Reference Manual Part 2

141 Chapter 11: Radar
Gain presets
There are four preset gain modes to give you the best picture in dif-
ferent circumstances.
Harbor is the default mode. This setting takes account of land clut-
ter so that smaller targets, like navigation buoys, are not lost.
Coastal accounts for the slightly higher levels of sea clutter you
might encounter out of harbor and adjusts the radar display
accordingly.
Offshore automatically adjusts for high levels of sea clutter.
Buoy is a special mode to enhance the detection of small objects
like mooring buoys. It is useful at ranges up to 3/4 nm.
Manually adjusting gain
The gain function makes the radar picture clearer by changing the
sensitivity of radar reception.
• For long ranges select a sensitivity level that gives a slight
speckle in the background. Setting the gain too low can cause
weak or small targets to disappear, however.
• For shorter ranges reduce the gain slightly to reduce speckle
and improve target definition.
Note: If you control gain manually, check it each time you change
the range scale.
To manually adjust gain settings
1. Press the GAIN softkey.
2. Press the ADJUST softkey for the preset mode you are in.
3. Select manual on the GAIN softkey.
The changes you make are applied to both the active window and
any other radar windows displaying this preset. Gain setting
changes are kept at system power-off.
Rain clutter
Radar detects echoes from rain or snow. The strength of these ech-
oes depends upon the altitude, range, density and size of the snow
flakes or rain droplets and appear on screen as countless small
echoes continuously changing size, intensity and position.
Turning the RAIN clutter function on suppresses the bulk effect of
rain returns from around your boat, so that recognizing other
objects is easier.
Sea clutter
Radar echoes from waves around your boat can clutter the centre
of the radar picture, making it difficult to detect real targets (see
page 131).
Adjusting the sea mode will reduce this clutter for up to 5 nautical
miles (depending on wave and sea conditions) from your boat. This
reduces sea echoes to intermittent small dots, while small targets
remain visible and persistent. Gain levels further from your boat
remain unchanged.
Super HD adjustments
You can generally use the default AUTO settings for best results,
but two manual controls allow you to explore Super HD’s
capabilities.
Antenna boost
This scales the effective antenna size. At zero, the effective
antenna size matches its actual size. At 95, the effective antenna
size is doubled.
Increasing effective antenna size has the effect of separating tar-
gets that appear merged at lower settings.