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Secondary channel signalling in a QAM data point constellation

  • US 4,630,287 A
  • Filed: 06/25/1985
  • Issued: 12/16/1986
  • Est. Priority Date: 12/28/1983
  • Status: Expired due to Term
First Claim
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1. A method of adding a secondary channel to a QAM signal mapped in the complex plane with data points assuming normal positions on concentric rings comprising the steps of:

  • (a) locating a pair of positions in the mapped complex plane (A and B) such that one-half the sum of the square of the distances to such positions from the origin (A2 +B2 /

         2) is no greater than the square of the distance from the origin to the position of the furthest mapped data point;

    (b) assigning a binary "1" to the existence of a data point at one of said pair of positions and a binary "0" to the existence of a date point at the other of said pair of positions;

    (c) shifting a single data point from a normal position to assume either of said pair of positions to define said secondary channel, the other data points being kept at their normal positions.

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