Varifocal
lens:
is a type of manual zoom lens with a small
zoom ratio (ranging between 4mm to 12mm depending on
brand). It is used when the focal length of the lens
needs to be fine tuned to meet the requirements of the
actual scene. Video
head:
is an internal part of a VCR which rotates
very rapidly and writes the video signal on to the
video tape during recording while reading the video
signal from the tape during playback.
Vertical
resolution:
is the number of horizontal lines which can
be resolved in a picture. It is limited by the television
scanning method - NTSC, PAL etc.
Vertical
shift register:
is a part of the interline transfer CCD chip
and is placed in between every column of pixels. At
the end of each frame the charge from the pixels are
sent to the vertical shift register (VSR) and then
row by row to the horizontal shift register.
Vertical
streaking:
is a type of picture distortion that occurs
due to overloading of the pixels in an interline transfer
chip. It appears as vertical streaks above and below
the bright part of the picture.
VHS
Victor Home System:
is a type of popular recording format used
in video cassette recorders. The other type of formats
are betamax, 8mm, system 2000 and U-matix (professional).
Vibration
sensor:
is a type of device which can be activated
by vibrations in a pre determined zone and can be
interfaced with a switcher to switch the nominated
camera for extended viewing.
Video
amplifier:
is a type of amplifier used to boost the
strength of a video signal.
Video
cassette recorder:
is a device which can record (or playback)
video and audio signals on a magnetic tape housed
in a cassette.
Video
distribution amplifier:
is a type of amplifier used not only to boost
the strength but also create multiple outputs of the
video signal.
Video
intercom:
is a door entry system which uses both audio
and video to communicate and/or control movement of
people.
Video
monitoring:
is a new trend which uses video to monitor
remote sites in any part of the world. The video images
are transmitted through the telephone network.
Video
motion detector:
is a device which can detect unwanted movement
in the picture and then generate an alarm. |