Raymarine E90W, User Reference Handbook

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Powering the radar scanner on and off
In the radar application:
1. Press the POWER button on your multifunction display.
2. Using the relevant softkeys, select the operating mode for the
radar scanner.
9.4 Radar range and image quality
Maximum radar range
The usable range of the radar is limited by factors such as the
height of the scanner, and height of the target.
Maximum radar range is essentially line-of-sight, so is limited by
the height of the scanner and the height of the target as illustrated
below:
a
1
a
2
Earth
h
H
Cliff
Radar
D1643-3
Rmax
Rmax = 2.23 ( h + H )
Rmax
h
H
maximum radar range
radar antenna height
target height in nautical miles
in metres
in metres
Rmax = radar horizon of antenna (
a
1
) + radar horizon of target (
a
2
)
The table below shows typical maximum radar ranges for various
radar antenna heights and target heights. Remember that although
the radar horizon is greater than the optical horizon, the radar
can only detect targets if a large enough target is above the radar
horizon.
Antenna height
(meters) Target height
(meters) Maximum range
(Nautical miles)
3 3 7.7
3 10 10.9
5 3 8.8
5 10 12
118 E-Series Widescreen User reference