| T: Abbreviation for
tera. One trillion or 1012. |
| T1: In telecommunications, the cable used to transport
DS1 service. |
| Tap Loss: In a fiber optic coupler,
the ratio of power at the tap port to the power at the input port. |
 |
| Tap Port: In a coupler where the splitting
ratio between output ports is not equal, the output port containing
the lesser power. |
| T-Carrier: Generic
designator for any of several digitally multiplexed telecommunications
carrier systems. |
| TCP/IP: Abbreviation for transmission control
protocol/Internet protocol. Two interrelated protocols that are part of
the Internet protocol suite. TCP operates on the OSI transport layer and breaks data
into packets. IP operates on the OSI network layer and routes packets.
Originally developed by the U.S. Department of Defense. |
| TDM: See time-division
multiplexing. |
| TDMA: See time-division
multiple access. |
| TEC: Abbreviation for
thermoelectric cooler. A device used to dissipate heat in electronic
assemblies. |
 |
| Tee Coupler: A three-port optical coupler. |
 |
| Telecommunications
Management Network (TMN): A network that interfaces with a telecommunications network at several points in
order to receive information from, and to control the operation of, the
telecommunications network. |
| Ternary: A
semiconductor compound made of three elements (e.g., GaAlAs). |
| Thermal Noise: Noise
resulting from thermally induced random fluctuation in current in the receiver’s load resistance. |
| Throughput Loss: In a
fiber optic coupler,
the ratio of power at the throughput port to the power at the input
port. |
| Throughput Port: In a coupler where the splitting
ratio between output ports is not equal, the output port containing
the greater power. |
| TICL: Abbreviation for temperature induced cable loss. Optical loss as a result
of extreme temperatures outside a fiber
optic cable’s environmental specifications. |
| Tight-Buffer: A material tightly
surrounding a fiber in a cable,
holding it rigidly in place. |
 |
| Time-division Multiplexing (TDM): A transmission technique whereby several low-speed channels are
multiplexed into a high-speed channel for transmission. Each low-speed
channel is allocated a specific position based on time. |
 |
| Time-division
Multiple Access (TDMA): A communications technique that uses
a common channel (multipoint or broadcast) for communications among multiple users by
allocating unique time slots to each user. Used extensively in satellite
systems, local
area networks, physical security systems, and combat-net
radiosystems. |
| TMN: See telecommunications
management network. |
| Token Ring: A ring-based
network scheme in which a token is used to control access to a network.
Used by IEEE 802.5 and FDDI. |
| Total Internal
Reflection: The reflection that occurs when light strikes an
interface at an angle of incidence (with respect to the normal) greater
than the critical
angle. |
| Transceiver: A device that performs, within one chassis, both
telecommunication transmitting and receiving functions. |
| Transducer: A device that converts energy from one form to another, such as
optical energy to electrical energy. |
| Transmitter: A
device that includes a source and driving electronics. It functions as an electrical-to-optical
converter. |
 |
| Transponder: The
part of a satellite that receives and transmits a signal. |
| Tree: In
communications networks, a physical topology consisting of a hierarchy of
master-slave connections between a concentrator and other FDDI nodes (including subordinate concentrators). |
| Trunk: 1) In a communications
network, a single transmission channel between two switching centers or
nodes, or both. 2) A circuit between switchboards or other switching
equipment, as distinguished from circuits which extend between central
office switching equipment and information origination/termination
equipment. Trunks may be used to interconnect switches, such as major,
minor, public and private switches, to form networks. |
| TTL: Abbreviation
for transistor-transistor logic. An old logic
family. |
| Twisted Pair (TP) Cable: A cable made up of one or more separately insulated twisted wire pairs, none of
which is arranged with another to form quads. |
