User manual

MPTP | MPTP commands 24
*) cf. section 3.1 for description of these fields.
The Data field includes beacon data if position format is 3. Some TWIG instruments use it also to hold
textual information about the cause of failure when unable to acquire a position fix.
Beacon data in above example. Different fields within Beacon data is separated with “.” (full stop):.
Different Beacons are separated with”_” (underscore). Underscore (“_”) must NOT be used in Beacon
name.
ROOM1.5.-101.35.25_
Field
number
(example)
Description Range
1 (ROOM1)
Name of the Beacon. If no name is give
the serial number will be tranmitted
0…8
2 (5)
Beacon transmit level.
0=10dBm
1=7dBm
2=5dBm
3=0dBm
4=-10dBm
5=-20dBm
6=-30dBm
Default 5 (-20dBm)
0..3
3 (-101)
Reception signal level in dBm
0..4
4 (35)
Battery voltage level 1/10V
0..2
5 (29)
Timestamp offset in seconds between beacon
data received by TWIG and time of sending
the data via MPTP
0..4
4.2. Tracking commands
Tracking is a function which enables monitoring a target’s position and movement without having to
specifically request it all the time. This is done by setting up a tracking process on a terminal to take care
of automated sending of position information.
Tracking processes
A tracking process is defined by the following attributes:
Start trigger :
The tracking process is started when this condition is met.
Typical start triggers include a specific time, entering or exiting an area, or raising the speed of
the terminal above or dropping it below a limit. It may also be desirable to have a tracking
process start as soon as it is created, in which case it has no start trigger.
Interval :
While running, the tracking process sends messages with position information at a specified
interval. Such messages are called tracking reports. The first report is sent as soon as the start
trigger condition is met.
If needed, the GPS receiver may be automatically switched on at the specified interval to facilitate
acquisition of a new position fix for each report.