Patent ID: 7433296

Claim:
A method for processing a RF OFDM signal transmitted from an OFDM transmitter, comprising the steps of: receiving and converting the RF OFDM signal into an IF OFDM signal; converting the IF OFDM signal into a digital OFDM signal composed of an original sample sequence; detecting a transmission mode and guard interval length of the OFDM signal, comprising steps of: down-sampling the original sample sequence by a first, second, third and fourth factors to generate a first, second, third and fourth down-sampled sequence; delaying the original sample sequence by a first and second number of samples, and down-sampling the delayed sample sequences by the third factor to generate a fifth and sixth down-sampled sequence; applying a first, second and third correlation function to the first, second and fourth down-sampled sequence, and a fourth correlation function to the third, fifth and sixth down-sampled sequence, to derive a first, second, third, fourth, fifth and sixth correlation powers respectively; down-sampling the original sample sequence by a fifth, sixth, seventh and eighth factor to generate a seventh, eighth, ninth and tenth down-sampled sequence; delaying the original sample sequence by a third and fourth number of samples, and down-sampling the delayed sample sequences by the seventh factor to generate an eleventh and twelfth down-sampled sequence; applying the first, second and third correlation function to the seventh, eighth and ninth down-sampled sequence, and the fourth correlation function, to the tenth, eleventh and twelfth down-sampled sequence, to derive seventh, eighth, ninth, tenth, eleventh and twelfth correlation powers respectively; and determining the transmission mode and guard interval length by the first, second, third, seventh, eighth and ninth correlation powers, the maximum of the fourth, fifth and sixth correlation powers, and the maximum of the tent, eleventh and twelfth correlation powers; implementing digital processing of the OFDM signal in time domain and frequency domain; and implementing channel decoding and de-interleaving of the OFDM signal.