YSI SonTek RiverSurveyor, System Manual

Page: 158 / 194

SonTek/YSI Inc
RiverSurveyor System Manual (May 1, 2007)
146
The section you measured the first time is not the same section used in other measurements.
•
Try to avoid making measurements when flow conditions could change significantly over a
short time (e.g., before and after a dam has released water into the stream).
•
Make sure the site depth and location that you measured for the first transect match the
measured values for the second transect. You may have moved up or downstream since the
last transect. Visible landmarks are always a good guide when making a measurement.
Check your positional and depth measurements for both transects.
•
Make sure the distance made good (DMG) is consistent between transects.
•
Make sure the transect track did not reverse at any time, or change track direction.
•
The acceptable error between two to four measurements is typically 2-5%, depending on
your application.
9.10. Compass Calibration Conditions
I cannot get an acceptable result during compass calibration.
You may have not followed the calibration instructions.
The ADP may be mounted in an area of significant magnetic interference (e.g., near the engine).
The ADP mount may be the source of magnetic interference.
•
Repeat the calibration process.
•
Move the ADP mount to a different location on the vessel.
•
Make sure the mount itself is not causing magnetic interference to the ADP.
•
Make sure the tilt angles (pitch/roll) of the ADP do not exceed 45° at any time.