U : A term used to define the unit of height in a rack-mounted assembly. A one-U device is 13/4" high (44mm). A two-U device is twice as tall, etc.

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U-Matic : A video tape recorder format developed by Sony for professional use. A 3/4" helical scan video cassette, it has become the world standard for industrial and semi-pro videotape productions. This machine is also used in conjunction with a Sony PCM 1610 or PCM 1630 encoder to record digital audio instead of video."

 

UART : Universal Asynchronous Receiver Transmitter. An integrated circuit that carries out the function of asynchronous, bi-directional communication between a microprocessor and a serial interface. In MIDI, it is a part of the interface that forms the link between the processor and the MIDI sockets.

UDF Universal Disk Format: for use with optical medium and avoids the problems and confusion that CDROMs had because of the many different file formats used. Permits the use of a DVD by DOS, OS/2, Macintosh, windows, and UNIX operating systems, as well as dedicated players.

 

UHF : Ultra High Frequency. The band of television broadcast frequencies reserved by the FCC for local and community-access stations, local weather services, stock reports, etc.; channels 14 and higher. Compare with VHF.

 

Ultra ATA : See IDE.

 

Ultra-Stereo : See stereo optical print.

 

ultrasonic : Having frequencies above the normal range of human hearing, i.e., higher than about 20kHz.

 

una corda : One string. Used in piano music to indicate the use of the soft pedal. See tre corda.

 

unadvertised specials : In film, sounds that appear on a track, but whose presence is not noted on the cue sheet.

 

unbalanced lines : Any transmission line in which the two conductors are at different potentials with respect to ground. In an unbalanced connection, the ground conductor does double-duty, completing the electrical circuit and serving as a shield. Compare with balanced line.

 

undermodulation : A situation which occurs when the amplitude of a signal falls well below the optimum level in a recording or broadcasting system, causing it to be masked by noise. In digital systems, undermodulation can lead to distortion. See overmodulation.

 

underscore : Music that provides atmospheric or emotional background to the primary dialog or narration onscreen to emphasize the action.

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unidirectional microphone : Any microphone in which the pick-up pattern exhibits more sensitivity to sounds approaching on-axis, i.e., any variation of the cardioid pattern. Such as a supercardioid or hypercardioid. See also directional microphone, omnidirectional microphone, polar pattern.

 

Unilink : Sony bi-directional 8-pin bus connector for centralized multi-media control from one master unit.

 

unison : Two notes, or musical lines, which have the same pitch. Also used less precisely to include a musical line played or sung in octaves.

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unit : A single reel of edited mag film, corresponding to a given picture reel. The unit can be either single-stripe or fullcoat, and will usually contain fill leader in order to maintain sync with the picture reel.

 

unity gain : A device which neither attenuates nor amplifies a signal. Most signal processing devices have unity gain, which means that they neither amplify sound nor cause insertion loss, and therefore can be added into an audio system at various places without upsetting the overall gain of the system.

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Universal System Exclusive : A part of System-Exclusive which is intended for all equipment, irrespective of manufacturer. The message uses one of three particular ID numbers after the SOX status byte: 125 is for non-commercial or academic use; 126 is for non-real-time use and includes messages for MTC Set-Up, SDS, MIDI File Dump, Bulk Tuning, and GM; 127 is for real-time use and includes MTC Full Message, User Bits, Show Control, Notation, Device Control, Machine Control, Single-Note Retuning messages, Master Balance, Master Volume, and Real-Time MTC Cueing.

 

Unregistered Parameter Number : See Registered Parameter Number.

 

upbeat : See beat.

 

update mode : In console automation, the operating mode in which previously written automation data is read back to its respective input faders for alteration by the engineer. The position of each fader at the beginning of an update take is defined by the system as its null-point. If the engineer leaves these faders at their initial levels throughout the take, no data will be changed. Any fader movement above or below a null point is read in dBindB, and that track’s data changed to reflect the same dBsamedB change from the previously written signal level. This updated data is then stored for later use.

 

USB : Universal Serial Bus. The new slow-peripheral (i.e., keyboard, mouse) interface technology from Apple Computer.

user bits : (1) A group of 32 bits within the 80-bit SMPTE timecodetimecode message which is available to users for their own purposes, such as recording tape identity numbers, dates, etc.

(2) Also, a System-Exclusive message of the real-time type which implements the SMPTE timecodetimecode message described in user bits.

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UV-22 : See dither.