Radio LAN station with improved frame delimiter detection in a spread spectrum environment

  • US 5,151,920 A
  • Filed: 09/10/1991
  • Issued: 09/29/1992
  • Est. Priority Date: 09/10/1991
  • Status: Expired due to Term
First Claim
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1. A radio LAN station for receiving information frames including start and end delimiters, said start and end delimiters including data symbols and non-data symbols, said data symbols and non-data symbols being transmitted via a spread spectrum signal and being spread via first and second spreading codes, respectively, said station comprising:

  • analog to digital conversion means adapted to provide a digital representation of a received spread spectrum signal;

    first correlating means, coupled to said analog to digital conversion means, for correlating a digital representation of said spread spectrum signal against said first spreading code to produce a rectangular representation of said data symbols;

    second correlating means, coupled to said analog to digital conversion means, for correlating a digital representation of said spread spectrum signal against said second spreading code to produce a rectangular representation of said non-data symbols;

    first converting means, coupled to said first correlating means, for converting said rectangular representation of said data symbols into a polar representation of said data symbols to produce a vector length Z representative thereof;

    second converting means, coupled to said second correlating means, for converting said rectangular representation of said non-data symbols into a polar representation of said non-data symbols to produce a vector length Z'"'"' representative thereof; and

    means for determining that a symbol is a data symbol if Z--Z'"'"' is greater than or equal to a constant A, or that a symbol is a non-data symbol if Z--Z1 is less than said constant A, such that the data and non-data symbols representing said start and end delimiters are detected.

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