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Phase error detecting method and phase tracking loop circuit

  • US 5,796,786 A
  • Filed: 10/18/1996
  • Issued: 08/18/1998
  • Est. Priority Date: 10/18/1995
  • Status: Expired due to Term
First Claim
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1. A phase error detecting method in a communication device of a digital VSB modulation system, comprising the steps of:

  • (a) recovering Q-channel data by digitally filtering transmitted I-channel data;

    (b) correcting the phases of said I-channel data and said Q-channel data by a predetermined weighted phase error value to produce phase-corrected I-channel data and phase corrected Q-channel data;

    (c) deciding an I-channel level value closest to the phase-corrected I-channel data among predetermined I-channel level values;

    (d) obtaining a phase error value by subtracting the decided I-channel level value from said phase-corrected I-channel data, and multiplying the subtracted result by the sign of said phase-corrected Q-channel data; and

    (e) multiplying said phase error value by a weight value according to a predetermined weighting function W(I) to produce a weighted phase error value, and feeding back said weighted phase error value for use in step (b).

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