TrimTrac ProE Locator, Technical Manual

Page: 90 / 233

TrimTrac ProE Locator Technical Manual v2.0e 72
way to truly test different placements is to have one device in each location
operating simultaneously with all the other units.
An example evaluation plan might be to have one device with its external antenna
placed on the roof, one unit operating on the internal antenna on the dashboard
with a clear view of the sky, one unit in the glove box and one under the front
seat. This would require a total of four units, all identically configured.
To maximize the amount of data, we recommend using the factory default
configuration, except the DELAY Timeout, T4, should be set to the minimum of
10 seconds. If an active SIM card is inserted in the TrimTrac ProE, then this will
result in a new message being logged every 2 to 3 minutes for the unit operating
on the external GPS antenna placed on the roof (See Figure 21. Expected
Reporting Frequencies). If no SIM card is inserted, then the TRANSMIT and
QUERY states are skipped, resulting in more frequent message logging.
The vehicle should be operated as one would expect in the actual application
environment. The data logged by the roof-top antenna equipped TrimTrac ProE
will provide a performance baseline against which the other units will be
compared. The analysis should compare the number of attempted position fixes
versus the number of successful position fixes during the test period by unit.
In general, testing done to date indicates that a unit located in the glove box will
on average get approximately 50% fewer position fixes than a unit located on the
dashboard of the vehicle. Units placed under the front seat will performance
about the same as units placed in the glove box unless the seat is a power seat.
Power seats have considerably more metal than manually adjusted seats and the
added metal attenuates the GPS signal that much more. It is not recommended
that units be placed in the trunk of standard 3-box style sedans unless an optional
external GPS antenna is used.
GSM Jamming
The TrimTrac ProE, or the optional external GPS antenna, should be installed as
far away as possible from other transmitting antennas including other TrimTrac
ProEs, satellite communication, radar, and VHF radio. These transmitters may
emit jamming signals that interfere with the GSM phone’s ability to track the
GSM signal. If there are other transmitting antennas located on the vehicle, try
moving the TrimTrac ProE farther away from these antennas. Generally, the
stronger the other transmitting device, the wider the distance required between
antennas.
No Data Communication via Provisioning Module
If you were able to communicate with an original TrimTrac using the
Provisioning Module and a PC running HyperTerminal, then you should also be
able to communicate with a TrimTrac ProE. Please make sure that you have
loaded the proper FTDI driver and configured HyperTerminal as described in
section Provisioning Set-up beginning on page 109.
If you continue to experience problems, then do the following: