1. RADAR OPERATION
1-99
1.50 Reference
Position
The reference position for measurements (range, bearing, etc.) and markers
(heading line, stern mark, etc.) can be antenna position or consistent common
reference point (CCRP), which is a location on own ship to which all horizontal
measurements, for example range, bearing, relative course, relative speed,
closest point of approach (CPA) or time to closest point of approach (TCPA), are
normally referenced
.
To select reference position, right-click the REF POINT indication at the top of
the screen to select ANT or CCRP as applicable.
The position of the own ship marker changes according to reference position as
shown below. If the CCRP is positioned outside of the effective display area, the
bearing scale is indicated with the appropriate reduced detail.
X
CCRP position
X
ANT position
Radar antenna
position is at
center of display
Conning position is at
center of display
Range and bearing are measured and graphics are drawn according to
reference position as in the table below.
Markers, measurements and reference point
Reference point
Category Item
CCRP Antenna
position
EBL
VRM
Cursor
PI line
Range ring
Range and bearing
measurement
Drop mark
Range and
bearing
measured from
CCRP
Range and bearing
measured from
antenna position
Heading line
Stern mark
Beam line
Own ship vector
Graphics
Own ship track
Drawn from
CCRP
Drawn from
antenna position
