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Method and system for pulse interval modulation

  • US 5,026,156 A
  • Filed: 07/24/1972
  • Issued: 06/25/1991
  • Est. Priority Date: 07/24/1972
  • Status: Expired due to Term
First Claim
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1. A reflected wave energy system comprising:

  • means for transmitting a psuedo-random, cyclically repetitive code including a series of pulses of wave energy, the spacing of the pulses of said code defining a plurality of sequential pairs of time intervals, each pair of time intervals being unique within one cycle of said code;

    means for receiving pulses of wave energy;

    a first shift register;

    means responsive to said pulse receiving means for clocking pulses into a first serial shift register at a first predetermined rate;

    means for generating a series of pulses defining said psuedo-random, cyclically repetitive code;

    a second shift register;

    means responsive to said pulse generating means for clocking pulses into said second shift register at a second predetermined rate higher than said first predetermined rate;

    means for comparing the signal levels of corresponding stages of said first and second shift registers; and

    ,means responsive to said comparison means for generating a specific signal.

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