Patent ID: 8005157

Claim:
A correlation calculation unit comprising: four arithmetic units each including a first differential arithmetic section calculating a difference between an OFDM signal and a first delay signal delayed from the OFDM signal by a preset time and having a phase changed from the OFDM signal by a preset phase variation, the OFDM signal representing an orthogonal frequency division multiplexing signal, and one symbol interval of the OFDM signal including an effective symbol interval and a guard interval obtained by copying a part of a signal in the effective symbol interval; a second differential arithmetic section calculating a difference between a second delay signal delayed from the OFDM signal by a length of the effective symbol interval and a third delay signal further delayed from the second delay signal by the preset time and having a phase changed from the second delay signal by the preset phase variation; and a multiplication section multiplying an arithmetic result of the first differential arithmetic section by an arithmetic result of the second differential arithmetic section, wherein the four arithmetic units respectively differ in the phase variation by π/2; four polarity conversion units provided to correspond to the four arithmetic units, and converting arithmetic results of the multiplication sections of the corresponding arithmetic units into polarity signals indicating polarities of the arithmetic results, respectively; four integrating units provided to correspond to the four polarity conversion units, and integrating the polarity signals obtained by the corresponding polarity conversion units, respectively; and an addition unit adding up integrated results of the four integrating units, and outputting an addition result as a correlation signal indicating a correlation between the OFDM signal and the second delay signal.