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Re running the same
test with the offset
modified is another
way to check the
sign has been en-
tered correctly. The
object will not move
if everything is cor-
rectly configured.
Page 64 of 68
Installation Manual
Advanced Optional Patch Tests
Sea Trial - Commissioning Step 16 : Additional Patch Tests (Optional)
If the WASSP system is fitted with high accuracy sensors significantly better
performance can be expected. The 160/80F system is designed for low end
sensors and thus has a moderate amount of correction configuration available.
For operators using a standard GPS with a built in Motion Sensor like the SC30
the following tests will likely make the system configuration worse and thus are not
recommended.
Pitch Correction (Optional)
Requires: 40m+ depth, Distinct Object, DGPS or better, Accurate Time Lag
Once the Time Lag is accurately ascertained using the variable speed method
described in the previous commissioning step. A Pitch Correction value can be
ascertained by having the Ship travel over a distinct object in opposite directions.
The Object will move if the Pitch offset is incorrect and use of trigonometry will
determine the Pitch offset of between the Motion Sensor and the Transducer.
Enter this number into the Pitch Offset on the Sensor Values Tab.
The 160/80F system does not have provision for variance in the Motion Time Lag
from the default values shown in the Sensor Tab at this time.
Heading Correction (Optional)
Requires: DGPS or better, Distinct Object and 40m+ depth if using WASSP alone.
A note on heading correction was included in Commissioning Test 6. To determine
a more accurate heading correction between the heading sensor and the
transducer orientation we need high accuracy position sensors and corrected
sea-floor data. Approach a small distinct sea-floor feature so that the port side of
the swath covers the object. Next pass over the object so that the starboard side
of the swath crosses the same object in the opposite direction. It is important that
these two tracks are on exactly parallel heading lines. Use basic trigonometry to
calculate the required heading offset that will allow the object to remain stationary.
Redo the heading test to check that the heading offset was entered correctly.
tan(a) = -d/(2w) If object moves as above the sign is negated otherwise remove
the -ve sign from this equation
Enter the calculated value for a into the Heading Offset on the Sensor Tab.
www.wassp.com
w
a
d/2
Doc. P/N:
Version:
Issue Date:
d
WSP-009-002
V2.3
July 2014
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