User's Manual

DRAFT TrimTrac 1.5 Technical Manual v0.3ab 42
GPS Almanac Loading
A current almanac can be collected from any operational TrimTrac 1.5 using the
PC-based TrimTrac GPS Almanac Tool. This collected almanac can, in turned,
be loaded into any other TrimTrac 1.5.
Converting GPS Time (UTC), GMT and Local Times
Sample source code for converting GPS (UTC), GMT, and local times is available
on the www.trimtrac.com
/documents partners’ page.
Orientation
The TrimTrac 1.5 should be at a slight incline, preferably with a reasonably clear
view of the horizon and sky. If something on the vehicle—for example, the air
conditioning unit on a cab or the trailer connected to a tractor—blocks a
significant portion of the horizon and the GPS signals, the GPS receiver will take
longer to acquire enough satellites for a position fix. If the TrimTrac 1.5
frequently times out before completing a position fix, try moving the TrimTrac
1.5 to a new location where it, or the optional external GPS antenna, is not
blocked as much.
GPS Jamming
The TrimTrac 1.5 should be installed as far away as possible from transmitting
antennas, including satellite communication, radar, VHF and cellular. These
transmitters may emit jamming signals that interfere with the GPS receiver’s
ability to track GPS satellite signals. Generally, the stronger the other transmitting
device, the wider the distance required between antennas. For the TrimTrac 1.5,
Trimble recommends a minimum clearance of 46 cm (approximately 18 in.) from
these transmitting devices.
Land-based transmitters, including microwave and television transmitters, can
also interfere with GPS reception. If the TrimTrac 1.5 is operating near an
antenna farm, the TrimTrac 1.5 may temporarily lose GPS reception while in the
vicinity of the transmitters. Reception should return once the TrimTrac 1.5 moves
away from the transmitters. If your GPS signals are being jammed and moving
does not correct the situation, the source of the jamming signal may be another
antenna mounted too close to your TrimTrac 1.5. If possible, turn off the
equipment using other nearby antennas to see if this corrects the problem. If
turning off nearby equipment un-jams your GPS signals, you need to relocate one
or more of the jamming antennas.
Poor GSM Coverage
Check to make sure the SIM is not missing or incorrectly installed. Also, check
to confirm that you are using the correct SIM PIN as required by your SIM card
provider. Do the following:
1. Insert a SIM if none is present.