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TTU-12x0 Hardware & Installation Guide - PULS Wiki
https://puls.calamp.com/wiki/TTU-12x0_Hardware_%26_Installation_Guide
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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 TTU-12x0™.
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.
5.2.2 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.
Examples of good and poor GPS antenna placements
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.
