R2Sonic 2026, Operation Manual

Page: 168 / 254

Page 168 of 254
Version 6.3 Rev r012
Date 05-11-2022
Part No. 96000001
Graph 4: Along-track position error caused by 1.0° error in yaw patch test error
11.4 Solving for the Patch Test
Depending on the data collection software that is employed and how it solves for the patch test,
there will be a distinct order that the tests will be solved for, but this does not influence the data
collection for the patch test. In general, latency will be solved before pitch; roll will be solved before
yaw. It is not uncommon that a larger than expected error in one of the tests will make it necessary
to go back and resolve for all previous values. This can be the case with a large yaw offset, as this
will influence to a greater degree the accuracy of the latency and pitch computations if done using a
slope.
The resultant patch test values are corrections that are entered in the data collection software and
not in the Sonic MBES software, as the values are used for process data.
11.5 History
Since the advent of commercial multibeam echosounders, there has been the need to measure
the angular offsets between the multibeam sonar head and the auxiliary sensors that provide
attitude and heading information. Another measurement is made to determine the latency in
the GPS receiver. Multibeam data is collected that is used to determine (1) latency, (2) roll offset,
(3) pitch offset and (4) heading or yaw offset
What has been developed is called the Patch Test; this is the multibeam calibration. During the
development of the data collection criteria, for the Patch Test, there has only been a basic
description for the manner of the data collection; providing little, if any, directions that would
help create a high degree of confidence in the results of the various tests. This section will
address those very directions that will help create a highly accurate and statistically viable
result from the Patch Test.
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-100 -50 0 50 100
Alo
ng
-tra
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P
os
iti
on
E
rro
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et
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Angle from Nadir
Position Error with a Heading Error of 1.0°
200 metres
150 metres
100metre
50 metre
25 metres
10 metres
Water Depth