| 摘要 |
PROBLEM TO BE SOLVED: To provide an OFDM (Orthogonal Frequency Division Multiplexing) demodulator capable of detecting correctly clock frequency errors. SOLUTION: The OFDM receiving system 1 is equipped with a clock frequency error calculating circuit 41 for calculating clock frequency errors between a received signal clock and an operating clock inside the system, and a guard correlation/peak detecting circuit 12 for determining autocorrelation of guard intervals to detect a peak timing of the correlation signal. The guard correlation/ peak detecting circuit 12 includes an automatic counter in its inside to output an automatic counter value at the peak timing to the clock frequency error calculating circuit 41, which calculates a time change rate of the input counter value using a plurality of time change rate detecting circuits that are set at different measurement intervals. The clock frequency error calculating circuit 41 makes the time change rate into a histogram, from which the clock frequency errors are calculated. COPYRIGHT: (C)2004,JPO&NCIPI
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