JMA-5300MkIIsm

INDEX > 2.System Configulation > 2.3 Function System Diagram
A transmission timing pulse is generated in the interface circuit, which is input to
the modulator switching circuit for high voltage switching. The pulse transformer
further increases the voltage of the high-voltage pulse, and the high voltage is
applied to the magnetron. In this way, pulse-modulated microwaves are obtained.
The pulse width and the pulse-repetition frequency are specified by means of
control commands from the display unit.
The radar wave passes through a duplexer circuit that uses a circulator and then
through a rotary joint, before being transmitted into the air from the antenna.
A signal reflected from a target is input from the antenna to the receiving block
using the duplexer function. The received signal is amplified before being
converted to the IF frequency, after which logarithmic detection is performed and
the signal becomes a radar video signal. If the receiving tuning function is set to
the auto mode, the interface circuit processes the received signal and
automatically controls the tuning voltage so as to match the optimum local
frequency.
When the interface circuit turns on the scanner unit relay, DC power is supplied to
the motor driver circuit and the antenna motor rotates. If the safety switch is off,
the power supplied to the motor driver is forcibly shut off, stopping the rotation of
the antenna motor. The beam azimuth of the antenna is detected by the encoder.
When the radiator is subjected to external force of wind (corresponding wind
speed is greater than 51.5m/s) that exceed the ability to drive the scanner unit, the
scanner unit stop to drive the motor. Because a built-in overload protection circuit
is activated. If the scanner unit rotates by the wind in a counterclockwise
direction, the TXRX[Reverse] alarm will be appeared, and stop to transmit. If the
scanner unit rotates by the wind in a clockwise direction, the scanner unit stop to
drive the motor. Therefore the TXRX[AZI] alarm will be appeared when the wind
is calm down.
When the corresponding wind speed is less than or equal to 51.5m/s, the break
circuit (in the scanner unit) can reduce the scanner rotation speed to 11rpm less
than, therefore the radar can transmit normally.
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