Standard Horizon CPF300I, CPF180I owner manual STC Length, STC Strength

NOTE

When the Gain Mode option is set to Auto, the receivers Gain cannot be changed.

When the Gain Mode option is set to Manual, the Gain can be manually adjusted. When switching from Automatic to Manual Mode, the Gain + Offset value is copied into the Manual Gain setting of the receiver.

17.10.1STC (Sensitivity Time Control)

The purpose of this selection is to filter surface noise in the water.

The STC functions reduces or eliminates Surface Clutter signals by changing the Sensitivity of the receiver, decreasing it near the surface and gradually increasing it as the depth increases. Its default value is SHORT for the 200kHz frequency and MID for the 50KHz frequency. Such values are good in most conditions. However when navigating in very shallow waters it may be necessary to switch it to OFF, while in very deep waters with a lot of Surface Clutter it may be better to increase it to MID or LONG.

NOTE

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.

Figure 17.10.1 - STC - Surface Clutter

The STC can be changed from Short, Mid, Long and Custom.

17.10.1.0STC 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).

17.10.1.1STC 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.

CPF180i and CPF300i Page 121