Navman F400, Installation And Operation Manual

Page: 14 / 48

14 NAVMAN Fishfinder User Manual
• If the desired mode is Top or Bottom then
use the
V
or the
^
key to adjust the limit
value to the desired level
• Press the key to accept the choice
and return to normal display
Gain function
The gain is a measure of ability to receive weak
signals. The higher the gain setting, the better
the unit is able to pick up weak return signals.
Deep water operation requires the gain to be
set to a higher value due to loss of signal in the
water.
There are two gain modes that can be selected,
Manual and Auto.
If Manual is selected then a gain setting from 0
to 15 must also be entered. This will be the
value of gain that is always used when displaying
information on the screen. A low gain number
may be suitable in shallow water but will need to
be increased for deep water operation
If Auto is selected then the gain will automatically
vary as the water depth changes. This feature
is particularly useful if you are fishing areas
where the depth changes suddenly. In Auto
mode, you can set the auto-gain value to provide
a consistent image of the bottom, regardless of
the bottom type. A low auto-gain setting will cause
a thin bottom image to be displayed. A high auto-
gain setting will result in a thick bottom image.
This adjustment is particularly useful with a weak
return signal from a muddy or silty bottom.
Normally, in these conditions the auto-gain will
increase the gain to a level that may make the
display appear too cluttered, making it difficult to
distinguish fish. In this situation the auto-gain
can be reduced to display a weak bottom image
but with improved fish images.
Setting the gain
• Press the
∗
key until the gain menu is
displayed
• Press either the key or the key to
move the pointer to the desired mode of
operation
• If the desired mode is Manual then use the
V
or the
^
key to adjust the value to the
desired level
• Press the key to accept the choice
and return to normal display mode
• If the desired mode is Auto then use the
V
or the
^
key to adjust the value to the
desired level. In Auto mode the gain will be
controlled to show the same bottom detail
irregardless of depth