User's Manual

Galaxy Tracking Systems, L.L.C. Technical Documentation - VTU
ONE SHOT
The one-shot command is a request for a single position / status report. The VTU
responds with a single IN SERVICE message containing current status, position, speed
and time.
ACTIVATE TRACKING
The ACTIVATE TRACKING command causes the VTU to begin regular position
reporting. The rate and the exact moment at which the VTU reports and the frequency on
which the report is transmitted are all contained in the command. Tracking mode is used
to monitor vehicle movements and status in real-time and to vector pursuit vehicles to
intercept points.
DEACTIVATE TRACKING
Position reporting ceases when DEACTIVATE TRACKING is commanded. The VTU
responds with one last IN SERVICE message to indicate the change in tracking status.
Commanding the VTU OUT OF SERVICE also stops tracking reports, however, in this
case, the VTU responds with a single OUT OF SERVICE message to report its change in
operating mode.
POLL REQUEST
The POLL REQUEST equivalent to issuing a ONE SHOT to every member a group
(fleet) of vehicles. Upon receipt of a POLL REQUEST each VTU will compare the
transmitted poll information to poll classes defined internally. If there is a match, the
VTU will transmit an IN SERVICE message at the frequency and in the time slot
specified in the matching poll class. Poll classes are factory configured to allow low
priority status reporting for large groups of related vehicles.
Poll responses are low priority. If the VTU is responding to a command or a self-
activation the poll request is ignored. A scheduled poll response is automatically canceled
if the VTU receives a command packet or self-activates. Polls do not extend beyond the
end of the 30-second cycle in which the poll was requested. If the VTU schedules a poll
response, it will ignore any new poll packets until the scheduled poll response completes.
SELF ACTIVATION (SOS)
A vehicle (VTU) does not report its position on a regular basis until it is commanded to
ACTIVATE by the command center. In emergency situations, however, the VTU can
request to begin regular position reporting in order to be tracked by “SELF
ACTIVATING”.
The conditions that can result in SELF-ACTIVATIONS are SOS, request for roadside
assistance, unauthorized movement and vehicle alarm. SOS and the roadside assistance
requests are initiated when the operator depresses a switch (if equipped with the switch
box option). If the operator has armed the VTU motion sensor (included in the switch box
Use or disclosure of data contained on this sheet is subject to the restriction on the title page of this report.