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Demodulation using a time domain guard interval with an overlapped transform

  • US 5,886,749 A
  • Filed: 01/28/1997
  • Issued: 03/23/1999
  • Est. Priority Date: 12/13/1996
  • Status: Expired due to Term
First Claim
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1. A method for signal demodulation comprising the steps of:

  • providing a radio frequency (RF) time domain signal on a transmission channel, the RF signal comprising a band-limited data signal modulated on an RF carrier, the data signal comprising a plurality of transmission blocks of data;

    providing a time domain guard interval attached to each transmission block in the transmitted signal;

    demodulating the RF signal to baseband as an in-phase (I) data signal and a quadrature (Q) data signal;

    capturing a first block of I data;

    capturing a first block of Q data;

    performing a complex discrete Fourier transform on the captured first I and Q data blocks;

    determining an inverse channel response for the transmission channel;

    multiplying the inverse channel response by the complex discrete Fourier transform of the guard-interval protected first I and Q data blocks to generate a frequency domain product signal;

    performing an inverse Fourier transform on the product of the multiplying step to generate a first equalized time domain signal; and

    discarding a first portion of the first equalized time domain signal while retaining a second portion of the first equalized signal.

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