time-space processingAlso called temporo-spatio processing, this type of processing is used in appli-cations and devices such as infrared motion detec-tors or radar systems which are usi
Trang 1Fiber Optics Illustrated Dictionary
commonly used with audio/visual recordings that will
later be edited, dubbed, or otherwise manipulated or
played within strict time constraints Time code is
typically stored as hours, minutes, seconds, and frames
Time code was developed in the late 1960s when
ana-log recording tapes became prevalent, in many cases
replacing film The system was developed because
video tape lacked the sprockets which previously had
been used on film to synchronize sound and images
In the 1990s, another transition was made from
ana-log video tapes to digital recording technoana-logies, and
the time code techniques used for analog video and
audio encountered certain problems when applied to
digital recording technologies See chase trigger,
MIDI time code, reference clock, SMPTE time code
Time Division Multiple AccessTDMA A digital
technology designed to overcome some limitations
ofanalog cellular mobile communications Time slot
assignments allow several calls to occupy one
band-width, thus increasing capacity for various wireless
technologies E-TDMA (Extended TDMA) provides
even more time slots TDMA is widely supported by
AT&T Wireless Services.Itis similar to Code
Divi-sion Multiple Access (CDMA) See Demand
As-signed Multiple Access
There are a number ofTDMA implementations, with
three primary ones: European TDMA (GSM),
Japa-nese TDMA (PHS/PDC), and North American
TDMA (18-136) See AMPS, DAMPS, cellular
phone, time division multiplexing
time division multiplexingTDM A technique for
combining a number of signals into a single signal
by allocating a time slot in the combined signal with
a multiplexer At the receiving end, a demultiplexer
is used to separate the interleaved signal back into
its original signals Some of the early developments
of this technique were accomplished by J.M.E
Baudot in the 1870s In current usage, TDM allows
a variety of types of communications, audio and
video, to be transmitted at the same time in one
in-terleaved signal
time signalsFrom around the mid-1800s before time
zones were established, to the present day, people
have sought to devise ways to determine the time and
synchronize their activities The first time signals
were drums or bells that were regularly sounded in
local communities based upon the sun's position
Later, in the 1860s, the U.S Naval Observatory used
the telegraph to transmit time signals, and soon
West-ern Union was sending standard time signals, a
tra-dition they continued for a century Telegraph time
signals were similar to current Coordinated
Univer-sal Time signals, in that audible clicks were used
com-ing up to the hour, just as tones now signal the
up-coming minute See Coordinated Universal Time,
Greenwich Mean Time
Time TAnlTU-T designation for 2359 hours
Coor-dinated Universal Time (UTC) on 31 December 1996
time-delay modulationIn optics, a form of phase
modulation signal encoding the involves modulating
a signal in the luminance channel with delays between
pulses as the "carrier" signal
time-space processingAlso called temporo-spatio processing, this type of processing is used in appli-cations and devices such as infrared motion detec-tors or radar systems which are using time and space
as interrelated factors in their decision-making in terms of processing data or signaling an alarm con-dition Time-space processing is also used in adap-tive beam-forming antenna mechanisms
time-to-digital converterTDC.Aninstrument for sampling a short time interval between two electri-cal signals, usually in pico- or nanosecond resolu-tions TDCs are useful for measuring the leading edge ofthe time interval between transmitting and receiv-ing pulses for tunreceiv-ing, maintainreceiv-ing, and troubleshoot-ing electrical systems They may also be used for detectors, imaging systems, laser rangefinders, and time-of-flight measurements In clock correction sys-tems, a TDC may be installed between a local clock and a processing system that derives optical data from theTDC
There are tradeoffs in timing resolution and linearity between digital and analog interpolation methods used with TDC data
Commercial TDCs typically include LEDs for dis-playing status and may support multiple independent channels (usually 4, 8, or 16) For longer time inter-vals, a counter and oscillator may be used
timingConfiguration of a system so successive rep-etitions are controlled for the desired interval (which may be desired to be variable), or so certain events begin and!or end at designated times or according to certain events Timing is important in magnetic stor-age mechanisms, motors, signal amplitude sequences
in electronics, and broadcast equipment configura-tions Timing is also important on networks, where, for example, video and audio signals may be sent separately or on separate lines, but have to be coor-dinated at the end to provide services like videoferencing Constant oscillators are often used in con-junction with very precise timing devices See atomic clock, quartz, SMPTE time code
timing signal1 A signal generated according to an accepted standard of time, usually for the purpose of providing a precise or obj ective baseline against which to measure events 2 A signal generated by measuring some repetitive event which is then com-pared to some standard or clock 3 A signal simulta-neously recorded with data to provide a measure or standard against which the data can be analyzed 4 A regularly emitted signal against which other time-re-lated events can be synchronized
TINATelecommunications Information Networking Architecture Anetworking telecommunications soft-ware architecture intended to be developed into a glo-bal standard See Telecommunications Information Network Architecture Consortium
TINA-CSee Telecommunications Information Net-work Architecture Consortium
tinned wireWire that has been treated with tin to provide insulation and/or to facilitate soldering Com-mon on copper wire
tinselAfine, very long thread or strip ofmetal
Trang 2some-the insulator and some-the main core or wire Because of
its properties, tinsel is used in cables that need to be
tightly wound or very flexible (such as phone
hand-set cords)
tintLighter or darker values ofa particular color; hue
Tints are created by successive additions ofwhite or
black pigments, or by successively increasing or
de-creasing values of red, green, and blue (RGB) at the
same time Greater amounts of each color of RGB
will produce lighter tints and lesser amounts will
pro-duce darker tints
tip 1 The line or connection attached to the positive
side of a circuit or battery 2 In two-wire telephone
wiring, the tip is traditionally the green wire attached
to the positive side ofthe circuit at the central
switch-ing office The name originates from the
configura-tion of a manual phone jack in an old telephone
switchboard in which the large plug was divided into
two sections, with an internal wire electrically
con-nected to thetipof the plug, and another wire to the
ring around the plug partway up the jack nearer the
insulated cord See ring, tip and ring
tip and ringHistorically, the tip and ring
designa-tions derive from the configuration of a phone jack
from a manual switchboard, called a cordboard The
tipwas the positive circuit connected to the tip ofthe
jack, and the ring was negative, located slightly away
from the tip encircling the jack, sometimes called
"sleeve." Later the tip and ring became standardized
to correspond with the green and red color-coded
wires traditionally used to install phone line services
Often telephone wire is composed offour wires with
red, green, black, and yellow sleeves Since dual lines
have become more common in small businesses and
in some homes, the black and yellow lines are used
for tip and ring, respectively, for the second line
While these codes are standardized in North America,
there are variations in other countries and in larger
installations with multiple phone lines
tip jack, pup jackOne ofthe simplest connectors, a
tip jack has a single, usually round, contact point plug
that fits into a matching single-hole plug
TIPHONSee Telecommunications and IP
Harmo-nization Over Networks
TIRKSTrunk Inventory Record-Keeping System A
commercial product from Telcordia that aids in
plan-ning, inventorying, and assigning the telephony
cir-cuit order control and circir-cuit provisioning of
inter-office equipment and facility inventory FEPS is a
component of TIRKS that provides a range of
auto-mated software tools for planning and provisioning
interoffice facilities and transmission equipment
TIROSTelevision Infrared Observation Satellite A
historic series of global polar-orbiting meteorological
satellites developed by GSFC, built by RCA, and
managed by the Environmental Science Services
Administration (ESSA) It was followed by the
TIROS Operational System (TOS), then by
Im-proved TIROS (ITOS), and subsequently the NOAA
satellites The TIROS spacecraft included
low-reso-lution television and infrared cameras
and 1965 into low Earth orbits TIROS-N was launched in 1978 In general, they looked like cylin-drical "mirror balls," studded as they were with so-lar cells, and were about the size ofan oil barrel sliced
in half Spiny leglike antenna protruding from the flat end of the cylinder gave them an insect-like look TIROS systems provided the first meteorological data for weather forecasts that were received from space Continuous coverage of the Earth's surface began in
1962 and proved the feasibility ofspace data for me-teorological research and forecasting
Remote-Sensing Satellite
An artistsconception ofthe antennas, sensors, and solar cells in the TIROS7meteorological satellite, as envisioned in April1961. {NOAA In Space Collec-tion.]
TIROS NINOAA ProgramAremote-sensing satel-lite program based on the TIROS satelsatel-lite series that was initiated to improve upon the operational capa-bilities of the original TIROS numbered series from the 1960s and its successors in the 1970s
In contrast to the earlier barrel-shaped TIROS sys-tems, the TIROS-N satellites were longer and more rectangular, and about three times larger The systems were three-axes stabilized and Earth-oriented Improvements in sensing technologies and solar power were incorporated into the later TIROS/N se-ries which includes a number ofsuccessful and failed satellites beginning in 1978 and continuing into the late 1990s and present ITROS-N satellites carried the Advanced Very High Resolution Radiometer (AVHRR) for day and night sea surface and cloud-top sensing.Anatmospheric sounding system was also included, as well as a solar proton monitor to detect energetic particles from the Sun that might sig-nal an upcoming solar storm
1itanic, RMSThe famous, ill-fated ''unsinkable'' ship
that sank in 1912, with hundreds of lives lost, while crossing through ice fields north of Canada The ra-dio operator oftheTitanicsent distress calls, but two ofthe closest ships dido't receive the communications,
as 24-hour watch programs and radio regulations had
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not yet been established (this changed after the
sinking of theTitanic) Fortunately, however, some
of the sea-goers were saved by theCarpathia, who
came to their rescue after receiving the radio distress
call
The sinking of theRepublic, an earlier ocean-going
ship, had a strong influence on legislation requiring
wireless communications systems to be installed on
ocean-going vessels Due to the wireless distress
calls, all but two of the hands on theRepublic were
saved The sinking of theTitanic resulted in further
legislation associated with keeping those
communi-cation lines open and monitored 24 hours a day See
the JASON project, MARECS, MARISAT
TL See tie line.
TLD See top level domain.
TLF See trunk link frame.
TLP See transmission level point.
TLS transparent local area network (LAN) service.
TLS Protocol See Transport Layer Security
Proto-col
TLV type, length, value An encoding approach used
in Basic Encoding Rules for the information content
of elements
TM I terminal multiplexer 2 traffic management.
A term associated with network transmission cell
traf-fic flow, monitoring, and control See cell rate
TMA Telecommunication Managers Association.
See Communications Management Association
TMC traffic management center.
TMGB See telecommunications main grounding
busbar
TMN See Telecommunications Management
Net-work
TMS 1000 A one-chip 4-bit microcomputer
intro-duced by Texas Instruments in 1972 Arguably the
second microcomputer ever released with the Intel
MCS-4 chip set, it never gained popularity
TMSI See Temporary Mobile Station Identifier TOGAF See The Open Group Architectural
Frame-work
toggle 1 In general, a two-state process or switch.
2 Flip-flop An electrical current that alternates in in-tensity at two distinct levels, or which has two states:
on or off 3 In software applications, a button or icon that has two states or positions 4 In computer pro-gramming, a flag that is either set or not set, on or off Toggles are very commonly used to keep track
of software configuration settings
toggle switch A switch that moves between two
po-sitions typically representing two states: on/off, high! low (Three-state switches are sometimes also loosely referred to as toggle switches.) A traditional buildinng switch that turns a light on or off(in contrast to a dim-mer switch) is a common type of toggle switch
In aviation and audio equipment, a small narrow switch rounded on the end and tapered more finely
at the point of attachment, roughly the shape of a baseball bat is sometimes called a bat switch This type of switch is common in the aviation and audio industries where quick toggle adjustments are needed and many components are crowded for space in a small area
token On a Token-Ring network, a status/priority
information block used in coordination of traffic on the network A token consists of a 24-bit frame that operates at the Media Access Control (MAC) level
It is continually passed around the ring in one direc-tion and consists of a start delimiter (SD), an access control (AC) field, and an end delimiter (ED) Most
of the information for controlling events is contained
in the AC It is further subdivided into a 3-bit prior-ity field, a token bit (zero indicates it is a token), a monitor bit, and a 3-bit reservation field that lets the
Token-Ring Basic Frame Components
Starting Delimiter SD Indicates the beginning of a frame
Access Control AC Contains the Priority, Token, Monitor, and Reservation bits In a
frame, a workstation can only change the Reservation bits in the access control field Only the active monitor can change the "M" bit, and only the workstation or device changes the Token bit
Frame Control FC Indicates the type of frame: data frame or maintenance frame A
maintenance frame is used by the protocol to manage the ring
Destination Address DA Physical or NrC address of the receiving workstation or device
Source Address SA Physical or NIC address of the sending workstation or device
Information Layer control, routing control, and data
Frame Check Sum FCS Error checking at the destination
Ending Delimiter ED Indicates the end of a frame If one of multiple frames or the last
frame in a transmission, it's an I bit; if an error occurred, it's an E bit Frame Status FS Indicates if a frame has been recognized and copied by the
destination station
Trang 4sion of frames Atoken is reissued after use by a
sta-tion ofthe suitable priority, and continues on its way
See token-passing, Token-Ring frame, Token-Ring
network
Token-Ring interface couplerTIC A Token-Ring
local area network (LAN) port that is typically
in-stalled on a computer peripheral network interface
card(NIC) The TIC facilitates the connection ofthe
computer to the local network
token latencyIna token-passing scheme, the time it
takes for the token to make it all the way around a
token-passing local area network See token-passing,
Token-Ring
token-passingA process on a Token-Ring network
by which status/priority tokens are used as a
mecha-nism to coordinate traffic around the unidirectional
ring Atoken is a 24-bit frame that operates at the
me-dia access control (MAC) level It consists of a start
delimiter (SD), an access control (AC) field, and an
end delimiter (ED) The token-passing continues
around the ring where each station checks the
prior-ity before adding frames to the traffic on the ring
Once a token has been used, assuming the proper
pri-ority, it is sent out again by the transmitting station
to continue its journey around the ring through each
station, carrying out the same sequence ofevents,
ac-cording to priority levels
Token-Ring frameAToken-Ring frame in the IEEE
802.5 specification consists ofthe components
speci-fied in the Token-Ring Basic Frame Components
chart
Token-Ring Interface ProcessorTRIP A Cisco
Systems high-speed interface processor with two or
four Token-Ring ports, which can be independently
set to speeds of 4 or 16 Mbps
Token-Ring networkTR network A local area
net-work developed by IBM in the mid-1980s, based
upon a star or ring topology, that is, with nodes
nected either directly to one central hub, or in a
con-tinuous loop not requiring termination The
token-passing is a scheme for data transmission between the
stations which prevents collisions from different
workstations sending messages at the same time A
workstation cannot transmit until it receives
permis-sion, that is, a token of the proper priority The token
is passed from station to station around the ring in
one direction At each station, the priority is checked
before a frame is transmitted on the ring
Token-Ring uses a source-routing system that moves
information among stations based upon information
in data packet headers, thus utitizing inexpensive
bridges, a system different from Ethernet LANs
Speeds are up to about 16 Mbps, a limitation that has
been addressed in High Speed Token-Ring, and
throughput is about 60 or 70%, somewhat higher than
Ethernet Frames hold about 4000 bytes Token-Ring
LANs are sometimes combined with Ethernet LANs
They typically run over copper twisted-pair cables,
although some are now implemented with fiber
Since IBM's introduction, Token-Ring has been
de-veloped into a Media Access Control (MAC) level
A Fiber Distributed Data Interface (FDDI) network employs various token-passing concepts using dual rings to provide redundancy and fault tolerance See Ethernet, Fiber Distributed Data Interface, High Speed Token-Ring, ring topology, topology
TokenTalkAn Apple Computer Macintosh-based implementation ofa Token-Ring local area network See AppleTalk, Token-Ring network
toll callAny call to a location outside the local ser-vice area, so called because it is billed at a rate above and beyond the local subscriber service A long dis-tance call
toll denialDenial ofservice outside the local service area Toll denial may be part of a private exchange
in order to limit calls to local calls, except as autho-rized Toll denial may also be set up on an individual subscriber line (e.g., a subscriber who is behind in payments on long distance charges), or a line in a col-lege dorm, or other location where potential toll abuse
or fraud may occur It may still be possible to make toll calls by going through an operator or entering authorization codes See toll diversion, toll restriction toll saverAfeature ofanswering machines and some computer software programs that lets you call into
an answering machine from a long distance location
and know whether there are any messages before the
line is connected The system is based upon the num-ber of rings, usually four or two With toll saver en-abled, if there are no messages, the answering sys-tem will ring four times before answering If there are messages, it will answer on two rings That way,
if the caller hears three rings, there are no messages, and he or she can hang up before the machine answers
on the fourth ring and save the long distance charge toll terminalA phone system set up only for long distance calls (toll calls) Toll terminals expedite
a secure location, accessible only to authorized callers tone above bandTAB A form of linear broadcast signaling used in conjunction with single sideband suppressed modulation.InTAB, corrections are ap-plied to the received signal, as needed, to produce recognized pilot tones above the frequency of an in-formation signal (as opposed to its center), to correct the accompanying information signal Transparent tone above band (TTAB) is the same essential idea except that the tone is explicitly chosen to be outside the hearing range audible to humans See tone in band
tone dialingAsystem ofaudio tones called dual tone multifrequency(DTMF) used to generate distinct sig-nals with which phone numbers and symbols can be transmitted Frequencies are selected in such a way that dual tones are not harmonically related Each tone
is actually a combination of two tones, high and low, which are decoded when sent down the line to the switching office The high tone is usually slightly louder than, or at least as loud as, the low tone The tones range in frequency from about 697 to 1633Hz Two advantages of tone over pulse dialing are speed
Trang 5Fiber Optics Illustrated Dictionary
and flexibility As direct-dial long-distance services
became available, numbers became longer, and it
takes more time to dial a number on a pulse phone,
partly because of the mechanical act of rotating the
dial and partly because the dial has to return to the
base position Touchtone systems also provide more
options With a combination ofdigital processing and
touchtone signals, automated menu systems can be
accessed through the phone These are now widely
used by banks, mail order houses, and others See
pulse dialing, DTMF, touchtone dialing
tone generator Any device or software application
that generates tones These may be at a particular
fre-quency or may vary Tones can be generated in the
audible frequency range for humans, or higher ranges
for electronic detection Tone generators may be used
as diagnostic devices on telephone networks See
buzzer
tone in band TIB A form of linear broadcasting
modulationinwhich corrections are applied to the
received signal, as needed, to produce recognized
pilot tones at the center of a baseband information
signal, thus makingitpossible to correct the
accom-panying information signal FolWard signal
regenera-tion may be used to enhance TIB Linear modularegenera-tion
techniques provide narrower channels than frequency
modulation techniques, thus making it possible to
increase the number ofchannelsin a specified amount
of space
By the mid-l 980s, transparent tone in band (TIIB),
which uses a tone frequency inaudible to the user, was
being developed for use in mobile radio networks, for example, to help reduce fading loss
TTIB has become a standard in North America and Europe See linear modulation, tone above band tone probe A network diagnostic device for testing voice and other audio networks by detecting and am-plifying acoustical signals The probe may be passive, detecting only existing signals, or may be active, sounding a tone that is read by a detector somewhere else on the system or by the probe generating the tone (which can then read the echo)
tone receiver unit TRU The electronics in a tele-phone receiver which detect and interpret touchtone codes
TOPSee Technical Office Protocol
top-down An organizing or processing hierarchy that distributes itself downward, usually in a branching pattern Top-down often implies higher priority or more generalized functions or items at the top of the hierarchy Thus, a top-down outline lists more impor-tant concepts first, a top-down personnel chart usu-ally shows executive managers at the top, a top-down phone system starts with priority-listed agents, etc Top Level Aggregate TLA.AnIPv6 prefix and a cov-eted commodity to the Internet community, the pro-posed assignment of Top Level Aggregates to privi-leged companies caused controversy To quell the objections, TLAs were significantly increased and TLA requirements were removed from the IPv6 specification Many Internet developers are con-cerned with preventing the development of a VIP
Network Topology Examples
r~.·I.·
LzI
These are three common topologies for interconnecting local area networks (LANs).
The star topology (A) is a popular way to interconnect computers, printers, and other peripherals with signal negotiations through a central hub (e.g., "thick" Ethernet). If a system on the network becomes nonfunctional, the network as a whole continues to intercommunicate.
The ring topology (B), as in Token-ring networks, is an older network topology that is still used in many LANs In its simplest configuration, it is notfault-tolerant, however; if one system goes down, the network goes down, due to the missing link in the ring In FDDI ring-based networks, there are dual rings to provide redundancy in case ofa break in the link in the main ring.
The bus topology (C) is popular with daisy-chainable peripherals and with "thin" Ethernetworks that don t have too many systems attached It is also used in certain backbone connections with LANs as the tributaries The ends of the network are typically be terminated on bus topologies to inform the system that there are no more devices beyond
a certain point.
Trang 6top level domain TLD A hierarchical subset of the
domain name system (DNS) which has been further
subdivided into generic top level domains (gTLDs)
and country code top level domains (ccTLDs) The
distinction is administrative rather than functional;
TLDs all theoretically have the same access and
con-nectivity to the Internet Within individual
designa-tions, some domain name extensions are open and
some are restricted For example, the popular com
designation used primarily for business entities is
unrestricted, whereas the.govdesignation is restricted
for assignment to u.S federal government agencies
Country code TLDs are open or restricted to varying
degrees depending on the country maintaining the
designation Country code TLDs include ca for
Canada, uk for the United Kingdom, au for
Austra-lia, etc By 1999, it was estimated that almost 100,000
domain names were being registered per month, with
demand steadily increasing See the Appendix for a
list of domain name extensions
topology, network topology A schematic
represen-tation and configuration of the geometric and
electrical connections and relationships ofa network
and its various routing components Depending upon
the number of servers, terminals, routers, and
switches, a variety of possible configurations are
practical, including token rings, stars, and others See
backbone, mesh topology, node, star topology See
Network Topology Examples diagram
Topology Database Update TDU The refreshing of
interconnections and routing information within a
network system to reflect the current connections
The Topology Database may have upper limits as to
the number ofnodes that can be specified to describe
the system.Inmany systems, there are commands for
querying the Topology Database parameters and logs
as well as commands for setting the basic operating
parameters For example, the frequency of updates
may be logged to help a system administrator
deter-mine if configuration parameters are optimally set
topology management In networks, the
configura-tion, tracking, and management of connecting
de-vices, particularly switches The software used to
manage them will often show graphical images ofthe
various devices and their interconnections in the
system
TOPSSee Traffic Operator Position System
Torricelli, Evangelista (1608-1647) An Italian
physicist and mathematician who invented the
torricellian tube, now known as a mercury barometer
Barometers later became important in weather
fore-casting and in altitude-measuring instruments,
par-ticularly for aeronautics and ionospheric
experimen-tation The technology was also important in the
evo-lutionary development of the vacuum tube, the basis
for electronics for many decades until transistors and
semiconductors were developed
ToS See Type of Service
total internal reflection In a light-guiding cable, the
total reflection resulting when light rays guided
through awaveguide (e.g., fiber optic filament) impact
nal waveguide For example, in a fiber optic cable, the cladding has a slightly lower refractive index than the conducting core When light impacts the cladding
at angles that are not too steep (beyond the critical angle), the difference in the refractive index causes the light beam to reflect back into the light core
Total internal reflection is not limited to fiber optic cables It is characteristic of any optical component that has refractive quantum interactions at the inter-face between optical components R.W Woods was one of the first to document some unusual refractive properties in metallic surfaces,in1902 See refrac-tion; surface plasmon resonance; Woods, R.W
Total User Cell ruC In ATM networking, a recur-ring count of the transmitted Cell Loss Ratio (CLR), stored in the ruc field The information is useful in assessing throughput The CLR may be calculated using the Total User Cell (ruC) and the Total Re-ceived Cell (TRC) counts
touchscreen A specialized computer monitor which
is activated by contact with a finger or pointing in-strument The idea was that it was more natural for people to point than to use a mouse ofkeyboard Un-fortunately, holding an arm up for any length of time
is uncomfortable, so touchscreens haven't become popular for extended or repetitive work However, they are suitable for occasional input, as in kiosks and directory systems, and for some types of childhood education
Townes, Charles Hard (1915- )An American physi-cist and professor, Townes joined Bell Laboratories
in 1933 and worked there until 1947 after which he became a professor at Columbia University Begin-ning in the early 1950s, Townes became a significant pioneer in maser/laser technology and collaborated
on many projects with Arthur Schawlow A number ofhis students and those who interacted with Townes
in the Columbia lab also distinguished themselves in subsequent laser technologies
In 1961, Townes became a professor and Provost at MIT and stepped down from Provost in 1966 to devote more time to research In 1967, he became a profes-sor at the University of California (Berkeley)
Townes has received many awards for his work, most significantly a Nobel Prize in physics coawarded in
1964 Since 1980 the Optical Society ofAmerica has annually awarded the Charles Hard Townes Award for outstanding work in quantum electronics See Basov, A.; Capasso, F.; laser; laser history;
Prokhorov, A.; Schawlow, A
TP1 test point 2 transaction processing 3 transport protocol 4 twisted pair
TPASee Telephone Pioneers ofAmerica
TPDUSee Transport Protocol Data Unit
TPEXtwisted pair Ethernet transceiver
TP.See tracks per inch
TPOSSee Training, Planning & Operational Sup-port
TPWGSee Technology Policy Working Group
TQM total quality management Amanagement phi-losophy and means ofputting it into action to develop
i., • '.'."
:)
~:~~
Trang 7Fiber Optics Illustrated Dictionary
and maintain quality principles in commerce, service,
and manufacturing Quality assurance and ISO-900x
certification are two kinds of tools in the TQM
arse-nal See ISO 9000
TR transmit/receive
tracerA diagnostic tool for tracing a link through a
circuit.Infiber optics, a tracer shines a visible light
into the lightguide so a technician can check whether
it is following the appropriate path and making it all
the way through the lightguide (e.g., there are no
breaks or excessive bends) An invisible beam (e.g.,
infrared) may also be used if an appropriate detector
is at the destination point to detect the incoming light
A fault locater is a type oftracer that uses a powerful
laser light source that can illuminate through the
fi-ber jacket into the fifi-ber to reveal anomalies such as a
breakinthe lightguide See optical spectrum analyzer,
reflectometer
tracerouteA Unix shell utility written by Van
Jacobson at Lawrence Berkeley Labs which seeks out
and displays the path of a transmission packet as it
travels from host to host, detailing the hops in the
path Traceroute sends an IF datagram to the
desti-nation host, then it iterates through each router,
dec-rementing TTL, discarding the datagram, and
send-ing back ICMP messages until the destination host is
reached Traceroute is extremely useful as a network
diagnostic and optimizing tool and often used in
con-junction with ping See ping The Traceroute Example
inset below shows a sample of traceroute output
showing the IF numbers, hops, and packets
trackballA hardware peripheral device which
re-ceives tactile directional input and transmits it to a
computing device The information transmitted is
similar to that of a mouse or stylus, and is often used
in conjunction with graphical user interfaces (Gills)
Unlike a mouse or stylus, a trackball is generally fixed
in place, with physically separate buttons Trackballs
are common in video arcade games and on laptop
keyboards to increase portability See joystick,
mouse
tracks per inchTPI A measure of the density of a
recording medium such as a phonograph record or formatted hard drive The tracks may be physical (as
in grooves) or virtual (as in a logical segmentation
on a drive that varies according to the file standard and/or operating system)
TRACONTerminal Radar Approach Control.An
airfield navigation radar system designed to aid in landing approaches and takeoffs In commercial air-ports, the TRACON is typically housed in the air traf-fic control tower (ATCT) The Federal Aviation Ad-ministration (FAA) has almost 200 ofthese radar ap-proach facilities in the U.S ATRACON control room may accommodate a number of operators and typi-cally has backup generators to ensure air traffic safety
in the event ofpower outages As cities grow, the need
to support increased and more complex air traffic grows as well To meet this need, the Federal Avia-tion Agency (FAA) has been working on projects to consolidate individual TRACONs into what is termed Large TRACONs
tractor feederA sprocketed paper alignment device used mostly on impact printers It provides more pre-cise control of positioning than most roller feeders
by preventing slippage The tractor feed resembles a pair of short regular series of inverted cleats which fit through corresponding holes in tractor feed paper Tractor feed mechanisms are especially useful for multipage documents (invoices, checks, etc.) on dot matrix printers
trade secretInformation, data, process, or procedure which would lose its commercial value if revealed
to outsiders Nondisclosure agreements (NDAs), policy statements, and inservice training are mecha-nisms which restrict external communication oftrade secrets Iftrade secrets are not specifically identified
by an employer, it may be more difficult to stop or prosecute an offender who has willfully or inadvert-ently revealed them See patent, copyright, nondis-closure agreement, trademark
trademarkA legal designation for the right of an association to the use of a mark in trade It can con-sist of a word, phrase, or symbol sufficiently unique
Traceroute Example
$ traceroute abiogenesis.com
traceroute to abiogenesis.com (207.173.142.184), 30 hops max, 38 byte packets
1 chapman.nas.com (198.182.207.6) 322 me 252 me 251 rna
2 orthanc.nas.com {198.182.207.1} 251 rna 247 rna 275 rna
3 milo-s4.wa.com (204.57.232.1) 277 me 257 rna 296 rna
4 dilbert-fe4-0.wa.com (192.135.191.254) 530 rna 303 rna 273 rna
5 dogbert-f4-0.nwnexus.net (206.63.0.254) 263 me 282 me 286 me
6 borderx2-hssi2-0.Seattle.mci.net (204.70.203.117) 306 me 277 rna 373 me
7 core2-fddi-l.Seattle.mci.net (204.70.203.65) 288 rna 511 rna *
8 bordercore1.Denver.mci.net (166.48.92.1) 299 me 323 me 293 me
9 electric-lightwave.Denver.mci.net (166.48.93.254) 294 me 351 rna 313 rna
10 H3-0.1.scrlib01.eli.net (207.0.56.162) 329 me 394 rna 591 rna
11 gW2-CALWEB-DOM.eli.net (208.131.46.46) 730 ma gwl-CALWEB-DOM.eli:net (208.131.46.30) 507 roB gw2-CALWEB-DOM.eli.net (208.131.46.46) 357 me
12 abiogenesis.com (207.173.142.184) 362 rna 358 me 350 me
Trang 8industry Provided it is not already owned by another
entity, a trademark becomes valid as soon as a
com-pany uses it in trade according to certain stipulations,
provided the company continues using it You
can-notcom~ up with a trademark idea, not use it, and
claim it later ifsomeone else uses it Trademarks may
be registered federally for a fee, although this is not
required The motivation for trademark registration
is to provide prima facie evidence in the event of a
legal dispute Unregistered trademarks must be
iden-tified with a™ symbol, and registered trademarks
must be identified with an® symbol Policing of
trademark violations is not a responsibility ofthe
fed-eral government or of the agency that registers a
trademark; it must be done by the company seeking
to protect the trademark Trade names are similar to
trademarks and are registered at the state level There
can be more than one company using the same trade
name, if the line of business is sufficiently different
to prevent confusion
The Commerce Department's large database ofpatent
text and images, 800,000 trademarks and 300,000
pending registrations dating from the 1800s, has been
gradually uploaded to the Web since 1998 See
copy-right, patent http://www.supot.gov/
Traf-O-DataThe first business partnership of Paul
Allen and William R Gates, founded around 1972,
growing out of the business experiences of the less
formally organized Lakeside Programming Group
Allen and Gates worked together on a variety
ofsoft-ware projects including an automobile traffic flow
system At about the same time, they prototyped an
early microcomputer based upon the recently released
Intel 8008, with the participation of a hardware
de-signer, Paul Gilbert They made some tentative
at-tempts to sell this early machine, but it didn't work
during an early demonstration
At about the time Gates graduated from high school,
Allen encouraged him to join him to start a company
to build and sell computers based upon the Intel 8080
chip set, but Gates wasn't fired up about the idea ofa
hardware company, and his parents were
encourag-ing him to continue his post-secondary education The
majority ofGates and Allen's subsequent efforts were
software-related, most significantly, a BASIC
inter-preter for the Altair, and a disk operating system for
IBM, which resulted in the founding of Microsoft
Corporation The subsequent success ofthe company
was due to sales ofsoftware, primarily operating
sys-tems and business applications, and Apple Computer
became the small business success story in computer
hardware
traffic Atenn often used on large communications
systems to describe communications signals, data,
cells, or packets which comprise the information and
signaling associated with the transmissions The term
is sometimes also used to describe the overall flow
and pattern oftraffic in the context of the system it is
on, as in traffic congestion, traffic flow, traffic
moni-toring, traffic engineering, traffic routing, etc In
te-lephony and various systems that are largely analog
information in the context ofcalls, as in call attempts, call connects, call volume, etc In digital systems, it
is often used in a more specific sense to indicate num-bers ofpackets or cells See leaky bucket
traffic capacity Ameasure of the capability of a system to carry a certain maximum number of calls, cells, frames, or packets, depending on how capac-ity is measured or data carried on that particular sys-tem The maximum capacity may not be a fixed num-ber, as on systems where multiple channels may be aggregated to carry certain broad bandwidth types of information On other systems, where one or two wires can carry one and only one communication, traffic capacity is more likely to be expressed as a set
amount Traffic capacity is used in systems design
and marketing to provide buyers a general guideline
as to the capability of a system For example, a rural phone switching system in a small community may only require a capacity of 20,000 call seconds
(usu-ally expressed in increments of hundredca~lseconds)
per hour during peak calling times, providing a mea-sure of whether a system can meet or exceed those needs See traffic concentration
traffic concentrationAmeasure ofcommunications traffic that indicates how different peak traffic peri-ods are compared to traffic on the whole In telephony, the service day is usually broken down into hours for traffic monitoring to determine high and low traffic periods Traffic concentration is typically expressed
as a ratio of the traffic (number of calls) during the busiest hour to the total traffic during a 24-hour pe-riod This may further be calculated over a period of weekdays, weekends, or 7-day weeks to provide sta-tistical averages
traffic engineeringIn more traditional communica-tions systems, traffic engineering is the estimation and application of the type, quantity, and configuration ofdevices and equipment required to meet the needs
of a predicted number of users of the system being designed Experience, trial and error, probability theory, similar system comparison, and insight are all brought into play in designing a system to meet cur-rent and predicted future needs This system works quite well with traditional telephone switching sys-tems and local area networks
As systems become more complex, however, and dis-tributed digital data systems more prevalent, traffic engineering, once the initial equipment is set in place, becomes an even more esoteric process, with much ofthe configuration and selection carried out by com-puter software, not just through physical connections Virtual networks are now laid over physical networks, resulting in several levels of traffic engineering When these networks are interfaced with a global network like the Internet, then prediction ofthe num-ber ofpotential users becomes more difficult and less important than incorporating flexibility and scala-bility into the system to handle unpredictable traffic loads and activities At this level, traffic engineering becomes a collaborative activity between program-mers and traffic engineers, with careful evaluation of
Trang 9Fiber Optics Illustrated Dictionary
data and message priorities - scheduling and
incor-porating deliberate delays, for example, so some types
oftraffic can be set to transmit during off-peak hours
On data networks, many traffic decisions are now
built into the software on servers, gateways, routers,
and some of the high-end switchers
traffic loadThe sum total of the traffic on a
particu-lar system or portion of a system, such as a specific
trunk, leg, or hop, measured at a particular point in
time, or during a particular specified range of time
traffic monitorA mechanism for keeping track of
traffic on a system On data networks, some of the
software included for system administrators allow the
monitoring of various processes, and typically
dis-play them as sampled or realtime graphical charts
Thus, CPU usage, number ofusers, number
oftrans-missions, level oftraffic, etc can be visually assessed,
and statistics derived from computerized traffic and
analysis can be stored and evaluated to make changes
as needed The results of the monitoring are
some-times directly incorporated into other software on the
system which makes adjustments to priorities, number
of users permitted online at one time, and other
pa-rameters that can be changed to increase or decrease
the traffic to optimize use of the system
Sometimes traffic monitoring is a very simple
mecha-nism One of the simplest and most familiar
applica-tions is on modems, where little blinking lights give
some indication of how much data are traveling
through the modem, and when.Ifa user is
download-ing a large file from a Web site and those lights stop
blinking, it's possible that the connection has been
dropped or there is a glitch in the system In ATM
systems, traffic monitoring is an essential aspect of
preventing network congestions and bottlenecks, and
some cells will be flagged as to their discharge
eligi-bility See cell rate, leaky bucket
Traffic Operator Position SystemTOPS A system
to support telephony operators from a toll switch,
TOPS was developed by Northern Electric (later
Northern Telecom) in the early 1970s, a time when
manual cord-based operator terminals were poised to
be gradually replaced by automatic stored-program
switches The historic TOPS-I utilized an Intel 8008
CPU; the first TOPS office was installed in 1975 in
Alaska As computer technologies improved, TOPS
was upgraded to faster, more versatile processors
traffic overflowA situation where demand exceeds
capacity When overflow occurs, the traffic is either
routed to another trunk or leg, or it is rejected and a
signal sent to the user in the form of a signal (like a
fast busy) or a text message (as a broadcast on a
com-puter system) In some data networks, particular
pack-ets may be discarded if there is traffic overflow, or
they may be routed back to the sender
traffic pathThe physical or virtual pathway taken
from the sender to the receiver This may be fixed, as
in direct wire communications and smaller data
net-works, or it may be flexible, as in switched systems
and many larger data networks On very small
sys-tems, where the setup is known and doesn't often
change, a fixed traffic path may be the fastest and
most practical implementation In dynamic data net-works, the communication may not be quite as fast, but the system has an advantage in that it can toler-ate and adjust to unpredictable changes
A path in a phone system usually passes from the
sub-scriber to a demarcation point, usually ajunction box
between the internal and external wiring, through one
or more switching centers which are connected with pathways called trunks, or sometimes through a
wire-less link during part or all of the transmission In a digital computer network, the data may pass from the
sender through various servers, gateways, switches, and routers; each section in the path is called a hop
or a leg, with the various terminal points generically called nodes A data network transmission may also
be wireless for part or all of the path
traffic policingIn ATM networking, a mechanism which detects and controls cell traffic according to specified parameters See cell rate
traffic recorderA meanstorecord traffic on a speci-fied transmissions channel in order to monitor capac-ity, load, efficiency, etc It mayor may not be paired with software that helps analyze the traffic
traffic reportingIn networks, information on traf-fic flow gathered and organized by external analyz-ing devices or internal monitor agents This informa-tion about packet volume, distribuinforma-tion, collisions, and errors may be reported in the form of tables, ASCII graphs and charts, or images, and is essential for con-figuration, tuning, and troubleshooting
traffic shapingIn ATM networking, a mechanism which shapes or modifies bursty traffic characteris-tics in order to create the desired traffic See cell rate
trainv.To instruct, teach, indoctrinate, or drill Train-ing is an important component ofany computTrain-ing sys-tem that must recognize input beyond point and click
or keyboard instructions In pen computing, hand-writing must be interpreted into commands, and it is usually necessary to train the system, by successive trials and feedback, to recognize an individual's style
of writing Some camcorders have eye-controlled systems which need to be trained to track the direc-tion offocus of the user's eye In voice recognidirec-tion systems, software is trained to recognize an individual's mode of speaking OCR systems can be trained to improve recognition of unfamiliar or un-usual character sets While software training systems are not perfect, they have evolved to the point where they do much useful work, and improvements in tech-nology and software algorithms indicate that some day natural methods of computer input may super-sede keyboard and mouse entry for many applica-tions
trainingAnautomatic feature of some hardware and software systems to evaluate the characteristics of incoming signals (timing, delay, etc.) or information (handwriting, voice, etc.) and improve performance
or recognition through successive adjustments and feedback See artificial intelligence, expert system, robotics
Training, Planning & Operational SupportTPOS
A support function within the Operations Division of
Trang 10coordinates telecommunications operational planning
among NCS elements, provides educational
semi-nars, cooperates with other federal and regional
or-ganizations, and participates in the Regional
Inter-agency Steering Committee (RISC) meetings See
National Communications System
transaction1.Anagreement, or exchange of
infor-mation or goods, between two or more parties or
en-tities 2 A business transaction, which may be
sub-ject to various recording requirements (contracts,
taxation, audit records, etc.) 3.Anentry into a
data-base or spreadsheet
transaction, networkAny ofa number of situations
in which information or signals are exchanged, passed
on, recorded, or evaluated Examples of network
transactions include protocol determinations and
con-versions, security-level evaluation and processing,
routing, transmission between nodes, error
process-ing, etc
Transaction Capability Application PartTCAP In
the SONET specification, there are several chapters
regarding the function, formats, and definitions for
TCAP provided in the ANSI T1.114-1996 document
Transaction TeamA group with the Office of
Gen-eral Counsel that coordinates the FedGen-eral
Communi-cation Commission's (FCC's) review ofappliCommuni-cations
for major transactions and changes The Team was
announced in January 2000 as a response to an
un-precedented number ofsignificant mergers in the
tele-communications industry and was tasked with
streamlining the review process while still
safeguard-ing the public's interests
transaction trackingA system of recording each
instance of a transaction and, sometimes, the actual
transaction or its outcome In database or spreadsheet
applications, for example, each transaction may be
recorded as entered, in order to prevent loss of data
due to a series of transactions not having been saved
at regular intervals This type of live recording of
transactions frees the user from worrying about
"saves" and ensures that, under most fault situations,
no more than the most recent entry may be lost See
ticket
transatlantic cableA communications link across
the Atlantic Ocean incorporating a bundle of wires
or, more recently optical fibers, within a tough,
cor-rosion-resistant insulating protective sleeve The
cable is laid along the ocean bottom in regions and
at depths where the likelihood ofsevering by boat
an-chors is less Maintenance ofoceanic cables is a
com-plicated business, so much emphasis is put on
build-ing and installbuild-ing them correctly in the first place
The invention ofthe telegraphy in the 1800s provided
a strong motivation for laying a cable to bridge the
communication gap between North America and
Eu-rope Since postal messages could take from several
weeks to several months to traverse the Atlantic, there
was a potential goldmine in the provision of cable
services Samuel Morse was one of the more
promi-nent inventors who suggested the feasibility ofa cable
between North America and Europe
of the first commercially practical telegraphs in En-gland and America and the laying of the first work-ing oceanic cable The first attempts did not succeed, however, due to problems with installation, insula-tion, and capacitance over long distances, but im-provements in insulation, and trial and error experi-ence, resulted in eventual success
The first working transatlantic cable was installed in August 1858, initiated by F.N Gisborne's efforts to interlink maritime Canada, and financed and pro-moted by Cyrus W Field A more permanent instal-lation was realized by Field and his associates in July
1866.Anadditional link was established between Ire-land and Canada, in 1894 Cables to other continents and through other oceans followed as the technology improved In the 1870s and 1880s, companies were formed to lay cables to South America and Africa With increasing demands for high-speed wideband communications links for data communications, transatlantic cables are more important than ever; the old wire cables are being replaced by fiber optic cables and new cables are being installed to link re-gions not previously interlinked See British Indian Submarine Telegraph Company; Field, Cyrus West; Gisborne, Frederic Newton; gutta-percha; Pender, John; Submarine Telegraph Company
Historic Transatlantic Cable Telephone Call
Prime Minister Richard Bennett (with cabinet mem-bers) speaking over a transatlantic telephone to George Perley at the British Empire Trade Fair at Buenos Aires, Argentina, in March 1931 [National
Archives ofCanada National Film Board image.]
Transcontinental CableA generic euphemism for the U.S Defense communications system stretching from Washington, D.C to California and Florida dur-ing and after World War II It was called this because
of the labeling of the dig warning signs located in fields and near garden shed-like repeater stations po-sitioned every few miles along the cable routes across the country See L CXR
transceiverDevice which transmits and receives within a single unit, often sharing circuitry to reduce size and weight See transmitter, receiver