Standard Horizon CP390i, Owner'S Manual

Page: 140 / 168

CP390i and CPF390i Page 141
17.10.1.0 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. 17.10.1.2).
17.10.1.1 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 mitigate the Surface Clutter and it progressively diminishes
to 0 at the selected STC depth.
17.10.1.2 Preset values table
OFF Short M i d Lo ng
STC De p th (Ft) 1 60 60 255
STC Le ng th 0 10 % 30 % 57 %
Figure 17.10.1.2 - STC Preset values table
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
Fish Finder to be able to see the bottom. In these cases change the RANGE MODE from
AUTO to MANUAL Range and manually adjust the depth range until the bottom echo
becomes visible on the Fish Finder display.
17.10.2 Surface Noise Filter
An automatic filter that attempts to dynamically remove Surface Clutter that causes the
screen to be filled up with strong return echoes just below the surface. It may seem that
the same functionality could be archived using on the STC control however there is main
difference between such control in fact the STC control impacts the capability to detect
and track the bottom and is not designed to cancel completely the surface noise, on the
other side the Surface Noise Filter attempts to cancel completely the surface noise but it
doesn’t affect the capability to detect and track the bottom.
Filter gradually attenuates surface noises. The Surface Noise Filter has 9 settings: OFF, 1,
..., 8. When it is set to OFF the Surface Noise is not cancelled. When it is set to 1 the Surface
Noise is attenuated from surface down to a depth of 5 Ft, increasing the Surface Noise
increases the depth in which the Surface Noise is attenuated as well as the attenuation level
increases; when the preset is set to 8 the attenuation is maximum and is applied from
surface level down to a depth of 255 Ft, as shown in the Surface Noise Filter Table reported
below: