User's Manual

GlobalTrak ™ GT Lite Operation and Maintenance Manual
GPS Configurable Parameters
1. GPS mode
GPS mode sets the GPS receiver to be in acquisition mode or continuous tracking mode.
2. A-GPS mode
The use of assistance data can be configured in three ways: Always, never, or on cold
fix. If ‘on cold fix’ is selected, GT Lite will only request assistance data on boot or if a
hot or warm fix fails. With the firmware addition of AssistNow Offline, this mode will be
added to the configuration, as well as an assistance download interval.
3. Hot/Warm start timeout
The hot/warm start timeout is used if there is sufficient data for a hot or warm start.
The GPS receiver will attempt to acquire a 3D fix for the time allotted. If the hot/warm
start timeout is 0, GT Lite will always use the cold start timeout
4. Cold start timeout
The cold start timeout is used on boot, or after a hot or warm start fails. It is typically
much longer than the hot/warm start timeout to accommodate longer fix times. If A-
GPS mode is set to ‘on cold fix’, GT Lite will download assistance data before attempting
the cold fix. If the cold start timeout is set to 0, GT Lite will not attempt a cold fix after
a failed warm fix and all fixes will be attempted using the hot/warm start timeout.
5. Cold Start Lockout
To conserve additional battery used from long cold start timeouts, GT Lite will only use
the cold start timeout for a configurable number of consecutive attempts (Cold start
lockout). If the cold start lockout is reached, the GT Lite will only use the hot/warm
start timeout. The lockout is reset after a successful fix is acquired. Setting the cold
start lockout parameter to 0 never locks the GT Lite from using the cold fix timeout.
Data Storage and Logging
The GT Lite stores all sensor data in the form of Logging Records to non-volatile memory at a
programmable interval as well as any alarms. The logs contain peak sensor data over the
logging interval along with a time stamp. The alarm logs contain the sensor data at the time
of the alarm with a time stamp.
Log Storage Capacity
The GT Lite allows for the storage of up to 500 messages in NV memory.
Log Storage Viewing
The GT Lite shall allow for viewing of the Logging Record storage, initiated by command over
the main serial port.
Log Storage Clearing
The GT Lite shall allow for clearing of the Logging Record storage, initiated by command over
the main serial port.
Power Source
The main GT Lite power source is an internal battery, capable of sourcing sufficient pulse
current for RF transmission with output voltage not less than 3V (even during RF
transmission) and not more than 4.2V. The battery used is one lithium ion cell providing a
nominal voltage of 3.6V. This is a rechargeable battery; however charging is possible over a
limited temperature range compared to discharging.
Prepared: R. Straz Date: July 25, 2007 Page 24 of
139