Vector Sensor Reference Manual 93
Note - It is very important to perform the calibration only after the installation of the
Vector Sensor has been confirmed to be complete. If the Vector Sensor’s location is
changed, you will need to clear the calibration and recalibrate. A valid GPS heading is
required during the calibration process.
6.8.6 $JATT,GYROAID
The Vector’s internal gyro is shipped on by default, and it offers two benefits. It will shorten
reacquisition times when a GPS heading is lost, due to obstruction of satellite signals, by reducing
the search volume required for solution of the RTK. It will also provide an accurate substitute
heading for a short period (depending on the roll and pitch of the vessel) ideally seeing the system
through to reacquisition. This is why we highly recommend you leave the gyro aiding on.
Exceeding rates of 30 degrees per second is not recommended since the gyro cannot measure
rates beyond this point. This is a new recommendation since we now use gyro measurements to
get a heading rate measurement.
To turn on the gyro-aiding feature, use the following command.
$JATT,GYROAID,YES<CR><LF>
If you wish to turn this feature off, use the following command.
$JATT,GYROAID,NO<CR><LF>
If you wish to request the status of this message, send the following command.
$JATT,GYROAID<CR><LF>
Every time the Vector is powered, the gyro goes through a ‘warm-up’ procedure. This warm up
calibrates the gyro to a point where it is operational to its fullest potential. The gyro will
automatically warm up by itself over the span of several minutes. This ‘self-calibration’ is the
equivalent to performing the procedure below. You may wish to follow this procedure if you need
the gyro fully calibrated at a certain time.
When your Vector unit is installed, apply power and wait several minutes until it has acquired a
GPS signal and it is computing heading. Ensure that the gyro-aiding feature is on by issuing a
$JATT,GYROAID<CR><LF> command. Then, slowly spin the unit for one minute at a rate of no
more than 15 degrees per second. Then, let it sit stationary for four minutes. Your Vector’s gyro is
now fully calibrated. Since this setting cannot be saved, this procedure must be performed every
time the Vector’s power is cycled.
6.8.7 $JATT,LEVEL
This command is used to invoke the level operation mode of the Vector Sensor. If your
application will not involve the system tilting more than ±10° maximum, then you may choose to
use this mode of operation. The benefit of using level operation is increased robustness and faster
acquisition times of the RTK heading solution. By default, this feature is turned off. The command
to turn this feature on follows.
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