Technical description – Kannad Marine Rescuer 2 SART User Manual

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8. Technical description

A single switched antenna is used for both receive and transmit functions; the switch
normally connects the antenna to the receiver circuit. In the standby state only the
receiver portion of the SART is powered to reduce battery consumption to a minimum.
In this condition the indicator circuit causes the LED to flash once every two seconds.

On receipt of a radar pulse the video amplifier and detector circuit causes the rest of
the circuitry to become active and the unit switches to transmit mode. In this condition
the indicator circuit causes the LED to remain steady and the buzzer to sound every
two seconds.

The detection of a radar pulse causes the switch to connect the antenna to the
transmitter circuit. The output stage is fed by a Voltage Controlled Oscillator (VCO),
whose frequency is determined by a sweep generator. When triggered by the detector
the sweep generator turns on the VCO and causes it to produce exactly 12 forward
and reverse frequency sweeps before shutting down again.

If no radar pulses are detected for a period of 15 seconds the unit reverts to standby