B C D
E F G
H I J
K L M
N O P
Q R S
T U V
Ultra High Frequency signal. In television it is defined to
in the radio
spectrum between 470 MHz and 850
In CCTV, this refers to a type of video signal transmission through a
coaxial cable. It is called
unbalanced because the signal travels through the centre
returns via an earthed condutor.
One conductor is a fixed voltage ie earth and only the other
moves. In a balanced line
system neither conductor is referenced to earth.
raster size in both H and V so that all four edges of the picture are
visible on the
Power Supply. These are power supplies used in the majority of
security systems, whose purpose
is to back-up the system when the mains power fails. The
duration of this depends on the
size of the UPS, usually expressed
in output VA (or kVA), and
the hold up time expected from
fully charged batteries. There are two common types, "off line"
and "on line". Off line uses
a switch to change from mains to battery operation, thus there can
be a short break in the output.
On Line UPSs are a type where the convertor is always working,
hence there is no switch over break
at the ouput..
UTP. Unshielded Twisted
Pair. A cable medium with one or more pairs of twisted insulated
copper conductors bound in a single
sheath, with no overall or individual screen. Now the most
of bringing telephone
signals and data to the desktop.