Klein Marine Systems, Inc. HydroChart 5000, Operation And Maintenance Manual

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Bathymetric System Calibration and Patch Test
3-17
3.10.4 Yaw Bias Test
For the yaw bias test the objective is to determine azimuth offset error between the
motion reference unit and the sonar arrays. For this test it is recommended that the
survey vessel run two pairs of adjacent lines on reciprocal headings over a flat
bottom with a prominent bathymetric feature, such as the edge of a ship channel.
The adjacent lines should overlap by 10–20%. In computing the azimuth offset, the
data from the reciprocal lines can be used to remove any roll offset. The parallel
lines run in a direction normal to the bottom feature can be used to compute the
azimuth offset using several measurements of the across-track displacement.
3.10.5 Roll Bias Test
This test determines the athwartship alignment error between the transducer arrays
and the motion reference unit as well as any additional roll axis bias error in the
motion reference unit. The result is a roll correction which can be used during post
processing operations. For the roll bias test you should choose a relatively flat area
of the sea bottom and run at least two reciprocal lines 200–300 meters in length at
equal speeds in both directions.