![YSI SonTek RiverSurveyor System Manual Download Page 56](http://html.mh-extra.com/html/ysi/sontek-riversurveyor/sontek-riversurveyor_system-manual_915336056.webp)
SonTek/YSI Inc
RiverSurveyor System Manual (May 1, 2007)
44
3.8.
Compass/Tilt Sensor and Magnetic Declination
The following topics are covered in this section:
•
What is the Compass/Tilt Sensor?
•
How does the Compass/Tilt Sensor work with RiverSurveyor?
•
3.8.1. What is the Compass/Tilt Sensor?
The compass/tilt sensor provides real-time heading, pitch, and roll data to the ADP. The sensor is
installed inside the ADP. The compass can be mounted in either an up or down-looking orienta-
tion (see
ADP Operation Manual
for details on changing compass orientation). By default, Riv-
erSurveyor systems are preconfigured with a down-looking compass orientation.
Compass data is used internally to convert measured water current velocities from the XYZ co-
ordinate system to Earth (East-North-Up; ENU) coordinates. For more information on these co-
ordinate systems, see §
Compass data is also useful as a diagnostic tool to analyze vessel movement during the time of a
measurement. If the ADP is orientated with the X-Axis (marked on the transducer head) facing
towards the bow of the vessel on which it is mounted, the compass sensor will report data rela-
tive to the movement of the vessel (i.e., if the vessel pitches forward, the compass will report the
ADP pitching forward also). Heading is a rotation around the Z-axis, pitch is a rotation around
the Y-axis, and roll is a rotation around the X-axis.
3.8.2. How does the Compass/Tilt Sensor work with RiverSurveyor?
To collect accurate compass data in RiverSurveyor, the compass must first be calibrated to com-
pensate for the effects of ambient magnetic fields. You can select the
Calibrate Compass
option
via the
User Setup
). The
User Setup
dialog box will be displayed each
time you connect to your ADP and run the
RiverSurveyor
program. It can also be displayed by
selecting
ADP Configuration|User Setup
.
You should perform a compass calibration when any of the following occurs:
•
Before collecting data at a new survey site
•
Whenever the ADP mounting method or material is changed
•
Whenever a different vessel is used
•
When GPS is used as a reference to measure discharge
Bear in mind that even though the compass/tilt sensor operates quite well under most surveying
conditions, quick course changes or excessive variation of vessel roll/pitch may affect the quality
of your data. It is good
practice to avoid these
excessive conditions and
keep the vessel’s opera-
tion steady during a dis-
charge measurement.
Figure 3-21. User Setup dialog box – Calibrate Compass
Summary of Contents for SonTek RiverSurveyor
Page 2: ...SonTek YSI Inc RiverSurveyor System Manual May 1 2007 ii ...
Page 4: ...SonTek YSI Inc RiverSurveyor System Manual May 1 2007 iv ...
Page 14: ......
Page 24: ...SonTek YSI Inc RiverSurveyor System Manual May 1 2007 12 ...
Page 26: ...SonTek YSI Inc RiverSurveyor System Manual May 1 2007 14 ...
Page 74: ...SonTek YSI Inc RiverSurveyor System Manual May 1 2007 62 ...
Page 82: ...SonTek YSI Inc RiverSurveyor System Manual May 1 2007 70 ...
Page 148: ...SonTek YSI Inc RiverSurveyor System Manual May 1 2007 136 ...
Page 162: ...SonTek YSI Inc RiverSurveyor System Manual May 1 2007 150 ...
Page 166: ...SonTek YSI Inc RiverSurveyor System Manual May 1 2007 154 ...
Page 168: ...SonTek YSI Inc RiverSurveyor System Manual May 1 2007 156 ...
Page 182: ...SonTek YSI Inc RiverSurveyor System Manual May 1 2007 170 ...
Page 194: ...SonTek YSI Inc RiverSurveyor System Manual May 1 2007 182 ...