Patent ID: 7099381

Claim:
A de-spreading method in which a correlation operation between a first selected signals time-sequentially inputted and a predetermined code is performed so that data suitable for the code is extracted from the input signals, the de-spreading method comprising: generating a delayed signal by delaying an input signal relatively with respect to a code; selecting the input signal or the delayed signal in one chip on a time division basis in accordance with a first correlation operation that is a correlation operation between an input signal in a predetermined receive timing and a synchronization detecting code, a second correlation operation that is a correlation operation between an a second selected signal in a late timing relatively more delayed than the receive timing with respect to the synchronization detecting code and the synchronization detecting code, a third correlation operation that is a correlation operation between a third selected signal in an early timing relatively more advanced than the receive timing with respect to the synchronization detecting code and the synchronization detecting code, and a fourth correlation operation that is a correlation operation between a fourth selected signal in the receive timing and a data extracting code, and repeating the selection over a plurality of chips; performing the first to the fourth correlation operations, wherein first to fourth unit operations, which are arithmetic operations in a chip for the first to the third correlation operations between the input signal or the delayed signal selected in accordance with the first to the fourth correlation operations and the synchronization detecting code, and are arithmetic operations in a chip for the fourth correlation operation between the input signal or the delayed signal and the data extracting code, are performed on a time division basis in one chip and are performed repeatedly over a plurality of chips, and results of the arithmetic operations of the first to the fourth unit operations, which are obtained through the repetition, are accumulated on the first to the fourth unit operations in a plurality of continuous chips; and setting the timing of the largest correlation value among the receive timing, the late timing and the early timing, as the subsequent receive timing in accordance with the results of the first to the third correlation operations, and extracting data suitable for the data extracting code.