Patent ID: 6192056
Filing Date: 2001-02-20
Classification: H04L

Abstract:
A demodulating apparatus having time synchronizing signal generator means for receiving a digital orthogonal frequency division multiplex modulated signal in which an information signal modulates a plurality of carriers having respective frequency components in an orthogonal relationship with each other and for generating a time synchronizing signal synchronized with a symbol forming each frame of said digital orthogonal frequency division multiplex modulated signal, frame synchronizing signal generator means for generating a frame synchronizing signal synchronized with each frame of said digital orthogonal frequency division multiplex modulated signal, and fast Fourier transform means for receiving said digital orthogonal frequency division multiplex modulated signal, said frame synchronizing signal, and said time synchronizing signal and for fast Fourier transforming the digital orthogonal frequency division multiplex modulated signal, so that a demodulated digital information signal may be obtained from said fast Fourier transform means, comprising:correlation detector means for detecting a correlation between a guard section of said symbol of said digital orthogonal frequency division multiplex modulated signal and a section having a correlation with said guard section in an effective symbol of said symbol;section integrator means for section integrating a detected output of said correlation detector means with respect to said guard section;peak detector means for detecting a peak of a triangular wave signal output from said section integrator means; andframe timing signal producing means for producing a frame timing signal of a predetermined frame of each of said frames based on a peak detecting signal from said peak detector means,wherein said frame synchronizing signal generator means is synchronized by a frame timing signal from said frame timing signal producing means.