Standard Horizon FF525 Installation And Operation Manual page 31

In some situations it may be necessary to adjust the STC so the sounder can read through the
surface noise and show the bottom. One indication that the STC needs to be changed is when the
display intermittently changes the depth from the correct depth to a very shallow depth.
The STC can be changed from Short, Mid, Long and Custom.
5.5.1.0 STC Length
This is the depth range which the STC operates. In custom mode it can be varied from 0Ft
to 1000Ft (60Ft or 255Ft on previous software versions). In preset mode it's value is
reported in the following table (See Par. 5.5.1.2).
5.5.1.1 STC Strength
It is the starting attenuation value of the STC. It acts by attenuating the Gain of the given
percentage value. In custom mode it can be varied from 0% to 100%. The STC effect is
maximum near the surface, to eliminate the Surface Clutter and it progressively diminishes
to 0 at the selected STC depth.
5.5.1.2 Preset values table
STC Depth (Ft)
STC Length
If in VERY SHALLOW WATER the Fish Finder display is showing a bottom or digital
readout deeper than the actual depth this situation may occur if STC is set to LONG or
MID when the bottom is shallow. This issue may be resolved by adjusting the STC value
to SHORT or even to OFF in very shallow waters.
If in DEEP WATER the Fish Finder display is showing a very shallow bottom or digital
readout this may happen because in conditions of strong Surface Clutter the Fish Finder
may erroneously look on to the Surface Clutter. To solve this situation try to increase the
STC to LONG or to CUSTOM increasing the STC length and strength.
If in DEEP WATER the Fish Finder doesn't see the bottom, this may happen because the
bottom is out of range or is very near to the maximum depth that can be tracked by the
Fish Finder. In the latter case this may happen if the bottom composition is soft as mud,
if the sea conditions are bad, there are thermoclines or the water is full of suspended
materials (silt, plankton). All these factors may affect considerably the performance of the
FF525
NOTE
Figure 5.5.1 - STC - Surface Clutter
OFF Short
1 60
0 10%
Figure 5.5.1.2 - STC Preset values table
Mid Long
60 255
30% 57%
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