Raymarine hsb2 Series, Owner'S Handbook Manual

Page: 74 / 231

Chapter 3: Standard Radar Operations 3-9
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Sea Clutter Control
Radar returns from waves around your vessel can clutter the centre of the radar
picture (see
Figure 3-7 , making it difficult to detect real targets. Such sea
clutter usually appears as multiple echoes on the display at short range scales,
and the echoes are not repetitive or consistent in position. With high winds and
extreme conditions, echoes from sea clutter may cause dense background
clutter in the shape of an almost solid disc.
Figure 3-7: Sea Clutter
The
SEA
control reduces the gain level in the areas near your vessel, extending
up to 3 to 5nm depending on the wave and sea conditions. This has the effect of
reducing the sea returns to intermittent small dots, while small targets are still
visible. Gain levels further from your vessel remain unchanged.
You can use the gain and Sea control to help minimize the effects of side lobes
(see
Identifying False Echo Returns on page 3-5 ).
Note: On short range scales, do not set the Sea control so high that all clutter
is removed, since this could stop you seeing echoes from close targets.
Tuning the Receiver
The
TUNE
control is used to fine tune the receiver in the scanner for maximum
target returns on the display. In Auto mode, the radar tunes itself automatically
on all range scales.
We recommend that you leave the
TUNE TUNE TUNE TUNE
control in Auto
mode.
If you do set the
TUNE
control to Manual, you will need to adjust it about 10
minutes after you have turned on the radar, since the required setting changes
once the magnetron has warmed up.
You should adjust the control to obtain the maximum signal strength, as
indicated in the 8-step bar above the slider. If you cannot tune the radar
successfully, refer to
Section 7.6 for information on the Tune Preset function.
SEA
MANUAL
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TUNE
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