Unit installation

FS70 Trawl Sonar System
10 974-24007001/4.1
2.5 Key Features Setting
The following paragraph will explain some of the key features of
the FS 70 System.
2.5.1 Automatic Gain Control (AGC)
The AGC “Automatic Gain Control” algorithm increases the gain
during low acoustic returns and reduces the gain during strong
acoustic returns. The speed with which the gain is adjusted is
determined by the setting of the “RX Gain Response”
2.5.2 Reverberation Controlled Gain (RCG)
The RCG filter senses the noise level (reverberation, propeller
noise, etc.), and adjusts the gain of each of the received beams in
order to eliminate noise on the display. The strength of the filter can
be selected in the menu. With maximum strength selected, the RCG
will effectively reduce the bottom in shallow water, while variation
on the bottom will be displayed.
Note that scattered fish can be perceived as reverberation. The RCG
filter must be used with care if scattered schools are to be detected.
2.5.3 RX Gain Response and Type
The setting of the “RX Gain Response” determines the response of
the filter algorithm as selected by the “RX Gain Type”. For the
AGC, this setting determines the speed by which the gain is
adjusted. For the RCG, this setting determines the influence of the
previous ping average over the current ping. If set to “Slow” the
overall average is given by the sum of 20% current and 80% of
previous average. In “Medium” this ratio is 50% to 50%, and in
“Fast” the ratio is 80% to 20%.