Installation
Antenna Installation
34
SRL-35 Operator’s Manual P/N: 1003224-01
Power Supply
The allowed operating voltage is +9 ... +16 V
DC
. The radio modem must only be connected to a power
supply with an adequate current output (power rating minimum is 150W). The pins 1 and 2 of the 4pin
Odu-connector are connected to the positive power supply line. The pins 3 and 4 are connected to negative
power supply line (ground).
Antenna Installation
Mobile Equipment
•
¼-wave antenna
•
½-wave antenna
The ideal installation position is vertical, and there should be at least 0.5 m of free space around the
antenna. In small systems a ¼-wave antenna is sufficient. A separate ground plane should be placed under
the antenna (vehicle rooftop or the engine hood or trunk door are usually suitable). In problematic cases
the most suitable type is a ½-wave antenna. It can be installed directly at the top of a pipe with the added
benefit of gaining as much as free space around the antenna as possible. In cases, which the antenna
cannot be directly connected to the TNC-connector of the radio modem, a coaxial cable with 50 ohm
impedance must be used between the antenna and the TNC-connector.
Base Stations
•
Omni-directional antennas ( ¼- , ½- or 5/8-wave antenna)
•
Directional antennas (yagi /multi-element antenna or corner antenna)
The antenna should be installed in a vertical position. The exact location of the antenna depends on several
factors, such as the size of the overall system and the coverage area terrain contours. A rule of thumb is
that the base station antenna should be located at the highest point of the coverage area and as close to
the center of the coverage area as possible. The base station antenna can also be located inside a building,
if the walls of the building do not contain metal.
General Antenna Installation Instructions
The reliability and the achievable coverage of useful signal strength can be severely affected by the
positioning of the antenna. Antenna and cable connectors should have gold-plated pins and sockets, as use
of low quality connectors can lead to eventual oxidation of the connector surfaces, which in turn may
degrade the contact and cause additional attenuation. Good quality tools and materials must be used when
installing radio modems, antennas and cables. The weather tolerance of the materials used must also be
taken into account. Installed materials must withstand all foreseeable weather conditions (frost, excess
sun, direct UV-radiation, seawater etc.). Also possible environmental pollution must be considered (acids,
ozone etc.).
Because of the great transmission power of the SRL-35 radio modem, only an external antenna is
allowed. A whip-antenna directly connected to the antenna connector must not be used.
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