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Ofdm demodulation apparatus

  • US 20050147186A1
  • Filed: 12/18/2003
  • Published: 07/07/2005
  • Est. Priority Date: 12/27/2002
  • Status: Abandoned Application
First Claim
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1. An OFDM demodulator for demodulating an orthogonal frequency division multiplex (OFDM) signal using, as a unit of transmission, a transmission symbol including an effective symbol generated by making time division of an information series and modulating the information into a plurality of sub-carriers and a guard interval generated by copying the signal waveform of a part of the effective symbol, the apparatus comprising:

  • a reference time generating circuit for generating a reference time on the basis of a reference clock;

    a guard correlation peak time detecting circuit for detecting a timing in which the autocorrelation of the guard interval portion of the OFDM signal attains to its peak and generating the timing (peak time) synchronous with the reference time; and

    a symbol-boundary time calculating circuit for calculating, on the basis of the peak time, a symbol-boundary time that is a boundary time of the transmission symbol synchronous with the reference time, the symbol-boundary time calculating circuit including;

    a symbol-boundary time generator for generating a symbol-boundary time synchronous with the reference time;

    a time difference detector for detecting a difference between the symbol-boundary time and peak time; and

    an averaging unit for calculating a mean time difference by low-pass filtering of the time difference, the symbol-boundary time generator calculating the symbol-boundary time on the basis of the mean time difference.

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