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Duobinary coding and modulation technique for optical communication systems

  • US 5,892,858 A
  • Filed: 03/27/1997
  • Issued: 04/06/1999
  • Est. Priority Date: 03/27/1997
  • Status: Expired due to Term
First Claim
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1. A method for encoding a binary input sequence x(n,d) to obtain a duobinary output sequence y(+d,n,-d), comprising the steps of:

  • providing a first logical level "n" for a bit yk of said duobinary output sequence y(+d,n,-d) when a corresponding bit xk of said binary input sequence x(n,d) has said first logic level "n";

    switching a bit yk of said duobinary output sequence y(+d,n,-d) from said first level "n" to alternatively assume one of a second "+d" and a third "-d" logical level, whenever a succession xk-1, xk of bits in said input sequence x(n,d) comprises a change from said first logical level "n" to said second logical level "d"; and

    maintaining the logical level of a bit yk as one of said second +d" and said third "-d" logical level, whenever a corresponding bit xk maintains said second logical level "d" and whenever a succession xk-1, xk of bits said input sequence x(n,d) comprises a change from said second logical level "n" to said first logical level "d".

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