Rover User Manual Version 3.0
25
Note:
If a watch circle is not set by command, but
functionality is enabled, the Rover will average its GPS
location fixes for 48 hours. The device will create a
Watch Circle using the 48-hour average as its centre
and a user-definable radius (default radius is 100m)
Watch Circle
The watch circle functionality allows users to monitor the position of their mooring by receiving
alarm messages when it exits a user-defined circle. This feature aids in the recovery of moorings
that could break free from their planned position.
Recognition of a watch circle exit is tied to the GPS interval of the device in Normal Mode (Timer
0); once a GPS position is logged that shows the device is outside the circle, the device
immediately transitions to Alarm Mode (Timer 2) and transmits according to Alarm Mode timer
intervals.
Enabling the Watch Circle
The watch circle is disabled by default, but can be enabled by the following command:
$WCenable 1
The device will respond with a Switch message in ASCII showing watch circle (component C) is
moved to the Y (yes) column.
Once functionality is enabled, the specifics of the user’s circle can be implemented.
Setting the Watch Circle
The watch circle parameters can be set by sending the $setcircle command using this format:
$setcircle
Latitude
Longitude
Radius
The minimum Radius is 50 meters, while the maximum is 15000 meters.
Example:
$setcircle
47.56989
-53.55682
100
a)
$setcircle
is the command
b)
Latitude is set to
47.56989
c)
Longitude is set to
-53.55682
d)
Radius is set to
100
meters
Upon implementing the watch circle, the Rover will return an S-Type message (see below):
Once the watch circle is set, the unit will operate normally until it approaches the watch circle
radius, at which point the device will send a warning message. Once the device exits the watch
circle radius, it will begin sending alarm messages with GPS coordinates every 10 minutes (Timer
2) until the unit re-enters the watch circle, the radius is expanded via command, or is turned off.
Notes
A maximum of 24 GPS positions can be included in a single SBD transmission. Unlike other
settings, the watch circle’s details are erased at each power up.
Watch circle alert, watch circle warn and inverted mode use the same timer.
You can adjust the Watch Circle’s radius alone by setting the latitude and longitude
parameters to 0, followed by the new radius.
