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

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NAVIKNOT 600 SD 056353/J
Doppler Transducer Calibration 7-1
Chapter 7: Doppler Transducer Calibration
Once the NAVIKNOT 600 SD system has been installed and the basic
configuration carried out, a calibration of the Doppler transducer must
be proceeded. During the calibration procedure, the speed measures of
the water passing the transducer, are calibrated to reflect the speed
through water and distance through water values of the ship to meet the
specified accuracies.
7.1 Doppler Transducer Calibration
To minimize the deviation between the vessel’s actual water speed and
the speed displayed and transmitted, the NAVIKNOT 600 SD stores
transducer-specific calibration data in a so-called calibration table.
The calibration table holds up to 21 entries (“calibration points”), each
of which relates an uncalibrated raw value to a corresponding true water
speed value. The entries holding the lowest and highest uncalibrated
values determine the range over which calibration is effective.
The effects of setting calibration points (i.e. adding entries to the calibra-
tion table) at different states of calibration are illustrated in figure 7-1 on
page 7-2.
Note To calibrate speeds astern, at least one calibration point with a negative
uncalibrated speed value must be stored. Otherwise, calibration is effec-
tive for speeds ahead only.