SonTek, a Xylem brand
24
RiverSurveyor S5/M9 System Manual (February 2013)
Spread Spectrum base radio is battery powered, so be sure to have fully charged batteries and
to turn it on prior to starting the discharge measurement.
5.3.3.
System Test
This is a 60 second verification that the components of the hardware are functional. The System
Test verifies the battery voltage, compass, SD memory card and temperature sensor are all
functioning properly. A system pass would indicate that all systems are sound for use, while a
fail would require user action in order to conduct reliable discharge measurements. Below is a
list of the system Fail messages:
System battery voltage < 12 volts
System compass is not working
System SD card (memory) is not working
Temperature sensor is not working
5.3.4.
Compass Calibration
Compass calibration is necessary prior to each discharge measurement. It is used to compen-
sate for magnetic interference in the vicinity of the ADP. A battery or steel clamp right next to
the unit will have a much greater effect than, for example, a steel bridge 200 m away. That’s
why it is important to eliminate any magnetic material, including electronic/mobile devices and
wristwatches from the immediate vicinity when performing a compass calibration.
To perform a compass calibration, rotate the ADP through two complete circles while varying
pitch and roll angles as much as possible. Each rotation must take no less than one full minute
to complete.
If the ADP is to be mounted on a boat, the
entire
boat needs to be rotated for the calibration,
along with everything that is physically attached to the system, while varying the pitch and roll
angles as much as possible (within the limitations of the vessel). Changes to metal components
on the boat (such as toolboxes, engines or mounts) should not be made after the calibration is
done, otherwise, the calibration must be repeated.
If a good calibration score cannot be achieved, try to reduce the speed of the rotations and in-
crease the pitch and roll as much as possible. It may be necessary to complete the compass
calibration by hand on the boat as close to the mounting location as possible. Heading correc-
tions can be made in post-processing if necessary.
The compass calibration routine was updated in firmware v3.00. The new compass calibration
procedure improves the ability to detect local magnetic distortion and provides detailed feed-
back about the result. The improved magnetic north heading readings during the actual calibra-
tion are used to reference “True North”. Improved magnetic north readings reduce the need to
make minor heading corrections in order to properly align the compass to true north. Details
about the software feedback can be found in Section 6.9.1.
