Raymarine A65, Руководство по эксплуатации

Страница: 239 / 390

16.5 Radar context menu
The radar application includes a context menu which
provides positional data and menu items.
The context menu provides the following positional
data for the cursor location in relation to your vessel:
• Latitude
• Longitude
• Range
• Bearing
The context menu also provide the following menu
items:
• Acquire Target
• Place VRM/EBL
• Place Waypoint At Cursor
• Slew thermal camera (Only available when
thermal camera is connected and operating.)
Accessing the context menu
1. Non-touchscreen and HybridTouch displays:
i. Move the cursor over the area or object and
pressing the
Ok button.
2. HybridTouch and Touch only displays:
i. Select and hold on an area or object, or
ii. With the Chart Call-out displayed select the
Call-out box.
16.6 Radar range and image quality
Radar image quality
A number of factors can affect the quality of a radar
image, including echoes, sea clutter, and other
interference.
Not all radar echoes are produced by valid targets.
Spurious or missing echoes may be caused by:
• Side lobes.
• Indirect echoes.
• Multiple echoes.
• Blind sectors.
• Sea, rain, or snow clutter.
• Interference.
Through observation, practice, and experience, you
can generally detect these conditions very quickly
and use the radar controls to minimize them.
Side Lobes
Side lobe patterns are produced by small amounts of
energy from the transmitted pulses that are radiated
outside the narrow main beam. The effects of side
lobes are most noticeable with targets at short
ranges (normally below 3 nm), and in particular with
larger objects. Side lobe echoes form either arcs on
the radar screen similar to range rings, or a series of
echoes forming a broken arc.
D1638-5
1
2 2
3
4
5
6
6
Item Description
1 Main lobe
2 Side lobes
3 Antenna
4 Arc
5 True echo
6 Side echoes
Indirect Echoes
There are several types of indirect echoes or ghost
images. These sometimes have the appearance of
true echoes, but in general they are intermittent and
poorly defined.
Radar application
239