High Pulse Repetition Frequency Radar Early Warning Receiver.
Patent, Filed 4 Oct 89, patented 23 Apr 91,
DEPARTMENT OF THE NAVY WASHINGTON DC
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A ten db coupler receives an RF input signal and transmits an attenuated signal through a widebandnarrow band select switch to an RF amplifier. The signal is next processed through an RF amplitude detector. A comparator then receivers the signal and generates a pulse in response to signals exceeding a predetermined threshold. A pulse stretcher then eliminates excessive pulses due to noise or other signal oscillations that exceeded the comparators threshold. A circuit comprising a retriggerable monostable and an OR gate determine if the pulses received exceed a pulse repetition frequency threshold. A ripple counter than eliminates unwanted signals by resetting if a predetermined number is not reached in a specified time. A unique audio signal is then generated if the desired signal is detected. The output signal is audible even though the input signal is of a frequency above the normal hearing threshold. Also a visual signal is provided by a light emitting diode.
- Active and Passive Radar Detection and Equipment