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23-1
23. COMMON REFERENCE SYSTEM
23.1 Installation of the System
Special attention of following topics is required to maintain the "Common Reference
System." The origin of the common reference system is the conning position on ves-
sel.
• The values of the center and conning positions depend on the size and geometry of
the ship.
• Offsets from the antenna position to the conning position of position sensors de-
pend on the location of the antennas of the position sensor.
• Offsets from the antenna position to the conning position of the radars depend on
the location of the radar antennas.
23.2 Accuracy of the System
Accuracy depends on the following conditions:
z Gyro error referenced to chart orientation
z Accuracy of EPFS
z Accuracy of radar performance and display (see the specifications at the back of
this manual).
z Accuracy of setting of CCRP (see section 2.33)
The following items must be properly adjusted to meet the above conditions:
z Timing (Tx timing of radar echo). The procedure for adjustment is shown in "Timing
Adjust" in the Installation Manual.
z Heading (Adjustment of radar echo heading). The procedure for adjustment is
shown in "Heading Alignment" in the Installation Manual.
z Radar ANT position (Center of radar image is the radar antenna position). Radar
antenna position is input in the [Common Installation Setting] menu.
z Conning position:
• The chart radar uses position data fed from a GPS navigator to calculate the lat-
itude and longitude position of the conning position.
• GPS antenna position and conning position are entered in the [Common Instal-
lation Setting] menu to calculate offset.
• The latitude and longitude position displayed at the top-right position on the
screen is the latitude and longitude position of the conning position.
• The chart datum used by the chart radar is recorded in geodetic datum WGS-84;
therefore, the geodetic datum setting on the GPS navigator must be WGS-84.
z Gyro data:
• Serial format gyro data is fed directly from a gyrocompass, thus adjustment of
the heading indication on the chart radar is not necessary.