Patent ID: 6058121
Filing Date: 2000-05-02
Classification: H04L

Abstract:
A fine FFT window position recovering apparatus of an OFDM receiver for recovering a fast Fourier transform (FFT) window position using a symbol, including N effective data samples and G guards intervals, comprising:an analog-to-digital converter for converting an OFDM signal into a digital complex sample;a symbol start detector for detecting a starting portion of the symbol from digital complex samples output from the analog-digital converter;an FFT means for fast Fourier transforming the digital complex samples generated by the analog-to-digital converter based on the symbol start portion detected by the symbol start detector;a phase calculator for calculating phase variations between a complex value output from the FFT means and a known transmitted complex value;a zero-crossing counter for counting the number of zero-crossings of the phase variations generated by the phase calculator; andan FFT window controller for activating the FFT of the FFT means based on the symbol starting portion detected by the symbol start detector and for compensating for the sample error of the FFT of the FFT means by detecting the remaining FFT position error of a sample unit from the number of zero-crossings generated by the zero-crossing counter.