Dictionary of Technical Terms - U

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U

U

One of the two color difference signals that modulate subcarrier in the PAL system. U corresponds to weighted B-Y, and V corresponds to weighted R-Y. The formula for deriving the U signal is .493(B-Y).

UART

Universal asynchronous receiver/transmitter. An integrated circuit that interfaces a microprocessor to a serial I/O port.

unbalanced

Frequently, a circuit having one side grounded. A circuit, the two sides of which are electrically different. See also single-ended and balanced.

unconditional

In telecommunications, used with the MML switch commands. An unconditional command is implemented irrespective of previous connections made.

underscan

A video monitor condition in which the raster does not expand completely to the physical edges of the CRT screen, resulting in a black border around the edges of the screen. Some monitors can be set to underscan mode.

unit interval

In telecommunications, the time duration for one bit period at a specified data transmission rate. The basic unit for measuring jitter.

unity gain

An amplifier or active circuit in which the output amplitude is the same as the input amplitude.

unity key frame

In digital picture manipulators, a part of memory used to retain user-defined values for parameters such as background color, border ON/OFF, key frame duration, etc.

unity picture

In digital picture manipulators, a picture in which all of the key frame parameters that define the picture are at their default values.

unity source memory

In digital picture manipulators, memory used to retain user-defined settings of source-related parameters for each source, similar to unity key frame.

unterminated

Not terminated.

uplink

The earth station that transmits signals to a satellite for relay to another location on the ground.

upstream

1. Placed ahead of other devices in a video signal path. 2. Describes the location of keyers in a mix/effects level or in the overall switcher architecture. 3. Relates to the priority of the video signals as they are combined through the video production switcher.
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