Abstract: A data input means has a data storing unit, transfer control unit, and exclusive wiring. The data input means divides a plurality of data strings into a plurality of groups on a frequency axis. Each of the plurality of data strings includes frequency components which is Fourier-transformed. The data input means inputs the data strings to a correlation operation unit which is a computing element every divided groups which correspond with each other. The correlation operation unit performs the correlation operation every divided groups which correspond with each other in a plurality of data strings.

Abstract: An FFT operation apparatus performs the real number FFT operation in real time for an extremely large number of data using a cache memory. The cache memory stores a part of data to be operated through the real number FFT. An FFT operation unit performs the real number FFT operation for the data stored in the cache memory. The FFT operation unit performs the data transfer between the cache memory and the external memory at least once after any of the stages in the first butterfly operation of multiple stages to read data to be required in subsequent butterfly operation in the first butterfly operation and the second butterfly operation for acquiring the transform results into the cache memory, performs the subsequent butterfly operation using the read data, and performs the second butterfly operation directly using the data stored in the cache memory after the first butterfly operation.