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. |
