User's Manual

DRAFT TrimTrac 1.5 Technical Manual v0.3ab 43
2. Remove and reinsert the existing SIM to verify proper installation.
3. Check the TrimTrac 1.5 configuration to ensure the correct PIN is
programmed.
4. Make sure that the SIM card hold-down latch is securely fasten
and all four corners are locked down.
Even in areas with strong GSM service, there may be pockets where GSM service
is poor or nonexistent due to how the carrier builds the network. Contact your
local service provider for information on GSM coverage.
How to Evaluate TrimTrac Placement
The number one rule in GPS is that a GPS antenna with a clear view of the sky
will have better performance than one that has a blocked view. For instance, a
TrimTrac 1.5 placed on the dashboard of a vehicle will almost certainly have
more GPS fixes than a unit placed under the seat or in the glove box, everything
else being equal. The real question is whether the TrimTrac 1.5 will provide the
level of performance required to meet the needs of the application.
The answer to this question is best derived from field-testing of the specific
vehicle and placement options. The test plan should call for at least one unit with
an external antenna that is placed on the roof of the vehicle. This antenna
placement will provide the best possible GPS performance and will establish the
baselined against which all other configurations and placements will be evaluated.
Operate all devices simultaneously. Do not attempt to place a single unit in one
location, do a test drive, and then relocate it to another area of interest. The only
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 1.5, 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 2, 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 1.5
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.