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T1 - T1 is a 1.544 Mbps multichannel digital transmission
system for voice or data provided by long distance carriers.
Also referred to as DS1 (Data Services).
T3 - T3 is a 44.736 Mbps multichannel digital transmission
system for voice or data provided by long distance carriers.
Also referred to as DS3 (Data Services).
Tap - On Ethernet 10Base5 thick coaxial cable, a tap
is a method of connecting a transceiver to the cable by drilling
a hole in the cable, inserting a contact to the center conductor,
and clamping the transceiver onto the cable at the tap.
TC - Telecommunications Cross Connect.
TDR - See Time Domain Reflectometry
Teflon - Dupont Company trademark for flourocarbon resins
(see FEP and TFE).
Telecommunications Closet - see Closet
Telecommunications Equipment Room - see Equipment Room
Terminal - A point at which information may enter or
leave a communications network or a device by means of which
wires may be connected to each other.
Terminator - A device that provides electrical resistance
at the end of a transmission line. Its function is to absorb
signals on the line, thereby keeping them from bouncing back
and being received again by the network.
TFE - Tetraflouroethylene. A thermoplastic material with
good electrical insulating properties and chemical and heat
resistance.
Thermal Rating - The temperature range in which a material
will perform its function without undue degradation.
Thermoplastic - A material which will soften, flow, or
distort appreciably when subjected to sufficient heat and pressure.
Examples are polyvinyl chloride and polyethylene.
Thermosetting - A material which will not soften, flow,
or distort appreciably when subjected to sufficient head and
pressure. Examples are rubber and neoprene.
Thicknet - Ethernet 10Base5 coaxial cable.
Thinnet - Ethernet 10Base2 coaxial cable. Also called
"cheapernet".
TIA - Telecommunications Industry Association. Body which
authored the TIA/EIA 568-A "Commercial Building Telecommunications
Wiring Standard" in conjunction with EIA.
Time Division Multiplexing (TDM) - A technique for combining
many signals on a single circuit by interleaving bits or bytes
of data from successive channels.
Time Domain Reflectometry - A technique for measuring
cable lengths by timing the period between a test pulse and
the reflection of the pulse from an impedance discontinuity
on the cable. The returned waveform reveals many undesired cable
conditions, including shorts, opens, and transmission anomalies
due to excessive bends or crushing. The length to any anomaly,
including the unterminated cable end, may be computed from the
relative time of the wave return and nominal velocity of propagation
of the pulse through the cable. See also Optical Time Domain
Reflectometry.
Tinsel - A type of electrical conductor comprised of
a number of tiny threads, each having a fine, flat ribbon of
copper or other metal closely spiraled about it. Used for small
size cables requiring limpness and extra-long flex life.
Tip - A polarity designation of one wire of a pair indicating
that the wire is that of the primary (common) color of a 5-pair
group (e.g. the white-blue wire of the blue pair) or a wiring
contact to which the tip wire is connected or the positive wiring
polarity (also see "ring").
TNC - A threaded connector used to terminate coaxial
cables. TNC is an acronym for threaded Neill-Concelman.
Token Passing - A network access method in which a station
must wait to receive a special token frame before transmitting.
Token-Ring - A local area network (LAN) protocol defined
in the IEEE 802.5 standard in which computers access the network
through a token passing scheme. Uses a star-wired ring topology.
Topology - The physical or logical interconnection pattern
of a network.
Transceiver - A combination of the words TRANSmitter
and reCEIVER. A transceiver is the set of electronics that send
and receive signals on the Ethernet media system. Transceivers
may be small outboard devices, or may be built into an Ethernet
port. Also called Media Attachment Unit, or MAU.
Tracer - The contrasting color coding stripe along an
insulated conductor of a wire pair.
Transducer - A device for converting mechanical energy
into electrical energy.
Transfer Impedance - For a specified cable length, transfer
impedance relates to a current on one surface of a shield to
the voltage drop generated by this current on the opposite surface
of the shield. Transfer impedance is used to determine shield
effectiveness against both ingress and egress of interfering
signals. Shields with lower transfer impedance are more effective
than shields with higher transfer impedance.
Transmission Line - An arrangement of two or more conductors
or a wave guide used to transfer a signal from one location
to another.
Transmission Media - Anything such as wire, coaxial cable,
fibre optics, air or vacuum, that is used to carry a signal.
Transmitter - A device that converts electrical signals
for transmission to a distant point. In fibre optic systems,
the electronic component that converts electrical energy to
light energy.
Transition Point - A location in the horizontal cabling
where flat undercarpet cable connects to round cable.
Tree Topology - LAN topology similar to linear bus topology,
except that tree networks can contain branches with multiple
nodes.
Triaxial Cable, Triax - Triax cable is coax cable with
an additional outer copper braid insulated from signal carrying
conductors. It has a core conductor and two concentric conductive
shields.
Triboelectric Noise - Noise generated in a shielded cable
due to variations in capacitance between the shield and conductor
as the cable is flexed.
Trunk Cable - see Feeder Cable.
TSB - Telecommunications Systems Bulletin
Turn-key - A contractual arrangement in which one party
designs and installs a system and "turns over the keys"
to another party who will operate the system.
Twinaxial Cable, Twinax - A type of communication transmission
cable consisting of two center conductors surrounded by an insulating
spacer which in turn is surrounded by a tubular outer conductor
(usually a braid, foil or both). The entire assembly is then
covered with an insulating and protective outer layer. It is
similar to coaxial cable except that there are two conductors
at the center.
Twin-lead - A transmission line having two parallel conductors
separated by insulating material. Line impedance is determined
by the diameter and spacing of the conductors and the insulating
material and is usually 300 ohms for television receiving antennas.
Twisted Pair - A multiple conductor cable whose component
wires are paired together, twisted, and enclosed in a single
jacket. Each pair consists of two insulated copper wires twisted
together. When driven as a balanced line, the twisting reduces
the susceptibility to external interference and the radiation
of signal energy. Most twisted-pair cabling contains either
2, 4, or 25 pairs of wires.
Tx - Transmit
Type N Connector - A threaded barrel constant impedance
coaxial connector for large diameter cable such as Ethernet
10Base5 thicknet cable.
Type 1 - 150 ohm shielded twisted pair (STP) cabling
conforming to the IBM Cabling System Specifications. Two twisted
pairs of 22 AWG solid conductors for data communications are
enclosed in a braided shield covered with a sheath. Tested for
operation up to 16 MHz. Available in plenum, non-plenum, riser,
and outdoor versions.
Type 1A - Enhanced version of IBM Type 1 cable rated
for operation up to 300 Mhz. Meets electrical specifications
for 150 ohm STP-A Cable as documented in the TIA/EIA 568-A standard.
Type 2 - 150 ohm shielded twisted pair (STP) cabling
conforming to the IBM Cabling System specifications. Two twisted
pairs of 22 AWG solid conductors for data communications are
enclosed in a braided shield. Four additional pairs of 22 AWG
solid conductors for telephones are also included in the cable
jacket but outside the braided shield. Tested for operation
up to 16 MHz. Available in plenum and non-plenum versions.
Type 2A - Enhanced version of IBM Type 2 cable rated
for operation up to 300 Mhz. Meets electrical specifications
for 150 ohm STP-A Cable as documented in the TIA/EIA 568-A standard.
Type 3 - IBM Cabling System designation for 100 ohm unshielded
twisted pair (UTP) cabling similar to TIA/EIA Category 3 cabling.
22 AWG or 24 AWG conductors with a minimum of two twists per
linear foot. Typically four twisted pairs enclosed within cable
jacket.
Type 5 - 100/140 micron optical fibre cable conforming
to the IBM Cabling System specifications. Two optical fibres
are surrounded by strength members and a polyurethane jacket.
Type 5J is a 50/125 micron version defined for use in Japan.
Type 6 - 150 ohm shielded twisted pair (STP) cabling
conforming to the IBM Cabling System specifications. Two twisted
pairs of 26 AWG stranded conductors for data communications.
Flexible for use in making patch cables. Tested for operation
up to 16 MHz. Available in non-plenum version only.
Type 6A - Enhanced version of IBM Type 6 cable rated
for operation up to 300 Mhz. Meets electrical specifications
for 150 ohm STP-A Cable as documented in the TIA/EIA 568-A standard.
Type 8 - 150 ohm under-carpet cable conforming to the
IBM Cabling System Specifications. Two individually shielded
parallel pairs of 26 AWG solid conductors for data communications.
The cable includes "ramped wings" to minimize visibility
when installed under carpeting. Tested for operation up to 16
MHz.
Type 9 - 150 ohm shielded twisted pair (STP) cabling
conforming to the IBM Cabling System Specifications. A plenum
rated cable with two twisted pairs of 26 AWG solid or stranded
conductors for data communications enclosed in a braided shield
covered with a sheath. Tested for operation up to 16 MHz.
Type 9A - Enhanced version of IBM Type 9 cable rated
for operation up to 300 Mhz. Meets electrical specifications
for 150 ohm STP-A Cable as documented in the TIA/EIA 568-A standard. |
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