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Detectability of emergency beacon

  • US 3,928,805 A
  • Filed: 09/20/1973
  • Issued: 12/23/1975
  • Est. Priority Date: 09/20/1973
  • Status: Expired due to Term
First Claim
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1. A method for increasing the range of an emergency locator radio transmitter beacon and for conserving transmitter power of the transmitter;

  • said method comprising;

    amplitude modulating a carrier waveform, having a frequency which is accurately controlled by a crystal oscillator, of the transmitter with a modulating rectangular waveform at a modulating frequency which is a precise submultiple of the accurately controlled carrier waveform frequency;

    transmitting the modulated waveform by radio waves;

    receiving said transmitted signal in a receiver means;

    demodulating said received signal; and

    cross-correlating said demodulated signal with the output of a reference signal source in said receiver means to thereby determine whether said demodulated signal is identical with said output, of said reference signal source;

    providing an indication signal when said demodulated signal is identical with said output of said reference signal source;

    characterized in that the transmitter is cyclically turned on and off to preserve power.

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