A signal transmitting apparatus using orthogonal frequency division multiplexing includes an inverse fast Fourier transform circuit for converting a digital information signal into a first multi-value QAM modulation signal. A guard interval setting circuit is operative for periodically generating a guard...http://www.google.com/patents/US5657313?utm_source=gb-gplus-sharePatent US5657313 - Signal transmitting apparatus and signal receiving apparatus using orthogonal frequency division multiplexing
