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9/28/23, 4:30 PM
6.2 Plan the Installation
Verify Power, Ground and Ignition. Be sure to check each source (power, ground and ignition) to ensure that the proper signaling exists. This is typically accomplished
with a multi-meter.
Before drilling any holes or running any wires, decide where each hardware component will be located (LMU, antennas, peripherals, etc.). Be sure that the cables to the
LMU are not bent or constricted in any way. Also make sure that the LMU is kept free from direct exposure to the elements (sun, heat, rain, moisture etc...).
Be advised that an installation that violates the environmental specifications of the LMU will void the warranty.
The best way to ensure a trouble-free installation is to consider your options and make some decisions before you start. Take a look at the vehicle and determine how to
best install the LMU for the following purposes:
Accurate data gathering and simulation of how customers actually use your solution
Ongoing monitoring and maintenance of LMU equipment
Accidental or intentional alteration of the equipment or cable connections
The following sections cover some of the issues to consider when planning your LMU installation.
6.2.1 Size and Placement of the LMU Unit
The dimensions of the LMU should be taken into account, particularly when installing in a vehicle: Whether you intend to place the LMU under a seat or into a cavity
behind the vehicle's interior molded trim, be sure the LMU will fit before drilling any holes or running cable
Be certain that the cables running to the LMU will not be bent or constricted. Damage to the cables may impede the LMU's performance
Be certain that the installation point will not violate any of the LMU's environmental specification (temperature, moisture, etc...) as improper installation of the
LMU may void the warranty.
See the LMU Environmental Specifications for the exact measurements and specifications of the LMU-5541™.
Typical installations will place the LMU under the vehicle dash board, or in the trunk. Make sure you can get access to the unit afterwards as under some circumstances it
may be necessary to add additional wiring or connections to the LMU.
6.2.2 Placement of Antennas
There are effectively three options for placements of an antenna:
Roof-mount (magnetic or thru-hole)
Glass-mount
Covert (e.g. under the seat, dash, etc...)
Comm Antenna Placement Guidelines
The Comm. Antenna must be located at least 20cm away from vehicle passengers, other personnel, or bystanders in order to comply with FCC radio frequency exposure
limits.
Typically, the Comm antenna used by the LMU for wireless service is a standard 3-dB gain whip. It mounts with standard mounts (i.e. thru-hole, magnetic mount or peel
and stick) and requires a ground plane to work properly. If possible, it should be located at least 3 feet from the GPS antenna. Ensure that the cable does not get crushed
during installation.
Please note that the antennas provided by CalAmp combine both the GPS and Comm portions.
GPS Antenna Placement Guidelines
In order to maximize the performance of the LMU the GPS antenna should have a clear view of the sky. When installing the GPS antenna on a vehicle, make sure that
there are no obstructions close to the antenna that might block the view 360° to the horizon. Things like air horns, lights, vents, etc... should not block the antenna beyond
5° above the horizon. The best location is usually near the center of the roof; however it is also desirable to locate the cellular antenna as far from the GPS antenna as is
practical.
The received signal levels at the GPS antenna from the satellites are very low in power (approximately -136 dBm), so any blockage of the antenna can affect the quality of
the location computed by the receiver. Kinks or tight knots in the antenna cable can also prevent the GPS receiver from operating properly. When laying out the antenna
cable, care should be taken so that the cable is not subjected to crushing or strain.
Placement of Combination and Internal Antennas
https://puls.calamp.com/wiki/LMU-5541_Hardware_%26_Installation_Guide
LMU-5541 Hardware & Installation Guide - PULS Wiki
Examples of good and poor GPS antenna placements
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