Sperry Marine NAVIKNOT 600 SD, Operation, Installation And Service Manual

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056353/J NAVIKNOT 600 SD
7-6 Doppler Transducer Calibration
Calibration by Trial Runs
Calibration by trial runs is the recommended method to calibrate the
Doppler transducer in the NAVIKNOT 600 SD. system. The procedure
resembles the familiar “milepost run”, but permits any known distance
to be taken as the length of a run.
The known distance may be given by the distance between sidebearings
to prominent landmarks. The regular procedure in this case is to start
and stop the run clock exactly at the points in time when the landmarks
are sighted athwartships.
However, as the NAVIKNOT 600 SD obtains the vessel’s current position
from the satellite PCB, it is equally acceptable to start the run clock at a
given point in time and to stop it as soon as a distance of at least one
mile has been traversed.
Generally, for each correction value to be determined, a two way trial
run should be carried out, i.e. the same known distance “l” should be
traversed in opposite directions (runs A and B). This will make the
effects of drift due to wind and current cancel out each other automati-
cally. Only when no wind and current are present, a one way trial run
may be carried out.
The first two or one way trial run should be carried out at maximum sea
speed, to define the upper limit of the calibrated range. Additional trial
runs may be carried out later at lower speeds to improve the accuracy
within the calibrated range.
Figure 7-2:
Calibration
by trial runs
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approach to run A or one-way run
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start of run A or one-way run
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end of run A or one-way run
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approach to run B
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start of run B
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end of run B
known distance “l”