JRC JMA-5212-4, Service Manual

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2-10
Figure 2.3 shows the functional system diagram of the display system for this equipment.
A. Start of the equipment
When the power switch on the operation unit is turned on, the power circuit CBD-1702A
is started, and generated voltages are supplied to the radar processing circuit CDC-1350.
Then, the CPU in each control circuit starts up and performs initialization.
When the power is turned on, the local CPU and the CPU in the AIS processing circuit
CDC-1353, and the CPU in the operation circuit CCK-979 are released from the reset state,
and they initialize the hardware connected to them and wait for a control command from the
main CPU in the radar processing circuit CDC-1350.
When the main CPU is released from the reset state, it initializes the whole system after
the radar plotting/display function. The main CPU sends an initialization command to the
local CPU so as to initialize the radar signal setting, and at the same time it sends a
communication initialization command to the CPU in the operation unit so as to initialize the
operation function. The main CPU also starts the DSP by writing programs into memory in
the DSP of the ARPA processing circuit, and issues an initialization command to the CPU in
the AIS processing unit so as to initialize the AIS processing circuit.
After that, the main CPU sets the internal condition according to sensor data which is
input through the communication lines of NSK unit, GPS, etc., and it issues an initialization
command to the scanner unit via the communication line so as to initialize the scanner.
System initialization is complete when the scanner has been initialized.
B. Functions of the circuits
The NSK unit NCT-4106A (option) processes gyro signals of synchro or step type,
calculates true bearing values, and periodically transmits true bearing data to the radar
processing circuit through serial communication. As long as gyro signals are supplied,
power is supplied to the NSK unit even when the display system is turned off, and the CPU
is active. Thus, the NSK unit can continue to calculate true bearing values even when the
display system is turned off.
The CPU in the operation circuit detects the operating conditions of switches and dials on
the operation panel, and transmits the operation data to the main CPU through the
communication line.