It is used for security or efficiency monitoring, frequently on touchtone phone systems to pennit long-distance calls or gather departmental data.. Sophisticated telephone sys-tems can b
Trang 1Fiber 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-ment SatelliteARIES Alow Earth orbit (LEO) sun-synchronous satellite project for deploying a hyperspectral sensor capable ofidentifying details of the Earth's surface that cannot be sensed by other types ofinstruments 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 ofExploration 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 timeline was es-tablished for it to become operational in 2001 (since delayed to 2002) A vertical tracking spatial resolu-tion of 30x30 meters is possible on the system, which can be increased by viewing sideways or im-proved when resolving certain high-contrast objects http://www.eoc.csiro.au/aries/
Australian Speech Science and Technology Asso-ciation IncorporatedASSTA Anonprofit scientific association seeking to advance research and under-standing of speech science and its application in speech technologies for the benefit ofAustralia authenticateTo establish the identity and authori-zation status of a user, device, process, or data seek-ing entry to a system or seekseek-ing 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 accessAbasic 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 transmittedastext that can potentially be captured and read See authenticate; authentication, digest ac-cess; RFC 2617
authentication, digest accessA means to provide improved security for HTTP user authentication over
basic access authentication. See authenticate, RFC 2069
authenticatorIn 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
• , ~ "#19~' tllII.t~
FI& I-alN.HECTIONB amMa TWO
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.Itfalls within the
Com-munications, Information Technology and the Arts
portfolio http://www.aca.gov.au/
Lee de Forest invented the Audion through trial and
error and didntfully understand why it worked; thus,
it was difficult to commercially manufacture
consis-tently reliable tubes Edwin H Armstrongs
explana-tion ofthe workings ofthe Audion, published in
Elec-trical World in 1914, provided the theoretical
back-ground needed to improve manufacturing consistency
and hence practical applications ofthis important
in-vention See Audion.
rorranIAL
Australian Computer Societysee computer
societ-ies, national
Australian Institute of Computer EthicsAlCE.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
Trang 2to 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
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
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
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
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
calland may be rejected or fOlWarded to someone in
authority
re-lease, or represent the product or services of a
com-pany in a somewhat cooperative, independent
man-ner with state restrictions.Itis 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 serser-vices.Insome cases,
the agent is a software developer or Internet Services
Provider (ISP) who works with the phone company
to provide digital value-added services
company or provider to use a service, system, or
spe-cific application or data file This concept is
impor-tant in communications security
receiving device to automatically detect and respond
to an incoming transmission Facsimile machines,
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 Callerill,to display the person's file on a computer monitor See Caller ID, Caller Name, bulletin board system, auto dial
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
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 ofnumbers, 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 Re-dial for voice communications See auto dial
short code has been assigned to a longer number to allow the number to be dialed automatically with fewer keystrokes See abbreviated dialing
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, a cellular 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 ofautomated pro-cedures for phone solicitations See auto answer
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
Trang 3Fiber 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
outage or power fluctuation sufficient to take down
the system
more entities, the process ofsetting 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
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
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
of a 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 1OOBASE-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 1OOBASE-TX
standard, an emulation system for a link pulse was
devised for fiber-based transmissions, with
adjust-ments for the different timing needs offiber 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
services like BBSs and on systems that may be serv-ing a variety of types of computers 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 of computers and modems
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
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
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 system AVRS A system designed to respond to voice commands without the intervention of a 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 Directory Assistance Can Completion
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 Directory Assistance Service ADAS A commercial telephone service in which a speech rec-ognition system is used to get information from a
Trang 4quests 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 If a caller 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
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 a regular basis (e.g., once a day),
usu-ally during low traffic times
Automated Maritime/Marine
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 oflicenses for over 4000 channels serving the
Gulf Coast and Ohio River barge industry Thus,
Mobex became a significant provider ofmarine
mo-bile radio services in North America
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 ofDefense and subsequently transferred
to the Telos Corporation for servicing requests
Automated Packet Recognition/Translation
APaRT ACisco 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, ifnecessary,
translates specific data link layer encapsulation
packet types
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, ifthe primary route
is unavailable, without user intervention
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
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.AnACD 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 callsacco~dingto 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
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
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
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
ef-ficiency feature available to private branch exchange (PBX) telephone subscribers ACA evaluates and re-ports on phone trunk usage or malfunctions Trunks
~ :.~••.;.:•.:.•.; •.•.1 • ~••:~.•.: .
,~1 •
Trang 5Fiber 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 a potential problem
is detected, an attendant is notified
Australian association of companies involved in
manufacturing, distribution, and consulting for the
data capture industry ADCA promotes the
develop-ment and maintenance ofstandards 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
http://www.adca.com.au/
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
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
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
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 ofnot 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
subsequent stations, nodes, or consoles are excluded
from having access to the line
sam-pling of a 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 Adevice that can seek a particular 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 A circuit 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
opera-tor of a 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
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 ofgoods in shipping and inven-tory management systems in many distribution and retail businesses In March 2001, the U S Defense Logistics Agency published theDefense 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
multiline phone option that records the extension number ofthe originating phone in order to facilitate billing AlOD is especially common for the identifi-cation of long-distance calls AlOD leads are termi-nal leads used to transmit this information to the phone carrier
types ofcameras, 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
Trang 6contrast, 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
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
com-munications and computer networking, the
capabil-ity of a system to negotiate automatically a
connec-tion between two or more staconnec-tions 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
emergency systems that automatically provides
in-formation on the source of the call from a database
Anet-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 ofsystem 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
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 ofphone 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 ofthe
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
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 Callerillby the number ofrings within which the information was sent to the caller, but that distinction is disappearing See Caller 10, Signaling System 7 2 A multifrequency signaling parameter
by which a long-distance carrier receives the caller's number from the local carrier for billing purposes
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
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 ifexcessive 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
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 If a connection is made, a ring alerts the user to the completed connection
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
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 ifthe 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
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
Trang 7AUUGAustralian Unix User Group.
AUXBC auxiliary broadcasting
signed to carry out many ofthe 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 A circuit 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 ofautomation 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 theciscoBus 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 a collective numbered common domain The ASN designates a system under common opera-tions control, using common routing protocols, with the various routing tables dynamically maintained
type identifier (PTI) field bit used with AAL5 to in-dicate the end of a 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.Inits 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
of a set length, and the sender waits for an
acknowl-edged (ACK) or not acknowlacknowl-edged (NAK) signal (or
no response) before retransmitting or continuing.In
some systems, such as amateur radio
communica-tions, ARQ is calledmode 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 acknowlacknowl-edge (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 teletele-phone 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 MarkI
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 a user'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-no congestion
no congestion congestion congestion
AUUO AUUl AUUO AUU 1
bit pattern 000 001 010 011
Trang 8telephone or network system is available for handling
Position-ing Service (GPS), the period oftime durPosition-ing which a
particuhtt location, within angle ofelevation
param-eters, has sufficient satellites to make a position fix
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 of existing local area
network (LAN) protocols In network
implementa-tions, there is generally an Available Bit Rate (ABR)
command that facilitates the configuration of peak
and minimum cell rates in kilobits per second See
cell rate, constant bit rate, variable bit rate
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
situ-ation in which sufficient high-voltage energy is
gen-erated by some carriers such that others are
physi-cally impacted
elec-tronic image or other embodiment of an individual
that is computer-generated and holds some essence
or presence of individuality or actuality beyond that
of a photographic image or scan This concept is
prevalent in the imaginary world of computer
gam-ing (and Internet chat areas), especially in virtual
re-ality simulations
AVD See alternate voice data
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 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
admin-istrative statistic describing average bandwidth usage
over a specified period of time The information is
useful in managing bandwidth in a multichannel
system
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
radi-ometer
aside for aviation communications and aviation-re-lated signaling/sensing purposes (e.g., radar)
AVRS See automated voice response system
Conver-gence Sublayer
System
for Women Geoscientists 3 Association ofWashing-ton Geographers
Unix systems, developed by Aho, Weinberger, and Kernighan (who is also an author ofC) It has a C-like syntax See Perl
packet radio communications that operates at the link
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
to protrude along a linear axis in a common plane In other words, they stick out the ends rather than out the sides
ratio of the major axis to the minor axis
manufactured as a conical lens (rotationally symmet-ric prism) with the capability of converting a beam ofcoherent light into a ring with a nondiffracting 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 ofatomic beams was accomplished with axicons in the late 1980s and wider commercial dis-tribution of axicons increased in the late 1990s and early 2000s Commercial axicon components have conical polished surfaces, come in a number ofstan-dard types, and may be used in conjunction with fo-cusing lenses Axicon lens cone angles are typically
through axicon lenses in the micrometer- and milli-meter-wave ranges See Bessel beam, laser
coor-dinate system, typically depicted as a line when graphed See normal 2 A primary 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 of a tree trunk or the hori-zontal axis of a 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
Trang 9Fiber Optics Illustrated Dictionary
axis of rotation 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
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
AZERTY Adesignation 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
astronomy which is calculated, for example, between
a fIXed point on the horizon, and clockwise through
to the center ofa specified object 2 Ahorizontal
di-rection calculated from the angular distance between
the direction of a fixed point, such as a navigational
heading, and the direction ofthe object (boat,
space-craft, etc.) 3 Aspecific 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
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 ofThe Electric Arc, published
by Van Nostrand in 1902, which became a standard
textbook on the subject.In1906 she was awarded the
Hughes medal for her work on electric arcs and on
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 ofAyrton in 1926
Hertha Marks Ayrton - Physicist, Inventor
Hertha Marks Ayrton was an intelligent and versa-tile observer, inventor, and author interested in the physics and applications ofelectricity [ca
1899pho-tograph courtesy of the Archives ofthe Institution of Electrical Engineers (lEE), London.]
an-tenna mount that facilitates two types ofrotation, 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
Trang 10drawings to denote a specific angle May also
repre-sent phase constant in electrical equations
byte, a unit ofdata commonly consisting ofeight 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 convenient dry batteries (left) These
examples are from the American Radio Museum
col-lection [Classic Concepts; used with permission.]
B battery Alow-voltage source ofdirect current (DC)
power, historically used to provide power to the plate,
or anode, in electron tubes, or to relays in a
communi-cations circuit B batteries 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
common, there are still a few commercially available,
ranging from 22.5 to 67.5 volts Antique radio buffs
will sometimes wire up a series 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
band PCS A and B blocks to 18 winning bidders for total revenues exceeding $7 billion See A Block for
a chart of designated frequencies for Blocks A to F
B Carrier A local wireline cellular telephone
phone company, although the cellular system may be sold off after 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
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 bidirecconnec-tional 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 A interface, 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 a vacuum tube anode
B plus, B+ Apositive terminal on a B battery Aposi-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 a transmitter 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 if there is a failure in the system, and a station is temporarily eliminated See dual attachment