User's Manual

GlobalTrak ™ GT Lite Operation and Maintenance Manual
Motion Sensor
The motion sensor is a normally closed sensor that detects vibration of GT Lite. While the GT
Lite is moving, the sensor reports the motion state as In Motion. While still, the motion state
is reported as Stationary.
The sensor output is constantly monitored and edge triggered, even when the GT Lite is in its
lowest power state. Following first indication of a possible change of state, the sensor is
sampled for a configurable time period, and an event is declared only after all consecutive
readings indicate such. The sampling period for a high to low (begin motion) and low to high
(end motion) are separately configurable. For a confirmed motion event, the GT Lite
immediately generates a message and sends to the IMB. Both sampling periods (begin
motion and end motion) shall be user programmable, changeable over-the-air through the
GSM network or locally. Also the threshold can be disabled, such that no event message is
generated.
The motion and stationary reporting intervals are also user programmable, changeable locally
or over the air through the GSM network.
The motion sensor also allows for different reporting intervals whether in motion of
stationary. This allows for still assets to report less frequently to conserve battery.
Accelerometer
The accelerometer is a three-axis MEMS device within the GT Lite enclosure. The
accelerometer is available in ±18g, ±6g, and ±3g varieties, depending on the application.
The standard configuration contains the 18 variety.
The accelerometer can function in two modes: A low power threshold detect mode and a
higher powered sampling mode.
The threshold detect mode sets the accelerometer to internally read the acceleration data and
compare it to a set threshold. Once the threshold is crossed, the accelerometer wakes the GT
Lite processor because of the event. The GT Lite immediately creates an event and sends it
to the IMB. Normal acceleration data is not available in this mode.
In sampling mode, the low power processor reads from the accelerometer to determine if a
threshold is crossed. Once the threshold is crossed, the GT Lite immediately creates an event
and sends it to the IMB. Normal acceleration data is available in this mode, allowing for real-
time acceleration data if needed. The sensor is re-armed after the sensor level returns from
the alarm state. At the point where the sensor level crosses the threshold back to a typical
level the sensor alarm is once again active.
The mode of operation and shock threshold are both programmable, changeable over-the-air
through the GSM network or locally. Also the thresholds can be disabled, such that no event
message is generated. Disabling the threshold and setting the mode of operation to threshold
detect, turns off the accelerometer for power saving.
Note, sampling mode is not currently available.
Analog Input
The single analog input is translated to 10-bit digital representation. Furthermore, the analog
input provides for the following:
i) ESD protection (8 kV contact, 15 kV air)
Prepared: R. Straz Date: July 25, 2007 Page 18 of
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