Raymarine hsb2 PLUS Series GPS Receiver User Manual


 
Chapter 3: Standard Radar Operations 3-3
Changing the Range
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 rangequickly, pressand hold therequiredarrow 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 actualmaximum radar range is essentiallyline-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 thetable aretheoretical maximum ranges. Thera-
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
R
max
R
max
= 2.23 ( h + H )
R
max
h
H
maximum radar range
radar antenna height
target height
in nautical miles
in metres
in metres
R
max
= radar horizon of antenna (
a
1
) + radar horizon of target (a
2
)
81186_3.book Page 3 Thursday, August 22, 2002 8:23 AM