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Ultrasonic
sensor:
is a type of alarm which works
on the principle of high frequency sonic
emission to detect movement in a zone.
Ultraviolet:
is electromagnetic radiation
with a wavelength of less than 400 nm
and is not visible to the human eye.
Unbalanced
cable:
is a type of cable in which the
ends of the shields are grounded to different
equipment with possibly varying ground
potential. This unbalanced set up can
give rise to ground loop currents and
EMI induction.
UPS
Uninterruptable Power Supply:
stores electricity and supplies
power to a CCTV system during a power
failure.
Usable
video:
is the minimum video signal specified
in the camera data sheet to generate an
acceptable picture on the monitor. It
is usually measured as a percentage of
the full video.
Example:
30% usable video = 30% of 0.7 volts
(full video or maximum video amplitude)
= 0.2 volts
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