"A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M",
"N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"

TERMINATION: The load connected to a transmission line, circuit, or device.

THRESHOLD: The minimum value of a signal that can be detected by the system or sensor.

THROUGHPUT: The number of bits, characters, or blocks passing through a data communication system, or portion of that system.

Time Constant: Time required for an exponential quantity to change by an amount equal to 63.2 percent of the total change that can occur. [Time Constant Graph]. The interval required for a system or circuit to change a specified fraction from one state or condition to another.

Time-Division Multiplexing (TDM): Digital multiplexing in which two or more apparently simultaneous channels are derived from a given frequency spectrum, i.e., bit stream, by interleaving pulses representing bits from different channels. Note: Successive pulses represent bits from successive channels, e.g., voice channels in a T1 system.

TOKEN: In certain local-area-network protocols, a group of bits that serves as a symbol of authority, is passed among data stations, and is used to indicate the station that is temporarily in control of the transmission.

TOLERANCE. The maximum permissible error or variation from the standard in a measuring instrument. A maximum electrical or mechanical variation of specifications that can be tolerated without impairing the operation of a device. Resistor Tolerance

Transformer. A device composed of two or more coils, linked by magnetic lines of force, used to transfer energy from one circuit to another. Manufacturers of Transformers



TRANSITION. The time it takes to shift from a mark to a space condition or from a space to a mark condition.

Transmission block: A group of bits or characters transmitted as a unit and usually containing an encoding procedure for error control purposes. In data transmission, a group of records sent, processed, or recorded as a unit. Note: A transmission block is usually terminated by an end-of-block character (EOB), end-of-transmission-block character (ETB), or end-of-text character (EOT or ETX).

TRANSMISSION FRAME. A data structure, beginning and ending with delimiters, that consists of fields predetermined by a protocol for the transmission of user data and control data.

TRANSMISSION LINE. A device designed to guide electrical or electromagnetic energy from one point to another. The material medium or structure that forms all or part of a path from one place to another for directing the transmission of energy, such as electric currents, magnetic fields, acoustic waves, or electromagnetic waves.

TRANSMISSION LOSS. The decrease in power that occurs during transmission from one point to another.

TWIN CABLE. A cable composed of two parallel conductors separated from each other by a ribbon-like insulator or encased by a foam insulator. [Twin-Lead]

TWISTED PAIR. A line consisting of two insulated wires twisted together to form a flexible line without the use of spacers.