Simrad SP90
Beam
A narrow beam will always reach further than a wide beam. This
is because the transmitted power of the sonar is concentrated.
Nevertheless, you can easily “miss” a school of fish if you make
the beam too narrow. If the range is reduced, it is the common to
use a wider beam.
(CD015005A)
B
C
A
(A) = Wide beam, (B) = Normal beam, (C) = Narrow beam
Default setting on the SP90 sonar is
Normal
. This setting is
basically designed for longer ranges.
You may also try setting
Auto
. This setting will automatically
adjust the beam width depending on the current range.
Gain
You can adjust the gain in many different ways, but the most
important is the setting made by the
Gain
on the
Horizontal
and
Vertical
menus.
If you have too much gain, you will see a sonar picture with too
many echoes. This is because the large amplification presents all
kind of noise and reverberation that the sonar picks up. If the
gain is smaller the noise and reverberation will disappear, but if
it is too small the fish echoes may disappear as well. In most
cases you should try with a medium value. On the SP90 sonar,
the default value is set to
30
.
RCG
RCG means “Reverberation Controlled Gain”. This function
compare the strength from each echo, and then automatically
adjust the range and echo level in the sonar picture.
The RCG will remove unwanted echoes from the sea surface and
the bottom. If you select setting
Strong
the bottom echoes will
disappear altogether if the bottom is flat, while schools of fish
close to the bottom will be easier to see.
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Summary of Contents for Simrad SP90 Series
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