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4.22. SCENARIOS AND EXAMPLES (SCRIPTS)
#Create the STOP report
>SED30NV4;C01+<
#Create the START report
>SED31NV4;S03C01&+<
#-------------------------------------------
#end
4.22.7 Improving the periodic report
The example we have been working so far uses a time-only criteria
for the periodic tracking report (event
37
). This report is being gen-
erated every 5 minutes 24/7. This includes a lot of useless reports
that show the same location and conditions when the unit remains
stationary. A better approach is to use all three parameters that de-
fine a
Time And Distance signal.
Our actual definition of the T&D signal
8
, which is the signal that
triggers the periodic tracking event
37
is:
>
STD80300
<
As you can check with the
TD
message definition given on the TAIP
reference, this is a time-only criterion which causes the
TD8
signal to
get high on a 5 minutes basis. To achieve a better reporting event,
the T&D criterion has to include all three configuration parameters:
•
Minimum time.
•
Distance threshold.
• Maximum time.
These definitions depend strongly of each user’s situation and it is a
matter of cost vs frequency of report.
Typical values for units on vehicles moving in a city are:
• Minimum time between reports: 2 minutes .
•
Distance Threshold: 2km (1.2mi) .
•
Maximum time between reports: 55 minutes .
The reason for having 55 minutes instead of 1 hour, has to do with
the discussion on having the unit always available for incoming com-
munication, presented on the
Operation chapter.
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