电信专业英英词典T-2（在线收听）

　　Terrestrial Microwave Radio

　　Terrestrial microwave radio is a transmission systems consisting of at least two radio transmitter/receivers (transceivers) connected to high gain antennas (directional antennas which concentrate electromagnetic or radiowave energy in narrow beams) focused in pairs on each other. The operation is point-to-point, that is, communications are established between two and only two antennas (installations) with line-of-sight visibility. This can be contrasted to point-to- multipoint systems like broadcast radio or television.

　　TIA

　　Telecommunications Industry Association

　　Time Division Multiplexing (TDM)

　　Time Division Multiplexing is a transmission facility shared in time (rather than frequency), i.e., signals from several sources share a single channel or bus by using the channel or bus in successive time slots. A discrete time slot or interval is assigned to each signal source.

　　Time Division Switch

　　A time division switch is a switch that implements the switch matrix using the TDM process, in a time-slot interchange (TSI) arrangement (usually denoted by T in combined time and space division switches).

　　Token Passing Bus LAN (IEEE 802.4)

　　A token passing bus LAN is a LAN using a deterministic access mechanism and topology in which all stations actively attached to the bus "listen" for a broadcast token or supervisory frame. Stations wishing to transmit must receive the token before doing so; however the next logical station to transmit may not be the next physical station on the bus. Access is controlled by pre- assigned priority algorithms.

　　Token Passing Ring LAN (IEEE 802.5)

　　A token passing ring LAN is a LAN using a deterministic access mechanism and topology, in which a supervisory frame (or token) is passed from station to adjacent station sequentially. Stations wishing to transmit must wait for the "free" token to arrive before transmitting data. In a token ring LAN the start and end points of the medium are physically connected, leading to a ring topology.

　　TP

　　transaction processing

　　Tracking

　　Tracking features user-defined approval levels and project milestone tables to generate project cost and status information, which is tracked for reporting and review. As assigned tasks are completed, supervisors make daily entries identifying the number of hours worked on a task, materials used, and the number of work units completed. This information is then available for project jeopardy tracking, cost tracking, and determination of contractor payments due.

　　Traffic

　　Traffic is the flow of information within a telecommunications network.

　　Transceiver

　　A transceiver is a generic term describing a device that can both transmit and receive. In IEEE 802 local area network (LAN) standards, a transceiver consists of a transmitter, receiver, power converter, and, for CSMA/CD LANs, collision detector and jabber detector capabilities. The transmitter receives signals from an attached terminal's network interface card (NIC) and transmits them to the coaxial cable or other LAN medium. The receiver receives signals from the medium and transmits them via the transceiver cable and NIC to the attached terminal. The jabber detector is a timer circuit that protects the LAN from a continuously transmitting terminal.

　　Transfer Mode

　　Transfer mode is a generic term for switching and multiplexing aspects of broadband integrated services digital networks (BISDN), adopted by CCITT Study Group XVIII.

　　Transmission control protocol/internet protocol (TCP/IP)

　　See "Internet suite of protocols" and "TCP/IP".