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Northstar M121/M84 Installation and Operation Manual62
18 Radar
Radar is the Radio Detection And Ranging
system. Radar functions require an optional
Northstar radar system to be installed. Three
radar systems are available; 2 kW, 4 kW, or
6 kW.
When the radar is operating, the scanner
transmits powerful microwave radio pulses
which are reflected back from any solid objects
such as land masses or other boats. These
objects are called targets and are shown on the
radar window.
The scanner rotates through 360° so the radar
window shows all of the area around your boat
within the range of the scanner, producing a
map-like display called the PPI (Plan Position
Indicator).
Typically, your boat is in the centre of the
radar window with concentric range rings
surrounding it. The range rings help you to
quickly estimate the distance to various targets.
If you prefer to view the radar overlaid on the
chart screen see section 3-2-7.
18-1 Radar window
The radar window shows:
A Distance between each range ring (in this
example, 1/8 nautical mile)
B Range of radar (in this example, shown in
large digits)
C Radar rotation (in this example, North Up)
D Radar motion mode (in this example,
Relative Mode)
E Cursor
F Distance and bearing to the cursor position
G Compass ring
H Range ring
I North line (blue)
J Heading line (white)
K The bearing (in Relative, True, or Magnetic
mode)
L Echo Expansion setting
M Interference Rejection setting
I
J
H
M
L
K
D
C
B
A
G
E
F