7.2 Antenna Unit
7-25
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.
Fig. 7.2.19 Schematic Diagram of Automatic STC Processing-1
A/D
STC DETECT
STC CONT
STC CONT
Average
within sector
(Sweep)
Average the
each same
sector
(Scan)
STC Curve
Processing
STC Gain
Off-set
IF board
RFC FPGA
RFC CPU
A/C SEA VR
- Model
- STC Condition
- SEA Condition
- Default ANT height
- Near/Mid/Far STC curve
10 sec
Range
Sweep
Average of each range
A sector
Average of each range
A+1 sector
RFC board