PURPOSE: To provide an OFDM communication system capable of preventing erroneous frequency synchronization.
CONSTITUTION: In a demodulator for quadrature demodulating OFDM modulation signals using the codes of high autocorrelation along a frequency axis as reference signals for erroneous frequency synchronization prevention, transforming them to the signals of the frequency axis by an FFT processing and demultiplexing multiplexed signals at a prescribed timing, a frequency deviation is calculated from a rotation amount on the phase plane of FFT processing output in a frequency error detection circuit 27 and a carrier wave frequency for quadrature demodulation is controlled so as to turn the frequency deviation to '0.' Then, the reference signals for the erroneous frequency synchronization prevention are separated from the FFT processing output in a reference signal separation circuit 28, code correlation with the reference signals from a reference signal generation circuit 29 is detected in a correlation detection circuit 30 and whether or not synchronization is performed by a correct frequency is judged by a correlation peak position. The processing of frequency demapping is shifted corresponding to a judged result and thus, correct signals are surely demodulated.
AOKI TOSHIRO
SAWADA KENJI
