User's Manual

DRAFT TrimTrac 1.5 Technical Manual v0.3ab 26
How frequently those logged positions are transmitted, however, is determined
mostly by the Report Delay Flag setting. For instance, if the Report Delay Flag is
set to some value other than “0=Transmit All Messages”, some or all of the
logged positions may not be transmitted unless a QUERY_LOG or similar
message is received by the TrimTrac 1.5 or if the Scheduled Reporting Mode is
set to either “1=Weekly” or “2=Daily”.
Battery Life and Communication Costs
If computing position fixes consumed no power and if communication costs were
“free,” then there would be no need to worry about such things. Alas, such is not
the case. In any given application, there must be an appropriate trade off between
communication costs, power consumption and battery life and the need for
information. Taking into account the foregoing general considerations, the
following sections look at different application scenarios and suggest possible
configurations.
Polling
In its default configuration, the server application can communicate with the
TrimTrac 1.5 only while the device is in the QUERY State, which may not allow
frequent enough communications for some applications. As such, the TrimTrac
1.5 has several different polling options that can be activated depending upon the
appropriate mixture of power consumption, communication costs and the need to
communicate with the device in a timelier manner than allowed by the default
settings.
Depending upon the specific application requirements, the polling capability of
the TrimTrac 1.5 can be selectively turned on and off or simply left on
continuously regardless of motion or current operational state.
For instance, if Anytime Polling is set to “2=Anytime OnDemand”, then the GSM
modem will never be turned off. The device will be able to receive and process
data messages whether the device is at rest or is in motion regardless what
operational state the device may be at the time.
If, on the other hand, continuous polling capabilities are required only while the
device is in motion, then the In-Motion Polling feature would be set
“2=OnDemand while in Motion”. Once the device comes to rest, the GSM
modem would be turned off to save power. It would be powered back up upon
the occurrence of a TriggerType event or whenever the Polling Duty-Cycle On-
Time, T20, is running.
Enabling any polling capability will have a significant impact on power
consumption. Setting the Anytime Polling to “2=Anytime OnDemand” will limit
the life of four AA alkaline batteries to no more than 3-5 days depending upon
how frequently the GSM network pings the device for registration information.
Therefore, any polling mode, except perhaps for Cycled Polling, is best reserved
for those TrimTrac 1.5s using a Vehicle Adapter or Control Module.