1.3 Scanner unit
7
INT board (03P9322)
INT board mainly consists of CPU U4 that includes the RAM, ROM and analog ports, RS-422
interface U5, a motor drive circuit and a gain control signal generator.
CPU U4 receives control panel settings on the display unit through the RS422 interface U5. The
D/A converter U2 converts Gain, A/C RAIN, and tuning control signals from digital to analog.
A/C SEA and A/C RAIN circuit consisting of Q1, Q2 and Q3 outputs GAIN CONT signal to IF
board.
The CPU U4 controls the stepping motor drive circuit, Q4 to Q7 to keep the antenna rotation
speed constant.
The heading signal (HD) from the lead switch is mixed with the bearing pulse (BP) by Q9 to
Q11 and sent to the display unit.
The ship’s main is supplied to the power supply circuit on the MD board via INT board.
MD board generates +5 V, +12 V and -6 V for the use on INT board.
Fig.1-5 Block Diagram of INT Board (03P9322)
Display
unit
Step
motor
Waveform
generator
Interface
Mixer
Serial
Serial
Conv.
Reset
Ref. Osc.
Video signal
Filter
Ship’s mains
Buffer
Trigger
Bandwidth switch
Buffer
Q4, Q5
Q6, Q7
Pulsewidth signal
MD
Board
Lead
Switch
IF
Board
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