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----------------------------------------------------------------------------------------------------------------------------------------------------------- 10.3.11 Personal Equipment
10.3.12 Methods of using Personal
Radios
'Personal' equipment is small enough to be carried
in the hand or pocket, or in a suitable lightweight
Personal set communication can be organised in a
body-harness. Its small size means miniature con-
number of different ways to meet various opera-
struction techniques which create problem in the
tional needs which, in broad terms, break down
receiver, but which do create difficulties in the
into the following categories:
transmitter. The battery size is severely limited and
those two factors restrict the transmitter power to a
Direct person-to-person communication on
fraction of what is obtainable from 'transportable'
an exclusive single frequency channel over
equipment (normally approximately 1 watt in the
very short distances e.g., between individuals
majority of equipment). This, coupled with the
at an incident, or when carrying out dry riser
restricted aerial dimensions and efficiency, limits
tests - or other duties - in high rise buildings.
the range of the transmitter section. The receiver
performance will be comparable to that of a trans-
Similar communication but in which one of
portable under similar conditions.
the units is mounted in a vehicle.
Personal equipment can operate in either the VHF
Two-frequency communication between per-
or the UHF band, but VHF equipment, other than
sonal sets via a vehicle-mounted or portable
in the single frequency mode, would normally be
VHF repeater.
expected to transmit into the main scheme hill-top
sites. VHF equipment is perfectly satisfactory on a
Two-frequency communication between per-
single frequency basis to other personal, trans-
sonal sets and the brigade control room via a
portable or mobile units over short ranges, but in
vehicle-mounted UHF/VHF repeater.
general UHF offers better performance for person-
al radios. The use of FM offers advantages for per-
Single Frequency Operation
sonal radios, if only because it permits greater
transmitter power to be obtained from a given size
Figure
10.13 (1) involves personal sets only and,
of battery, and all UHF personal radios used with-
although only two are shown, any number can be
in the fire service operate on FM.
used on an 'all-hear-all' basis subject to the limita-
Figure 10.13
(1) Single-frequency
personal set usage.
(2) Single-frequency
personal sets with
control set.
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