September
2017
Sentinel V SC and RT Operation Manual
Page 114
EAR-Controlled Technology Subject to Restrictions Contained on the Cover Page.
Compass Calibration
At high dip angles (which occur at latitudes near the magnetic poles) special care must be taken when cali-
brating the Sentinel V compass. First, the system must be tilted correctly (40 degrees for the first four car-
dinal directions and 65 degrees for the other eight calibration points) to ensure that the calibration points
provide good coverage of the X, Y, and Z axes. Second, and possibly more important, is that at high dip
angles the component of the magnetic field used to determine heading becomes very small. As such, the
Sentinel V compass becomes highly sensitive to any external influences seen during calibration, so it is
important to ensure the calibration is performed in the most magnetically “clean” environment possible.
TRDI recommends that if you are having trouble calibrating the Sentinel V compass that you move the
system and/or ensure the area around the system is clear of electrical equipment and ferrous materials.
To calibrate the compass:
1. Go outside, away from magnetic materials.
2. For Self-Contained systems, start ReadyV (see
). Use the
panel to start the compass calibration. The last compass calibration score will display. Press
the Calibrate with no fixture button to start.
For Real-Time systems, Start Sentinel V RT Utilities and connect to the Sentinel V Real-Time (see
Connecting to the Sentinel V Real-Time
). Click Compass Calibration. Under Calibration
type, select Without calibration fixture. Press the Start Calibration button to start.
3. Place the Compass Calibration Guide on a wood or plastic test platform at least 1 meter (~3 feet)
high to move away from metal under the ground.
Try using a plastic cart with the system positioned with the transducer head above the fixed
(non-swiveling) wheels on the cart. This allows you to spin the cart around to change
directions without moving the compass too much around in space.
Note that the Calibration Step 1/START point of 0 degrees rotation is not an absolute heading
direction; it
can be in any (arbitrary) direction. For ease of use pick north or south or east or
west of some other reference such as straight line(s) on the ground.
Use the beam numbers embossed on the side of the transducer assembly to orient the ADCP.
Use a wood or plastic test platform at least 1 meter (~3 feet) high to get away from metal
under the ground.
Place the ADCP on the Compass Calibration Guide or stand in the same orientation as it will
be deployed (i.e. up or down).
Use the transducer cover to protect the ADCP transducer faces during calibration.
Have one person hold the ADCP while a second person operates ReadyV.
