- 20 –
TL25 User guide–- 33-60-021-000
2.3
Autocompensation of the fluxgate compass
It is possible that on some boats, the Fluxgate Compass may be strongly disrupted by its
environment. Despite a careful installation and an offset properly adjusted, an important
difference remains between the magnetic heading displayed and the true magnetic heading,
throughout the measurement range between 0 and 359°. In this case, you must perform an
autocompensation of the Fluxgate Compass to achieve an acceptable level of accuracy.
Please refer to the installation guide of the Fluxgate Compass sensor.
2.3.1 Principle of autocompensation
The operation consists in executing, at a rigorously rotation constant speed, a perfect circle
with your boat, clockwise. While the boat describes this circle, the sensor will record the
measurement points of a deviation curve, every 10° with an accuracy of 0.25°. Thus, your
Fluxgate Compass will be accurately corrected between 0 and 359°.
2.3.2 Autocompensation procedure
In order to achieve a successful autocompensation, you must navigate :
-
On smooth sea, with no current and no wind.
-
Away from large magnetic masses such as cargo boats.
-
In an open area allowing the execution of a circle with a diameter approximately 5 times the
length of the boat.
-
At a constant speed of about 2 or 3 knots.
1. Select, on the upper display, the magn head channel,
2. Select the middle display with the key
3. Start to describe the circle, then press the 8 seconds on the key
▼
, to trigger the
autocompensation procedure.
4. One single circle
*
is sufficient to perform the autocompensation correctly, when its a
success, the message 3000 is indicated.
* For the previous generation of compass, referenced as 90-60-005, at least three circles
must be executed.
In case of problem during autocompensation, the TL25 displays the PAN message , plus one
code :
-
Code 1 : cancellation at user request.
-
Code 2 : detection of a gyration in the opposite direction. Start again clockwise.
-
Code 3 : excessive variation between 2 heading measurements. Reduce the speed of your
boat to 2 or 3 knots.
-
Code 4 : angle correction higher than 20°. Start t he autocompensation procedure over.
In case of autocompensation error, the measurements are not saved to the memory and the
sensor resumes its normal operating mode.
CAUTION : the autocompensation operation of the Fluxgate Compass requires precision
in the execution of the circle : constant speed of 2 to 3 knots and constant diameter of the
circle. If you cannot maintain these two criteria, the autocompensation will not be
successful.
