Imagine Videotek LLM-1770, Инструкция по установке и эксплуатации

Страница: 95 / 122

LLM-1770
Installation and Operation Manual
89
Field. A picture or picture portion which is produced within one cycle of vertical
synchronization. In interlaced systems, a full picture or frame requires two consecutive
fields.
FM Trap. A circuit designed to minimize potential interference from strong FM signals in
receiving equipment, such as a TV demodulator. For example, an FM trap can attenuate
signals between 88-108 MHz to reduce interference on NTSC television channel 6.
Frame. A single full resolution picture as viewed in either a video or film system. In the case
of interlaced video, two consecutive fields provide all of the information of one frame. In
non-interlaced systems, one cycle of vertical synchronization produces a frame. A 60 Hz
interlaced system, produces 30 frames of video in one second. A 60 Hz progressive (or
non-interlaced) system, produces 60 frames of video in one second. Common frame rates
are 24 (film) 25, 29.97, 30, 50, 59.94 and 60.
Frame Synchronizer. An electronic device that synchronizes two or more video signals.
Using one input as a reference, it locks a second signal to the reference.
Frame Store. An electronic method of capturing and storing a single frame of video.
Gamma. This term applies to the linearity of the change from black to white. Gamma
controls adjust the gray or 50% point of the video either up or down, with the effect of
changing the gray level of the video.
Gamut. The whole or total of whatever is being addressed. In color space, gamut refers to
all colors which are included in a particularly defined color group, such as 601 gamut.
Genlock (Generator Lock). A method of synchronization involving the generation of a
video signal that is time and phase locked with another signal.
GPI. General Purpose Interface
Headend. In a cable TV system, the facilities where program sources (satellite, terrestrial,
VTR, local) are received and remodulated for distribution through a cable plant.
High Definition Television (HDTV). High definition television has a resolution of
approximately twice that of conventional television in both the horizontal (H) and vertical
(V) dimensions and a picture aspect ratio (H to V) of 16:9.
High Level. A range of allowed picture parameters defined by the MPEG-2 video coding
specification which corresponds to high definition television.
HRC. Harmonically-Related Carrier
Hue. Color tint
ICPM. Incidental Carrier Phase Modulation. A measurement of picture carrier phase
distortion (affected by the video signal level) that occurs in the transmitter.
Installation Categories. Categories of measurements that occur on circuits attached or
not attached to a live electrical supply outlet. Installation Categories are as follows:

Category I is for measurements that occur on circuits not attached to a live electrical
supply outlet (115/230 VAC). The voltages come from secondary power sources. The
secondary power source includes circuits energized by low-voltage sources and
electronics such as batteries.