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Pseudo tone-based symbol timing recovery and carrier tracking loop detectors for vestigial sideband receivers

  • US 8,559,563 B2
  • Filed: 01/14/2008
  • Issued: 10/15/2013
  • Est. Priority Date: 01/14/2008
  • Status: Expired due to Fees
First Claim
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1. Apparatus for use in a receiver, the apparatus comprising:

  • a carrier tracking loop for tracking a carrier in a received signal; and

    a symbol timing recovery loop for tracking symbol timing in the received signal;

    wherein the carrier tracking loop is driven as a function of a first pseudo tone and the symbol timing recovery loop is driven as a function of a second pseudo tone, the first and second pseudo-tones being developed from both edges of a staggered quadrature amplitude modulated version of the received signal such that the first pseudo tone is determined as a function of carrier offset excluding symbol timing offset, and the second pseudo tone is determined as a function of symbol timing offset excluding carrier offset;

    wherein the first and second pseudo-tones are provided by a detector that filters a lower edge and an upper edge of the staggered quadrature amplitude modulated version of the received signal;

    the detector further comprising;

    an upper filter for filtering the upper edge of the staggered quadrature amplitude modulated version of the received signal for providing a filtered upper signal;

    a lower filter for filtering the lower edge of the staggered quadrature amplitude modulated version of the received signal for providing a filtered lower signal;

    a squarer for squaring the filtered upper signal for providing a squared upper signal;

    a squarer for squaring the filtered lower signal for providing a squared lower signal;

    a multiplier for providing the first pseudo tone representing a product of the squared upper signal and the squared lower signal; and

    a multiplier for providing the second pseudo tone representing a product of the squared upper signal and a conjugate of the squared lower signal.

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