×

Non-coherent direct sequence spread spectrum receiver for detecting bit/symbol chip sequences using threshold comparisons of chip sequence correlations

  • US 5,687,190 A
  • Filed: 10/20/1995
  • Issued: 11/11/1997
  • Est. Priority Date: 10/20/1995
  • Status: Expired due to Fees
First Claim
Patent Images

1. A method for recovering a digital signal comprising a sequence of bits having a first and second state from a direct sequence spread spectrum phase shift keyed signal wherein each bit in the first state is substituted by one of a first set of chip sequences and each bit in the second state substituted by a one of a second set of chip sequences, the method comprising the steps of:

  • demodulating the direct sequence spread spectrum signal to form an in-phase baseband signal and a quadrature-phase baseband signal;

    correlating the in-phase baseband signal with each chip sequence of the first set of chip sequences to generate a first set of correlation values;

    correlating the in-phase baseband signal with each chip sequence of the second set of chip sequences to generate a second set of correlation values;

    correlating the quadrature-phase baseband signal with each chip sequence of the first set of chip sequences to generate a third set of correlation values;

    correlating the quadrature-phase baseband signal with each chip sequence of the second set of chip sequences to generate a fourth set of correlation values;

    comparing each correlation value to a corresponding threshold value;

    responsive to any of the first and third correlation values being greater than the corresponding threshold values, indicating a first bit state detection; and

    responsive to any of the second and fourth correlation values being greater than the corresponding threshold values, indicating a second bit state detection.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×