Specifications

FCS1362 Page 45 of 74 © Nov 2010
4.7.2. Isolated supply system checks
Where there is an isolated supply system, it must be ensured that the installed equipment has not
degraded the insulation between each terminal of the battery and chassis, i.e. positive to chassis and
negative to chassis.
Continuity checks, carried out with a suitable multimeter, between the positive and negative supplies and
the vehicle chassis must be carried out before and after installation to ensure isolation of the power
supply is maintained.
The checks should be carried out with the isolation switch in the on position.
4.7.2.1. Isolated converter or regulator checks
Where a converter or regulator is used, ensure the fused supply to the converter is capable of being
switched off. This can be achieved using the isolating switch or via the ignition switch.
4.8. Testing Antennas
It is important to test the antenna installation when complete to ensure that it is operating effectively. This
may also involve tuning the antenna for a mobile radio or specialist installation.
Table 5 - Antenna Test Requirement
Installation type
Continuity check
VSWR test
Cellular GSM/3G Asset
Tracking and AVL
Simple antenna* with pre-
terminated connector
YES
Recommended test
An antenna analyser
(see section 4.8.1)
Cellular GSM/3G Asset
Tracking and AVL
Panel mount or other antenna
with installer fitted connector.
YES
Recommended test
An antenna analyser
(see section 4.8.1)
Mobile Radio, PBR & TETRA YES
It is compulsory to test VSWR.
This may involve tuning the
antenna to match frequency.
*Simple antenna defined as a one piece unit with integral coaxial cable and pre-fitted connector.
Ensure the antenna radiating element is of the type and length specified by the manufacturer for the
relevant frequency in use. It should be noted that most antennas for cellular GSM/3G radio operation are
pre-tuned and not adjustable.
4.8.1. Antenna DC tests
Before connection to the equipment the antenna system should be DC tested at the equipment end of the
coaxial cable for continuity and to ensure there is no short circuit.
A DC continuity check is not possible with a fully encapsulated antenna as the protective cover must not
be broken in order to undertake the test.
The resistance will depend on the length of the co-axial cable running between the connector and the
aerial base. Typically for a motor car it should be less than 0.2 Ohms for the connector body to aerial
base, or ground plane, measurement and 0.3 Ohms for the centre-pin to radiating element, where it is
possible to take this measurement.
For reference resistance measurements of RG58, the typical 50 Ohm co-axial cable used and supplied
as an integral part of aerial bases, indicate a resistance per metre length of approximately 15 milliohms
for the cable’s screen and 50 milliohms per metre length for the inner conductor.