Grass Valley Dictionary Grass Valley Dictionary

Dictionary of Technical Terms - T

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 Num



In telecommunications, the paired cable used to transport DS1 service.


Test access port. In telecommunications, an MML command that allows any port on a digital switch to be used as a test port.


1. Direct, immediate switching from one source to another, occurring during the vertical interval for clean transitions. 2. The control panel operation which brings a preset source or sources to air.


1. A lamp which lights to indicate that the associated video source is in use. Typical locations of tally lamps are on the front of video cameras and in the crosspoint pushbuttons of video switchers. 2. The acknowledgment returned to the control panel or terminal that an operation has been executed.

tally relay

A relay whose contacts close when an associated function is placed on-air. Tally relays are used in video switchers to provide the customer a way to light a camera tally lamp when the camera is placed on air at the switcher panel.

target space

In digital picture manipulators, the axes of the monitor screen.


Time base corrector.


Tension, continuity & bias.


Temperature compensated crystal oscillator.


Technical director. Switcher operator.


Time division multiplex. The management of multiple signals on one channel by alternately sending portions of each signal and assigning each portion to particular blocks of time.


A lateral displacement of the video lines due to sync instability. Visually it appears as though parts of the images have been torn away.

technical director

The operator of the video production switcher in a live broadcast.


A device for capturing movie film as a video signal.


Electronically-linked meeting conducted among groups in separate geographic locations.


Text shown on a television monitor to assist a performer or speaker.

temporal aliasing

A defect in a video picture that occurs when the image being sampled moves too fast for the sampling rate. A common example occurs when the rapidly rotating spokes of a wagon's wheels appear to rotate backwards because of video scanning that moves more slowly than the spokes.


A Grass Valley 10 x 1 compact video/audio routing switcher.


A Grass Valley Group one rack unit router with 10 inputs and 20 outputs.

tension, continuity & bias

In key frame effects, the controls for moving an object along a path. Tension controls the length of the tension vector, continuity controls the angle of the path, and bias controls whether the path will be "pulled" towards the previous or the following key frame.

terminal block

An insulating base equipped with one or more terminal connectors.

terminal equipment

Equipment at an end of communication lines that send and/or receive certain signals for specific services. Some examples in television include sync pulse generators, processing amplifiers, and distribution amplifiers.

terminate, termination

To complete a circuit by connecting a resistive load to it. A video termination is typically a male BNC connector which contains a 75 ohm resistive load. When there are looping inputs, any unused looping input must be terminated in 75 ohms to ensure proper signal levels and to minimize reflections.


A transmission line ending in a resistance equal to the characteristic impedance of the line so that there are no reflections or standing waves.

test point

Typically a post in a circuit that can be monitored to test a parameter of the circuit.

test signal

An electronic signal with standard characteristics used to test the capability of circuits.

test signal generator

Device that generates special television signals used for aligning television equipment.

texture mapping

The ability of a digital picture manipulator to create textured surfaces that can be applied to shapes.


See total harmonic distortion.


A film pattern made by applying conductive and insulating materials to a ceramic substrate by a silk-screen process. Thick films can be used to form conductors, resistors, and capacitors.

threshold current

In telecommunications, the minimum forward current for which the laser is in a lasing state at a specified temperature.


A measure of efficiency of a system; the rate at which the system can handle work.

tie line

A link from the output of one routing matrix to the input of another matrix.

time base corrector

Device used to correct for time base errors and stabilize the timing of the video output from a tape machine.

time base error

Horizontal rate flutter of a video signal caused by tape stretch and inherent imperfections in the tape transport mechanism of a videotape recorder.

time code

Timing code laid down on video-tape to give each frame a unique number so as to ensure exact transitions during editing.

time delay

The time required for a signal to travel through a circuit.


The devices or signals in question are synchronized with one another.


1. An effects control feature that enables the operator of a switcher or digital picture manipulator to preprogram a series of timed events, such as auto transitions, E-MEM recalls, and GPI triggers, and then replay them. 2. A window within a video editing application where clips and other production elements can be graphically arranged to create a fully edited production. The horizontal axis of the timeline window represents a timeline of the show.


In the case of ITU-R BT.601-2 (CCIR-601), a technique for transmitting three signals at the same time on a group of parallel wires (parallel cable).

timing pulse

See sync pulse.

timing scatter

Routing switcher term describing varying electrical lengths.


A caption.

title inserter

See title key.

title key

A key effect which imposes a caption over a background scene. The source of the title key signal may be a character generator or a graphics camera.


To change back and forth between two states (for instance: on, off, on, off, etc.) by alternately opening and closing an electric circuit.


Typically refers to a single-frequency audio signal used as a level setting reference.

total harmonic distortion (THD)

The ratio of the sum of the ampli-tudes of all signals harmonically re-lated to the fundamental and the amplitude of the fundamental signal.


A sine-squared pulse used as an indication of frequency and phase response.

T-pulse to bar

A specification term relating to frequency response of video equipment. A video signal containing equal amplitude T-pulse and bar portions is passed through the equipment and the relative amplitudes of the T-pulse and bar are measured at the output. A loss of response is indicated when one portion of the signal is lower in amplitude than the other.


In telecommunications, an MML command to trace designated ports.


A GVG trademarked editor program that reads the EDLs from several generations of edits to a show and constructs a final EDL with references back to the original source back to the original source show will be recorded from the original source material, ensuring against multigenerational degradation.


1. The section of a videotape where a particular signal is recorded. There are separate tracks for video, audio, time code, etc. 2. Levels in the timeline window of an editing application where video and audio elements can be placed to insert them into the production.


A digital picture manipulator effect in which an image repeats on screen as it moves so that it appears to leave a trail of duplicate images behind it. If the trail is set to decay mode, the trailing images gradually fade away.

trailing edge

The transition of a pulse that occurs last, such as the high-to-low transition of a high clock pulse.


A device that converts one form of encoded video to another, e.g., to convert NTSC video to PAL. Sometimes mistakenly used to mean translator.


A device that converts one form of energy into another. For example, in fiber optics, a device that converts light signals into electrical signals.

transform, transformation

In digital picture manipulators, to digitally change a picture in some way that alters the appearance or location of the picture, such as applying translation, rotation, perspective changes, size changes, aspect and skew manipulations, etc.

transformation path

In digital picture manipulators, the path or direction and speed that a transformed image follows as it moves from one key frame to the next.


An electrical device that inductively transfers electrical energy from one circuit to another circuit at the same frequency but usually at a different impedance, voltage, and current.


A momentary surge on a signal or power line.


A semiconductor electronic device having three electrodes and used for signal buffering, amplification, etc.


A change from one picture to another. A transition can be a wipe, mix, or cut.

transition interrupt

Selection of a new preset source with a transition in progress. The switcher removes the old program video in time and remains (if necessary) in black/silent until a newly selected source is ready and placed on-air.

transition status display

A patented GVG device that keys MASTER-21 status into an external television monitor.


1. In digital picture manipulators, movement of the image or screen along its X,Y, or Z axis. 2. Changing a video signal from one format to another.


A device used to convert from one component set to another, e.g., to convert Y, R-Y, B-Y signals to RGB signals.


Equipment used to generate and amplify an RF carrier signal, modulate this carrier with information, and radiate the modulated RF carrier into space.

tray (frame)

The metal cabinet that holds circuit boards.


A special form of coaxial cable containing three conductors.


A pulse that starts an action or function.


1. To make a fine adjustment in a circuit or a circuit element. 2. In video editing systems, to add or subtract time code to adjust edit points.


Brand of connector. Also a brand of tool for plugging and unplugging BNC connectors.


Also called cable trough. A slot underneath the flooring of a television facility where cables are laid for running from room to room.


Timing reference signals in composite digital systems (four words long).


Timing reference signal identifica-tion. A four-word reference signal used to maintain timing in composite digital systems.


Deletion of lower significant bits on a digital system. Usually results in digital noise.


A telephone circuit.


A transformation in which the picture appears to turn around its X (horizontal) axis. See also flip.

tuned-circuit equalizer

A circuit that is adjusted to be resonant at a particular frequency. Equalizer that employs circuits consisting of inductance and capacitance that can be adjusted for resonance at the desired frequency.

twisted pair

A cable composed of two small insulated conductors twisted together. Since both wires have nearly equal exposure to any interference, the differential noise is slight.


Teletypewriter exchange service.


A GVG broadcast quality character generator running under Windows NT on the DEC Alpha workstation.
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