Furuno FAR-2107 Series Service Manual page 430

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7.2.8 Automatic STC (SEA AUTO)

This signal processing is performed on the RFC board. This setting is switched by

ON/OFF of the [AUTO/MANU SEA] box. The automatic STC is a function to

automatically control the level of STC waveform corresponding to receiving levels. It

calculates an optimum sea clutter attenuation curve corresponding to signal levels of a

near range and creates STC voltage. Parameters to determine the curve are Model, STC

Condition SEA Condition, Default ANT height, and Near/Mid/Far STC curve in the

INITIALIZE menu. See page.4-15.

STC CONT signals inputted into the IF board are outputted by setting the STC bias so

as to give an optimum picture when the STC is set to AUTO and the STC control knob

is se at 50 %.

The figure below is the block diagram of the automatic STC processing. For the

receiving signal level, one rotation of the antenna is divided into 32 sectors, the

receiving level is averaged for each sector, and each sector divided into 32 is averaged

for 10 seconds, and the STC is created from the data.

Average of each range

Average of each range

Fig. 7.2.19 Schematic Diagram of Automatic STC Processing-1

within sector

- STC Condition

- SEA Condition

- Default ANT height

- Near/Mid/Far STC curve

7.2 Antenna Unit