Raymarine hsb2 PLUS Series - Manual (Page 67)

Chapter 3: Standard Radar Operations 3-3
Ch
an
gi
ng
th
e
R
an
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Changing the Range
Figure 3-1: Changing the Radar Range
➤ Each time you press the RANGE key, the range changes to the next available
setting. The system will beep three times if no further range scale is available.
➤ To change the range quickly, press and hold the required arrow on the RANGE
key.
The range scale and range ring interval indicators, at the left-hand end of the
status bar, are updated whenever you change the range.
Determining Actual Radar Range
The actual maximum radar range is essentially line-of-sight, and is limited by
the height of the scanner and the height of the target as shown in Figure 3-1.
Table 3-2 lists some range examples:
Figure 3-2: Determining Radar Range
Note: The ranges shown in the table are theoretical maximum ranges. The ra-
dar horizon is greater than the optical horizon, but the radar can only detect
targets if a large enough target is above the radar horizon.
Table 3-2: Radar Range
Antenna Height (m) Target Height (m) Maximum Range (nm)
3 3 7.8
3 10 10.9
5 3 8.9
5 10 12.0
RANGE
D3939_1
Increases
the range scale
Decreases
the range scale
Selected
range scale Range ring
spacing
Status Bar
6nm
RR
1nm
343°T
RANGE
AUTO MAN
a
1
a
2
Earth
h
H
Cliff
Radar
D1643-2
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
)
81186_3.book Page 3 Thursday, August 22, 2002 8:23 AM