VBI

Vertical-Blanking Interval (Of TV signal), U.S. terminology. Otherwise known as field Suppression.

VDU

Visual/Display Unit. TV-type monitor used as a computer display.

Vertical Sync Pulse

A series of pulses which occur during the vertical blanking interval to synchronize the scanning process at the television with that created at the studio. See also Serrated Vertical Pulse.

Vertical Blanking Pulse

A pulse used during the vertical retrace period at the end of each scanning field to extinguish illumination from the electron beam.

VHF

Abbreviation for very high frequency, 30 to 300 Mhz.

VHRR

Very High Resolution Radiometer.

Video Signal

That portion of the transmitted television signal containing the picture information.

Video Pair Cable

A transmission cable containing low-loss pairs with an impedance of 125 ohms. Used for TV pick ups, closed circuit TV, telephone carrier circuit, etc.

Video Monitor

A television that accepts unmodulated baseband signals to reproduce a broadcast.

Videotex

An electronic textual information distribution system, from a central computer to remote VDUS. (Also See Teletext, Viewdata).

Viewdata

Interactive videotex.

VITS

Vertical-interval Test Signal (US); Vision Insertion Test Signal (Europe). See ITs.

Velocity of Propagation

The speed of an electrical signal down a length of cable compared to speed in free space expressed as a percent. It is the reciprocal of the square root of the dielectric constant of the cable insulation.

Volt

A unit of electromotive force.

Voltage Rating

The highest voltage that may be continuously applied to a wire in conformance with standards or specifications.

Voltage Tuned Oscillator (VTO)

An electronic circuit whose output oscillator frequency is adjusted by voltage. Used in downconverters and satellite receivers to select from among transponders.

VSWR (Voltage Standing Wave Ratio)

The ratio between the minimum and maximum voltage on atransmission line. An ideal VSWR is 1.0. Ghosting can result as the VSWR increases. It is also a measure of the percentage of reflected power to the total power impinging upon a device.

VTO

Voltage Tuned Oscillator.

VW-1

A flammability rating established by Underwriters Laboratories for wires and cables that pass a specially designed vertical flame test, formerly designated FR-1.