assis-
tance
Service.
Automated DirectoryAssistance Service
ADAS.
A
commercial
telephone
service
in
which
a
speech
rec-
ognition system
is
used
to
get information
from
a
© 2003 by CRC Press LLC
caller
who
has

requested
directory
assistance.
It
re-
quests
the
location
and
name
and
then
either
provides
the
phone number or compresses out pauses
and
patches
the
call
to
an
operator
who
provides
the
phone
number.
Ifacaller
is

tentative
or
repetitious,
the
au-
tomated
service
can
reprompt
and
then
pass
on
only
relevant
information
for
the
operator.
Automated Interchange
of
Technical Information
MIL-STD-1840x.
A
data
interchange
standard.
automated loop test
ALT.
An

automated
system
for
testing
traditional
telephone
service
lines.
Cables
can
be
scanned
for
excessive noise, aberrations, water
faults,
or
outright
failure
and
traffic
routed
through
a
backup
loop
until
the
fault
is
corrected.

Loop
tests
may
be
run
on
aregular
basis
(e.g.,
once
a
day),
usu-
ally
during
low
traffic
times.
Automated Maritime/Marine Telecommunica-
tions System
AMTS.
The
AMTS
is
a specialized
network
of
public
coast
stations

providing
commu-
nications
over
inland
waterways
and
ocean
coastlines.
Public
coast
stations
(marine operators)
are
desig-
nated
as
common
telephone
carriers;
they
provide
a
means
to
connect
marine
radio
transmissions
to

the
public
switched
telephone
network
(PSTN).
In
Spring
2000,
Mobex
Communications
Inc.
ac-
quired Regionet Wireless,
which
had
licenses
for
more
than
3900
channels
in
the
AMTS
system
serv-
ing
the
west

and
east
coasts.
This
announcement
came
soon
after
the
Mobex
announcement
of
intent
to
ac-
quire
Waterway
Communications System
LLC,
a
holder
of
licenses
for
over
4000
channels
serving
the
Gulf Coast

and
Ohio
River barge industry.
Thus,
Mobex
became
a significant provider of
marine
mo-
bile
radio
services
in
North
America.
AutomatedMessage Handling System AMHS. An
interface
between
an
automatic
digital
network
and
a
local
area
network
intended
to
facilitate

the
delivery
of
messages
to
a user's
desktop
station.
AMHS
was
developed
by
NASAlJPL
with
funding
from
the
u.S.
Department
of
Defense
and
subsequently
transferred
to
the
Telos
Corporation
for
servicing

requests.
Automated
Packet
Recognition/Translation
APaRT.
A
Cisco
Systems
technology
that
allows
au-
tomatic.
network
configuration
and
translation,
e.g.,
Ethernet
clients
and
a
CDDI
or
FDDI
server,
so
that
workstations
or

switches
do
not
have
to
be
individu-
ally
configured.
APaRT
recognizes
and,
if
necessary,
translates specific data link layer encapsulation
packet
types.
automatic alternate routing
AAR.
1.
A
telephony
service
for
placing
calls
that
will
be
automatically

routed
through
the
most
economical
path
available
at
the
time.
It
is
spelled
with
capitals
when
referring
to
a
subscriber
service
specifically
offered
by
a
phone
company.
2.
A
network

service
for
obtaining a
con-
nection
through
an
alternate
route,
if
the
primary
route
is
unavailable,
without
user
intervention.
Automatic Call Distribution
ACD.
A multiline
phone
capability
or
service
that
automatically
man-
ages
and

routes
incoming
calls
to
assigned
lines.
If
there
are
no
available
lines
at
the
moment
the
call
is
received,
it
is
placed
on
hold,
and
may
be
configured
to
playarecording

such
as
"Your
call
is
important
to
us,
please
stay
on
the
line
and
your
call
will
be
an-
swered
in
the
order received."
ACD
systems
can
put
the
party
on

hold
and
playa
recording,
or
they
can
be
quite
sophisticated, performing significant
traffic
direction
and
business
transactions.
Mail-order
companies,
airlines,
and
other
high
phone-
traffic businesses utilize
ACD
systems, although
smaller
companies
are
starting
to

use
them
as
they
become
less
expensive.
An
ACD
system
detects
and
answers
incoming
calls,
searches
a
database
for
in-
structions
on
how
to
handle
the
call,
responds
to
the

call
(as
with
a
recording),
and
reroutes
it
appropri-
ately
as
human
operators
become
available.
The
rout-
ing
itself
can
be
programmed
to
the subscriber's
needs,
with
a
number
of
options

available:
Uniform
distributes
calls
evenly,
Top-down
distributes
the
calls
according
to
a
list
in
the
same
order
each
time,
so
that
calls
go
to
the
top
of
the
list
first,

and
work
their
way
down,
and
Specialty
distributes
calls
acco~ding
to
the
callee
who
most
appropriately
can
handle
the
call.
ACDs
can
also
be
used
to
gather statistical
data
on
the number

of
calls received, and
how
they are
handled
in
order
to
fine-tune
the
system,
and
to
re-
spond
to
the
business
needs
of
the
subscriber
to
im-
prove
call
handling
or
change
it

as
the
need
arises.
See
Centrex,
private
branch
exchange.
automatic call gapping
ACG.
A
scheme
to
help
con-
trol
system
congestion
at
the
call
establishment
stage
in
wireless intelligent
networks
(WINs).
ACG
intro-

duces
a
minimum
time
gap
between
call
attempts
and
permits
a
maximum
number
of
attempts
per
defined
unit
of
time
if
call
volume
is
high.
Implementations
vary,
but
gaps
of

about
a
second
are
common.
In
the
late
1990s,
ACG
was
tested
for
performance
improve-
ments
in
a
number
of simulated
and
real
networks,
including
A-link
loads.
Prouskas
et
al.
have

more
recently
proposed
a
multi-
agent
system
for
controlling network
load
that
may
give
better performance results
for
load
control
of
network
components
than
ACG.
automatic callback A subscriber option usually
found
on
private
branches
in
which
a

caller
can
key
in
a
code
or
press
a
button
for
automatic
callback
if
she
or
he
has
encountered a
busy
signal
on
an
exten-
sion
line.
When
the
line
is

freed,
the
caller's
phone
and
the
callee's
phone
both
ring
so
that
the
connec-
tion
can
be
made.
automatic calling unit
ACU.
A
device
used
to
auto-
matically
dial
numbers
(a
modem

and
the
appropri-
ate
software
can
also
do
this)
in
order
to
save
a
hu-
man
operator
the
time
and
inconvenience of
dialing
a lot
of
calls. This type
of
system is used by
fundraisers, telemarketers, researchers,
and
others

who
make
frequent
calls
to
a predetermined list of
numbers.
On
computer systems,
ACU
software
is
sometimes
coupled
with
database
directory
programs
or
address
books.
Automatic
Circuit
Assurance
ACA.
Acircuit ef-
ficiency
feature
available
to

private
branch
exchange
(PBX)
telephone
subscribers.
ACA
evaluates
and
re-
ports
on
phone
trunk
usage
or
malfunctions.
Trunks
85
~.
.
:.~
••.
;.:
•.
:
.•.
;
•.•.
1

•
~
••
:~
.•.
:.
.
,~1
•
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
are
typically
evaluated
on
whether
they
are
in
use
or
locked,
and
whether
holding
times
are

long
or
short.
ACA
can
also
be
used
to
chart
unusual
patterns
to
facilitate
troubleshooting.
When
apotential
problem
is
detected,
an
attendant
is
notified.
Automatic
Data
Capture Association
ADCA.
An
Australian association

of
companies involved
in
manufacturing,
distribution,
and
consulting
for
the
data
capture
industry.
ADCA
promotes
the
develop-
ment
and
maintenance
of
standards
and
education
in
data
capture.
Some
specific
data
capture

areas
include
radio
communications,
vision
systems,
optical
char-
acter
recognition,
barcode
interpretation,
mobile
pen
computing,
scanning,
and
others.
/>automatic dialer, autodialer A
timesaving
device
enabling
a
user
to
program
and
store
a
short

sequence
of
characters
to
represent
a
long
number.
When
the
short
sequence
is
entered,
the
phone
checks
memory
and,
if
the
sequence
is
found,
it
automatically
dials
the
corresponding
long

number.
See
speed
dialing.
automatic direction finder
ADF.
An
antenna
that
usually
rotates
or
arcs
back
and
fOlWard
and
continu-
ously
monitors
signals
until
it
finds
a
strong
one
or
one
with specified desired characteristics. It

then
locks
onto
that
signal
or
provides
the
direction
or
fre-
quency
information
on
some
type
of
output
device
such
as
a
monitor
or
dial.
Automatic Electric Company Ahistoric
telephone
technology vendor supplying automatic switching
systems
based

on
Strowger
technology,
co-founded
in
1901
by
Almon
B.
Strowger,
a
mortician
who
re-
portedly
wanted
an
automatic
exchange
because
hu-
man
operators
were
diverting
business
to
his
com-
petition.

This
company
was
able
to
compete
by
in-
stalling
working
systems
quickly,
according
to
cus-
tomer
specifications,
and
was
the
largest
company
supported
by
telephone
company
independents. It
was
directed
by

Alexander
E.
Keith.
Originally
most
of
the
Automatic
Electric
systems
were
three-wire
systems
which
used
two
wires
plus
the
Earth
as
the
third
return-path conductor
for
the
transmission.
Later,
they
developed

a
two-wire
sys-
tem.1n
1955,
the
company
was
merged
into
General
Telephone
and
Electronics
(GTE).
See
Strowger
switch.
automatic exchange A
central
telephone
switching
office
in
which
calls
from
subscribers
are
automati-

cally
routed
to
the
callee
through
mechanical,
elec-
tromechanical,
or
electronic
switching.
There
are
still
a
few
operator-assisted
exchanges
around,
mostly
in
remote
locations
or
third-world
countries,
but
auto-
matic

exchanges
are
found
in
most
developed
nations.
The
history
of
automated
exchanges
is
interesting.
Besides
the
economic
motivation
of
not
having
to
pay
wages
to
operators,
one
of
the
early

switching
sys-
tems
was
designed
by
a
mortician
because
he
was
apparently
concerned
that
operators
were
channeling
calls
to
his
competition.
automatic exclusion
Once
a
call
has
been
answered,
subsequent
stations,

nodes,
or
consoles
are
excluded
from
having
access
to
the
line.
86
automaticfrequency control
AFC.
1.
Periodic
sam-
pling
ofa
frequency
modulated
(FM)
signal
to
focus
the
receiver
on
the
approximate

center
of
the
trans-
mission
band.
This
came
into
widespread
use
in
the
1930s.
2.
A
device
that
can
seek
aparticular
frequency
or
monitor
the
incoming
frequency
to
keep
the

tun-
ing
accurate.
AFC
is
common
on
FM
receivers
and
other
devices
that
must
maintain operations
within
a
very
narrow
range.
automatic gain control, automatic volume control
AVC.
Acircuit
designed
to
sense
the
level
of
incom-

ing
sounds
and
adjust
their
volume.
It
can
serve
two
common
purposes:
to
increase
the
dynamic
range
of
the
sound
by
making
quiet
sounds
quieter
and
loud
ones
louder;
or

to
condition
the
sound
by
making
the
volume
more
consistent (e.g.,
by
quieting
down
the
loudest
sounds
and
strengthening
the
quietest
sounds)
when
incoming
signals
are
fluctuating
more
than
is
desired.

Volume
conditioning
is
widely
incorporated
into
sound
receivers
with
tuners,
as
the
signal
com-
ing
through
an
antenna
can
vary
significantly
due
to
varying
broadcast characteristics
and
weather.
automatic hold A
convenience
in

which
the
opera-
tor
ofa multiline
telephone
console
or
switchboard
can
switch
between
active
call
lines
without
having
to
push
a
hold
button.
This
saves
operator
time
and
prevents caller frustration
as
the

operator can't
un-
intentionally disconnect
the
caller
by
forgetting
to
press
the
hold
button.
automatic identification technology
AlT.
A
general
category
of technological
tools
for
facilitating
and
automating
recognition of
goods,
processes,
or
indi-
viduals.
There

are
software
programs
for
automati-
cally
recognizing individuals
by
biometric
data
such
as
voice
prints, fingerprints,
facial
features,
retina
scans,
etc.
Bar
codes
and
radio
frequency
tags
are
used
for
recognition of
goods

in
shipping
and
inven-
tory
management
systems
in
many
distribution
and
retail businesses.
In
March
2001,
the
U.
S.
Defense
Logistics
Agency
published
the
Defense
Logistics
Agency
Automatic
Identification
Technology
Imple-

mentation
Plan
which
details
the
integration ofAlT
into
its
business
processes
for
collecting
source
data
and
asset
information.
Used
wisely,
AIT
has
the
potential
to
reduce
repeti-
tive
work
and
manual

label-reading
and
-processing.
It
can
also
be
practical
for
surveillance
and
security
applications, provided people's privacy rights
are
taken
into
consideration.
Automatic Identified
Outward
Dialing AlOD. A
multiline phone option that records
the
extension
number
of
the
originating
phone
in
order

to
facilitate
billing.
AlOD
is
especially
common
for
the
identifi-
cation
oflong-distance
calls.
AlOD
leads
are
termi-
nal
leads used
to
transmit this information
to
the
phone
carrier.
automatic level control
See
automatic
gain
control.

automatic light controlA
feature
on
many
different
types
of
cameras,
in
which
the
camera
will
adjust
the
settings
to
changes
in
lighting
without
manual
me-
tering
or
intervention
by
the
user.
This

feature
is
par-
ticularly prevalent
on
small
automatic
cameras
and
© 2003 by CRC Press LLC
many
camcorders. Sometimes backlighting, high
contrast,
and
other
lighting
situations
can
be
preset
with buttons
so
that a general ambience
is
made
known
to
the
camera,
but

the
final
settings
are
still
automated.
Professionals
prefer
automatic
systems
only
if
they
also
have
a
manual
over-ride
for
tricky
lighting
situations.
Automatic Line
Insulation
Testing
ALIT.
Test
equipment
used
by

telephone
companies
to
identify
and
test
faulty
outside
cables,
when
not
in
use,
by
seeking
below-threshold
leakage
resistance.
Results
can
be
communicated
by
various
means
to
an
atten-
dant
or

test
facility.
ALIT
testing
is
quick
and
is
typi-
cally
conducted
during
low
traffic
hours
in
order
not
to
tie
up
the
system.
automatic line hold
See
automatic
hold.
automatic link establishment
ALE.
In

radio
com-
munications
and
computer
networking,
the
capabil-
ity
ofa
system
to
negotiate
automatically
a
connec-
tion
between
two
or
more
stations. Handshaking,
identification,
and
authentication
may
be
part
of
the

process.
In
radio communications,
ALE
systems
sometimes
require
a
table
or
list of
frequencies
that
are
likely
to
result
in
a
successful
connection.
In
com-
puter
modem
links,
a
record
of
communication

pa-
rameters
and
modem
speeds
(if
not
autobaud)
may
be
maintained
to
facilitate
automatic
connections.
Au-
tomatic
link
establishment
is
now
common
and
al-
most
taken
for
granted,
but
until

the
mid-1990s,
in
computer
communications
especially,
automatic
con-
nection
was
in
no
way
guaranteed
and,
in
many
cases,
not
even
possible.
automatic location identification, automatic loca-
tion information
ALI.
A
feature
of
enhanced
911
emergency

systems
that
automatically
provides
in-
formation
on
the
source
of
the
call
from
a
database.
automatic loop protection switching
ALPS.
A
net-
work
flow
protection
mechanism
that
protects
data
flow
by
switching
to

a
redundant
or
other
backup
sys-
tem
to
continue
service
until
corrections
can
be
made
to
the
faulty
circuit.
In
a
loop
system,
the
backup
sys-
tem
provides
a
different

physical
path
for
the
data.
This
type
of
system
is
suitable
for
localized
computer
networks
as
opposed
to
public
distributed
networks.
In
telephony,
there
are
similar
systems
for
switching
to

a
backup
loop
if
the
main
loop
is
faulty.
Automatic Network Dialing
AND.
Also
called
Au-
tomatic
Dialing
(AD),
AND
is
a
means
of
using
ap-
plications
to
dial
a
telephone
number

on
a
digital
net-
work
or
from
various
electronic
peripheral
devices
on
a
network
(e.g.,
a facsimile
machine).
For
ex-
ample,
a
database
of
phone
numbers
can
be
accessed
by
a

computer-based
dialing
utility
to
dial
the
num-
bers
in
succession
until
a
call
is
answered,
to
dial
a
single
number
repeatedly,
or
to
dial
specific
numbers
on
a
programmed
schedule.

The
Telephony
Applica-
tion
Programming
Interface
(TAPI)
is
one
of
the
soft-
ware
programming
tools
that
facilitates
the
develop-
ment
of applications
to
communicate over
phone
lines,
using
computers
to
handle
the

routine
dialing
tasks.
AND
is
widely
used
by
businesses
that
seek
to
automate
their
customer
call-backs
or
telemarketing
calls.
With
Internet
phone
and
Voice
over
IP
becom-
ing
increasingly
prevalent,

AND
is
gaining
in
impor-
tance.
See
war
dialer.
~~:~%:~;~~;:;:se~h~~:.::a:~~:~
~~~tt:~.
provided
the
callee
has
the
service
and
equipment
to
display
the
information.
It
was
historically
distin-
guished
from
Caller

ill
by
the
number
of
rings
within
which
the
information
was
sent
to
the
caller,
but
that
distinction
is
disappearing.
See
Caller 10,
Signaling
System
7.
2.
A
multi
frequency
signaling

parameter
by
which
a
long-distance
carrier
receives
the
caller's
number
from
the
local
carrier
for
billing
purposes.
automatic privacyA
feature
on
some
multiline
sys-
tems
that
automatically
locks
out
the
ability

of
other
people
who
pick
up
a
phone
to
select
the
line
already
in
use.
These
systems
may
also
include
a 'release'
button
that
allows
others
to
pick
up
the
line

and
join
the
conversation.
Automatic Protection Switching
APS.
A
network
switching
technique
which
varies
from
system
to
sys-
tem.
In
some,
it
is
a
device
that
automatically
switches
from
a
primary
to

a
secondary
circuit
if
excessive
er-
ror
conditions
are
detected
on
the
primary
circuit.
For
Synchronous
Optical
Networks
(SONETs),
APS
is
defined
in
ANSI
Tl.105-1995.
In
SONET,APS
car-
ries
the

signaling
bytes
associated
with
establishing
and
releasing
the
protection
of
the
optical
facility.
Automatic Recall
AR.
A
subscriber
telephone
ser-
vice
that
allows
a
callee
to
dial
automatically
to
the
number

that
most
recently
tried
to
reach
the
callee.
It
allows
the
callees
to
reach
the
caller
that
they
missed
picking
up
or
that
they
missed
as
a
Call
Waiting
while

they
were
already
on
the
line.
If
the
automatically
dialed
line
is
busy,
the
automatic
dialing
can
continue
for
up
to
half
an
hour.
Ifa
connection
is
made,
a
ring

alerts
the
user
to
the
completed
connection.
automatic recovery If
there
is
a power
outage
or
other
problem
that
interrupts
a
phone
system,
bulle-
tin
board
system,
network,
etc.,
automatic
recovery
is
the

capability of
that
system
to
power
up
to
oper-
ating
status
and
to
recover
as
many
of
the
original
operating
parameters
and
files
as
possible,
as
well
as
to
recover
or

recreate
the
information
that
was
con-
tained
in
memory
that
is
of
importance
to
continued
operations.
Automatic Redial A
surcharge
phone
service
that
allows
a caller
to
recall
the
most
recent
previously
dialed

number
and
dial
it
again
by
inputting
a
short
code
instead of rekeying
the
whole
number.
It
is
handy
if
the
line
was
busy
the
first
time
it
was
called.
Many
business

and
consumer
phones
now
have
a
re-
dial
button,
thus
decreasing
demand
for
this
service.
automatic rerouting
The
capability ofa
system
to
route
a
transmission
through
another
leg,
hop,
or
path
when

the
original
or
expected
path
is
not
available.
Dynamic
routing
in
large
systems
often
works
this
way.
Large
distributed
systems
where
the
physical
and
virtual
pathways
change
constantly
usually
func-

tion
with
automatic
rerouting.
In
some
systems,
such
as
Fiber
Distributed
Data
Interface
(FOOl),
alternate
routing
is
supplied
in
a
dual
ring
system
in
which
the
87
© 2003 by CRC Press LLC
AUUG Australian
Unix

User
Group.
AUXBC
auxiliary
broadcasting.
signed
to
carry
out
many
of
the
transaction activities
(usually
financial)
that
have
historically
been
handled
by
human
bank
tellers.
Typical
ATM
functions
in-
clude
deposits,

withdrawals,
payments,
transfers,
and
balance
inquiries.
ATMs
are
intended
to
provide
ser-
vices
24
hours
a
day
or
an
option
to
those
who
prefer
automated
services.
ATMs
are
networked
to

a central system, if
free-
standing
or
off-site,
or
they
may
be
directly
linked
to
the
local
network
when
attached
to
the
building
with
which
it
is
associated.
automatic
volume
control
AVC.
Acircuit

in
a
radio
receiver designed
to
prevent
loud
blasts
from
strong
transmitting stations
when
the
user
moves
the
dial
through
the
various
stations.
It
can
be
disconcerting
to
tune
through
several
weak

stations
and
then
hit
a
strong
one
that assaults your
ear
drums.
AVe
was
designed
in
the
1930s
to
prevent
these
sudden
gains
and
dramatic
volume
changes,
and
most
systems
now
incorporate

this
feature.
automatic wakeup A
timing
device
that
creates
an
alarm
or
other alert
to
wake
up
a
person.
These
can
include
a
clock
radio,
alarm
clock,
bell,
computer
pro-
grammed
sound
file,

or
telephone
signal.
Automation
Tooling
Systems
ATS.
A
leading
inter-
national
provider of
automation
systems
integration.
ATS
designs
and
manufactures
factory
automation
systems,
custom
automation
equipment,
and
high-
volume precision components.
The
company

has
been
developing
custom
automation
solutions
for
fi-
ber
optics,
optoelectronics,
and
photonics
industries
since
1994.
autonomous built-in self test
ABIST.
The
capabil-
ity
ofa
system
to
automatically
run
built-in
diagnos-
tic
routines.

autonomous switching A
Cisco
Systems
router
fea-
ture
that
enables
the
ciscoBus
to
switch
packets
in-
dependently,
without interrupting
the
system
proces-
sor,
to
provide
faster
packet
processing.
Autonomous System Number
ASN.
A common
administrative
routing

setup
identifier,
that
is,
rout-
ing
through
acollective
numbered
common
domain.
The
ASN
designates a
system
under
common
opera-
tions
control,
using
common
routing
protocols,
with
the
various
routing
tables
dynamically

maintained.
AVV,
AVV
bit
ATM
User-to-User
bit.
A payload
type
identifier
(PTI)
field
bit
used
with
AAL5
to
in-
dicate
the
end
ofa higher
protocol
packet
(e.g.,
the
IF
packet).
The
PTI

is
defined
for
all
AAL
types
with
regard
to
AUU
as
shown
in
the
chart.
signal condition AUU bit
Fiber
Optics
Illustrated
Dictionary
port
adaptor
and
various
ports
are
quickly
reconfig-
ured
to

the
secondary
systems
to
prevent
loss
of
data
and
connectivity.
automatic retransmit request, automatic repeat
request
ARQ.
In
its
simplest
form,
as
in
CB
radio,
a
verbal
request
for
the
sender
to
repeat
a

message
that
did
not
come
through
clearly
or
completely.
More
standardized,
automated
ARQ
systems
exist,
including
one
in
which
characters
are
sent
in
groups
ofa
set
length,
and
the
sender

waits
for
an
acknowl-
edged
(ACK)
or
not
acknowledged
(NAK)
signal
(or
no
response)
before
retransmitting
or
continuing.
In
some
systems,
such
as
amateur
radio
communica-
tions,
ARQ
is
called

mode
A.
In
high-speed
data
transmission,
error-detection
fields
are
built
into
the
data
and
used
as
check
fields
by
the
recipient.
As
in
broadcast
ARQ
systems,
an
acknowl-
edge
(ACK)

or
not
acknowledge
(NAK)
is
transmit-
ted
to
the
sender
and
the
sender
responds
accordingly.
Automatic Route Selection A
phone
service that
automatically
seeks
and
selects
the
desired circuit
from
available
options
(usually
the
least

expensive
carrier)
for
the
path
of
an
outgoing
call.
See
Least
Cost
Routing.
Automatic
Scheduled
Testing
AST.
A
form
of
tele-
phone
testing
in
which
the
telephone
carrier
provides
test

lines
with
associated
responders
for
conducting
loss
and
noise
tests
on
a
scheduled
basis.
Additional
testing
may
be
requested
at
an
extra
charge
from
the
central
provider.
Test
results
are

logged
for
each
trunk
line
and
provided
to
the
carrier.
Automatic Sequence Controlled Calculator
(ASCC).
See
Harvard
Mark
I.
automatic sounder A
historic
telegraph
device
that
created
audible
clicks
of
the
incoming
transmission
that
could

be
heard
and
interpreted
by
the
telegraph
receiving
operator.
The
term
was
also
applied
to
a
sounding
device
used
for
the
teaching
of
telegraphic
sending
and
receiving
skills.
When
contact

was
made
between
the
arm
and
the
stop,
the
sounder's circuit
was
closed.
See
sounder.
Automatic
Speech
Recognition
ASR.
A
term
in
te-
lephony
services
for
the
capability
to
interpret
auser's

verbal
response
to
prompts
in
order
to
facilitate
call
direction
or
other
handling.
automatic
switching
system
Various
types
of
me-
chanical
and
electrical
telephone
switching
systems
became
prevalent
after
the

invention
of
the
historic
Strowger
telephone
switching
system.
These
auto-
matic
systems
enabled
telephone
circuitry
to
be
con-
trolled
so
that
a
call
was
connected
by
dialing
a
code
rather

than
by
asking
a
human
operator
to
manually
patch
through
the
call.
A
number
of
large
and
small
telephone
switching
manufacturers,
including
AT&T
/
Bell
and
the
Lorimer brothers, created automatic
switching
equipment

in
the
early
1900s,
a
trend
that
continued
until
the
1970s.
By
the
1980s,
very
few
manual
systems
were
in
use
except
in
rural
or
spe-
cialized
situations,
as
they

had
been
superseded
by
electronic
switching
systems.
Automated
TeUerlTransaction
Machine
ATM.
Any
automated
walk-up
or
drive-up
console
system
de-
88
no
congestion
no
congestion
congestion
congestion
AUUO
AUUl
AUUO
AUU 1

bit pattern
000
001
010
011
© 2003 by CRC Press LLC
availability
1.
The
amount
of
time
during
which
a
telephone
or
network
system
is
available
for
handling
calls.
It
is
expressed
as
the
ratio of

denied
calls
to
at-
tempted
calls.
See
reliability.
2.
In
Global
Position-
ing
Service
(GPS),
the
period of
time
during
which
a
particuhtt
location,
within angle
of
elevation
param-
eters,
has
sufficient

satellites
to
make
a position
fix.
Available BitRate
ABR.
InATM
networking,
a
layer
service category related
to
flow control that
may
change
subsequent
to
establishing
the
connection.
ABR
is
related
to
Best Effort
service.
It
is
a class of

service
(CoS)
defined
by
the
ATM
Forum
that uti-
lizes
bandwidth
on
an
availability basis
for
the
trans-
port
of
bursty
data
traffic.
It
is
designed
to
approxi-
mate
the
traffic
characteristics ofexisting

local
area
network
(LAN)
protocols.
In
network
implementa-
tions,
there
is
generally
an
Available
Bit
Rate
(ABR)
command
that
facilitates
the
configuration ofpeak
and
minimum
cell
rates
in
kilobits per
second.
See

cell
rate,
constant
bit
rate,
variable bit
rate.
available bit rate
ABR.
avalanche diode A
diode
in
which
there
is
a
break-
down
region
in
the
reverse
bias
that
is
triggered
at
a
certain
voltage.

This
makes
them
useful
as
voltage
regulating
components.
See
diode;
zener
diode;
pho-
todiode,
avalanche.
avalanche noise In semiconductor junctions, a situ-
ation
in
which
sufficient high-voltage energy
is
gen-
erated
by
some
carriers
such
that
others
are

physi-
cally
impacted.
avatar
1.
An
embodiment
in
human
form.
2.
An
elec-
tronic
image
or
other embodiment of
an
individual
that
is
computer-generated
and
holds
some
essence
or
presence
ofindividuality
or

actuality beyond
that
of a photographic image or
scan.
This concept
is
prevalent
in
the
imaginary
world
ofcomputer
gam-
ing
(and
Internet
chat
areas), especially
in
virtual
re-
ality
simulations.
AVD
See
alternate
voice
data.
average busy hour
The

hour
in
a
day
during
which
the
most
traffic
is
carried
on
a
system.
This
informa-
tion
is
important
for
configuring
and
tuning
computer
and
telephone
networks
to
handle traffic
efficiently.

Average Delay in Queue
ADQ.
A measure of
the
average
time
a caller waits before a telephone
call
is
processed
or
handled
by
an
agent.
It
is
important
to
keep
this
time
as
short
as
possible,
to
discourage
the
caller

from
hanging
up
or
negatively perceiving
the
service.
average line utilization
ALD.
A telephony
admin-
istrative
statistic
describing
average
bandwidth
usage
over
a specified period
of
time.
The
information
is
useful
in
managing bandwidth
in
a multichannel
system.

average speed ofanswer
ASA.
Atelephony
admin-
istrative statistic describing
the
average
time
it
takes
for
an
operator
or
automated
system
to
answer a
call,
usually
measured
in
seconds.
ASA
is
used
for
sys-
tem
configuration, statistical,

and
staff training
and
management
purposes.
AVHRR
See
advanced very high resolution radi-
ometer.
aviation channelsA
set
ofbroadcast
frequencies
set
aside
for
aviation communications
and
aviation-re-
lated
signaling/sensing purposes
(e.g.,
radar).
AVIOS
See
American
Voice
Input/Output
Society.
AVRS

See
automated voice response
system.
AVSSeS
See
AudioNisual
Service
Specific
Conver-
gence
Sublayer.
AWA
See
Antique
Wireless
Association.
AWACS
SeeATMWirelessAccess
Communication
System.
Awe
See
Association
for
Women
in
Computing.
AWG
1.
See

American
Wire
Gauge.
2.
Association
for
Women
Geoscientists.
3.
Association
of
Washing-
ton
Geographers.
awk
An
interpreted computer
language
common
on
Unix
systems,
developed by
Aho,
Weinberger,
and
Kernighan
(who
is
also

an
author of
C).
It
has
a
C-like
syntax.
See
Perl.
AX.25 A communications protocol designed for
packet
radio
communications
that
operates
at
the
link
layer
level.
It
is
based
on
the
ISO
Open
Systems
In-

terconnection Reference
Model
(OSI-RM).
Since
its
introduction,
it
has
generally been superseded
by
NETIROM,
a
more
flexible
means
of
transmission.
See
Open
Systems
Interconnection.
axial leads
Leads
on
a component that
are
arranged
to
protrude
along

a linear
axis
in
a
common
plane.
In
other
words,
they
stick out
the
ends
rather
than
out
the
sides.
axial ratioIn elliptically polarizedradiant
energy,
the
ratio
of
the
major
axis
to
the
minor
axis.

axial ray
See
axis
ray.
axicon
An
optical imaging element commercially
manufactured
as
a
conical
lens
(rotationally
symmet-
ric
prism)
with
the
capability ofconverting a
beam
of
coherent
light
into
a
ring
with
anondiffracting
cen-
tral

region.
Diffractive
axicons,
with
very
long
focal
lines,
may
be
applied
to
3D
imaging
technologies
and
have
been
demonstrated
for
generating
Bessel
beams
for
manipulating particles. Holographic
axicons
may
be
used
as

tools
for
generating
volume
intensity
dis-
tributions.
Collimation of
atomic
beams
was
accomplished
with
axicons
in
the
late
1980s
and
wider
commercial
dis-
tribution of
ax
icons
increased
in
the
late
1990s

and
early
2000s.
Commercial axicon
components
have
conical
polished surfaces,
come
in
a
number
of
stan-
dard
types,
and
may
be
used
in
conjunction
with
fo-
cusing
lenses.
Axicon
lens
cone
angles

are
typically
about
160
o
±20°. Bessel beams may be generated
through
axicon
lenses
in
the
micrometer-
and
milli-
meter-wave
ranges.
See
Bessel
beam,
laser.
axis
1.
A reference, orientation,
or
vector
in
a
coor-
dinate system, typically depicted
as

a line when
graphed.
See
normal.
2.
Aprimary direction
or
line
of
motion.
3.
An
imaginary or implied
line
around
which
other
elements
appear
to
be
oriented
as,
for
ex-
ample,
the
vertical
axis
ofa

tree
trunk
or
the
hori-
zontal
axis
ofa sea/skyscape.
4.
A
drawn
line,
usu-
ally straight, used
as
a reference
in
a
graph
or
chart.
5.
The
longitudinal
center
or
cross-sectional diameter
of
a
wire

or
cable,
commonly
referenced
for
size.
89
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
axis
ofrotation A
straight
line
around
which
a
body
or
representation
is
symmetrically
aligned
or
around
which
it
rotates.

axis
parabolic,
axis
paraboloidal
See
off-axis
para-
bolic,
on-axis
parabolic.
axis ray, axial ray In
fiber
optic
networks,
a
light
beam
or
ray,
from
a
laser
source,
that
travels
along
a
path
in
the

waveguide
that
is
coincident
with
the
axis
(longitudinal
center)
of
symmetry
of
the
light-guid-
ing
fiber.
See
fiber
optic
cable,
waveguide.
AZERTYA
designation
for
a
computer
keyboard
or
typewriter
keyboard

used
in
some
European
countries
such
as
France.
The
letters
represent
the
fITst
six
top
left
letters
directly
below
the
number/symbol
keys.
The
layout
is
essentially
an
adaptation
ofa
QWERTY

keyboard
with
slight
changes
to
accommodate
some
of
the
alphabetic
differences
in
European
languages
(e.g.,
extra
letters).
See
QWERTY.
azimuth
1.
A
geometric
arc
used
in
navigation
and
astronomy
which

is
calculated,
for
example,
between
a
fIXed
point
on
the
horizon,
and
clockwise
through
to
the
center
ofa
specified
object.
2.
A
horizontal
di-
rection
calculated
from
the
angular
distance

between
the
direction
ofa
fixed
point,
such
as
a
navigational
heading,
and
the
direction
of
the
object
(boat,
space-
craft,
etc.).
3.
A
specific
arc
described
in
relation
to
a

fIXed
point
and
a
moving
object
or
radiating
trans-
mission
such
as
a
rotating
storage
medium
(drive,
tape,
etc.),
or
antenna.
4.
The
horizontal
direction
of
a celestial
point
from
a

reference
terrestrial
point,
expressed
as
an
angular
distance.
Ayrton, Hertha Marks
(nee
Phoebe
Sarah
Marks
1854-1923)ABritish
physicist,
inventor,
and
author
who
investigated
electricity,
particularly
electric
arcs.
She
became
the
fITst
female
member

of
the
Institu-
tion
of
Electrical
Engineers
(lEE).
Ayrton
was
the
author
of
The
Electric
Arc,
published
by
Van
Nostrand
in
1902,
which
became
a
standard
textbook
on
the
subject.

In
1906
she
was
awarded
the
Hughes
medal
for
her
work
on
electric
arcs
and
on
90
sand
ripples.
Ayrton
was
awarded
a
patent
for
the
in-
vention
of
an

instrument
that
was
used
for
dividing
a
line
into
any
number
of
equal
parts.
E.
Sharp
pub-
lished
a
memoir
of
Ayrton
in
1926.
Hertha
Marks
Ayrton
- Physicist, Inventor
Hertha Marks Ayrton was an intelligentandversa-
tile observer, inventor,

and
author interested in the
physics andapplications
of
electricity. [ca. 1899
pho-
tograph courtesy
of
the Archives
of
the Institution
of
Electrical Engineers (lEE), London.]
azimuth-elevation mount A
common
type
of
an-
tenna
mount
that
facilitates
two
types
of
rotation,
for
adjusting
both
horizontal

orientation
(azimuth)
and
elevation
(height).
This
type
of
mount
is
frequently
used
with
parabolic
antennas
that
work
best
when
fo-
cused
precisely
toward
highly
directional
beams.
See
parabolic
antenna,
microwave

antenna,
polar
mount.
© 2003 by CRC Press LLC
~
symb.
Greek
letter
beta,
often
used
in
geometric
drawings
to
denote
a specific
angle.
May
also
repre-
sent
phase
constant
in
electrical
equations.
B
1.
symb.

magnetic
flux.
2.
abbrev.
brightness,
as
a
computer
monitor
or
TV
picture
tube
setting.
3.
symb.
byte,
a
unit
of
data
commonly
consisting
of
eight
bits.
See
byte.
Historic Dry and
Wet

B Batteries
Older wet B batteries (right), with the individual
battery cells connected in series, were cumbersome
and
awkward to handle. Historic wet cells were su-
perseded
by
more convenientdrybatteries (left). These
examples arefrom the American Radio Museum col-
lection. [Classic Concepts; usedwith permission.]
BbatteryA
low-voltage
source
of
direct
current
(DC)
power,
historically
used
to
provide
power
to
the
plate,
or
anode,
in
electron

tubes,
or
to
relays
in
a
communi-
cations
circuit.
Bbatteries ranged
from
about
22.5
to
130
volts,
with
48
volts
common
in
communications
circuits.
The
early B batteries
were
wet
cells,
often
consisting of a matrix

of
1.5-volt cells combined.
Later
dry
cells,
with
two
leads, replaced
the
more
cumbersome
wet
cells.
Most
had
snap
connectors,
but
some
had
4-pin
plugs.
While
B
batteries
are
no
longer
common,
there

are
still a
few
commercially
available,
ranging
from
22.5
to
67.5
volts.
Antique
radio
buffs
will
sometimes
wire
up
aseries ofcommercial9-volt
batteries
to
produce
the
functionality of
an
old-time
B
battery.
See
battery.

B Block A Federal Communications Commission
(FCC)
designation
for
a Personal Communications
Services (peS) license granted
to
a telephone
com-
pany
serving
a Major
Trading
Area
(MTA).
It
grants
permission
to
operate at certain FCC-specified
frequencies.
In
1994/95,
the
FCC
auctioned
Broad-
band
PCS
A

and
B
blocks
to
18
winning
bidders
for
total
revenues exceeding
$7
billion.
See
A
Block
for
a
chart
ofdesignated frequencies
for
Blocks
A
to
F.
B CarrierA local
wire
line
cellular telephone
com-
munications

carrier.
It
is
the
designation
for
the
local
phone
company,
although
the
cellular
system
may
be
sold offafter initial licensing
by
the
local
carrier.
B
Carriers
are
permitted
to
operate
in
four
stipulated

frequency
ranges
between
835
and
894
MHz.
See
A
Carrier.
B
channell.
In a stereo
system,
the
designation
for
the
right
audio
channel,
typically connected
to
the
right
speaker,
often
color-coded
as
red.

2.
bearer
chan-
nel.
A channel
in
a circuit-switched
ISDN
connec-
tion
with
bidirectional data transmission
capability.
For a fuller description,
see
ISDN.
B interface
An
interface used
in
Cellular Digital
Packet Data
(CDPD)
which
is
deployed
over
AMPS.
The
B interface

connects
the
Mobile
Data
Interme-
diate
System
(MD-IS)
to
the
Mobile
Data
Base
Sys-
tem
(MDBS).
See
Ainterface, C interface, Cellular
Digital Packet Data,
D,
E,
and
I interface.
B
minus,
B-
A negative terminal
on
a B
battery.

A
negative polarity
in
avacuum
tube
anode.
Bplus,
B+
Apositive terminal
on
aB
battery.
A
posi-
tive
polarity
in
a
vacuum
tube
anode
or
voltage
source
in
an
electronic transistor.
See
B
battery.

B port
In
a
Class
A,
dual-attachment
(dual
ring)
Fi-
ber Distributed
Data
Interface
(FDDI)
token-passing
network, there
are
two
physical ports, designated
PHY
A
and
PHY
B.
Each
of
these
ports
is
connected
to

both
the
primary
and
the
secondary ring
to
act
as
a
receiver
for
one,
and
atransmitter
for
the
other.
Thus,
the
B port
is
a transmitter
for
the
primary
ring
and
a
receiver

for
the
secondary
ring.
The
dual
ring
system
is
configured
to
provide
fault
tolerance
for
the
net-
work.
FDDI
ports
can
be
connected
to
either
single
mode
or
multimode fiber
optic

media,
providing half
du-
plex
transmissions.
LEDs
are
commonly
used
on
port
adaptors
as
status
indicators. Optical
bypass
switches
may
in
tum
be
attached
to
the
port
adaptors.
Optical
bypasses
are
provided

to
avoid segmentation
which
might
occur ifthere
is
a
failure
in
the
system,
and
a
station
is
temporarily
eliminated.
See
dual
attachment
91
© 2003 by CRC Press LLC