Fast Fourier transform device, fast Fourier transform method, and recording medium storing fast Fourier transform program

1. A digital filter device, comprising:

at least one hardware processor configured to implement:

a fast Fourier transform device, the fast Fourier transform device comprising a first transform unit and a first data sorting processing unit

the first transform unit performing one of a fast Fourier transform and an inverse fast Fourier transform, generating a plurality of first output data, and outputting the plurality of first output data in a first order, and

the first data sorting processing unit rearranging the plurality of the first output data outputted in the first order, in a second order based on an output order setting;

a complex conjugate generation unit generating second complex data, the second complex data including respective conjugate complex numbers of complex numbers, all of which composing a plurality of frequency-domain first complex data generated by Fourier-transforming a plurality of first input data of inputted time-domain complex numbers by the fast Fourier transform device;

a filter coefficient generation unit generating a first and a second frequency-domain filter coefficients of complex numbers from a first, a second, and a third input filter coefficients of inputted complex numbers;

a first filter unit performing a filtering process on the first complex data with the first frequency-domain filter coefficient and outputting third complex data;

a second filter unit performing a filtering process on the second complex data with the second frequency-domain filter coefficient and outputting fourth complex data; and

a complex conjugate synthesis unit generating fifth complex data by synthesizing the third complex signal and the fourth complex signal.

2. The digital filter device according to claim 1 ,

wherein the first transform unit includes a butterfly computation processing unit performing a butterfly computation process and outputting the plurality of the first output data in the first order, and

the first data sorting unit rearranges in the second order the plurality of the first data after the butterfly computation process.

3. The digital filter device according to claim 1 ,

wherein the first data sorting processing unit includes

a first storage unit storing the plurality of the first output data, and

a read address generation unit generating a read address to read the plurality of the first output data from the first storage unit based on the output order setting,

and stores the plurality of the first output data in the first order and reads the plurality of the first output data in the second order.

4. The digital filter device according to claim 1 ,

wherein the first data sorting processing unit outputs X(k) and X(N−k) at a time lag within one cycle at most for any k, X(k) representing the plurality of the first output data, k representing an integer satisfying 0≦k≦N−1, and N representing the number of points satisfying N>0 for one of a fast Fourier transform and an inverse fast Fourier transform.

5. The digital filter device according to claim 1 , wherein the at least one hardware processor is further configured to implement:

a second data sorting processing unit rearranging a plurality of second input data inputted in a third order, in a fourth order based on an input order setting; and

a second transform unit performing one of a fast Fourier transform and an inverse fast Fourier transform on the plurality of the second input data rearranged in the fourth order,

wherein the second data sorting processing means unit rearranges the fifth complex data inputted in the third order, in the fourth order based on the input order setting,

and the second transform means unit performs an inverse Fourier transform on the fifth complex data rearranged in the fourth order and converts the fifth complex data into time-domain signals.

6. The digital filter device according to claim 2 ,

wherein the first data sorting processing unit includes

a first storage unit storing the plurality of the first output data, and

a read address generation unit generating a read address to read the plurality of the first output data from the first storage unit based on the output order setting,

and stores the plurality of the first output data in the first order and reads the plurality of the first output data in the second order.

7. The digital filter device according to claim 2 ,

wherein the first data sorting processing unit outputs X(k) and X(N−k) at a time lag within one cycle at most for any k, X(k) representing the plurality of the first output data, k representing an integer satisfying 0≦k≦N−1, and N representing the number of points satisfying N>0 for one of a fast Fourier transform and an inverse fast Fourier transform.

8. The digital filter device according to claim 3 ,

wherein the first data sorting processing unit outputs X(k) and X(N−k) at a time lag within one cycle at most for any k, X(k) representing the plurality of the first output data, k representing an integer satisfying 0≦k≦N−1, and N representing the number of points satisfying N>0 for one of a fast Fourier transform and an inverse fast Fourier transform.

9. A digital filter method, comprising:

performing a process for rearranging, based on an output order setting, a plurality of output data generated by one of a fast Fourier transform and an inverse fast Fourier transform;

generating second complex data, the second complex data including respective conjugate complex numbers of complex numbers, all of which composing a plurality of frequency-domain first complex data generated by Fourier-transforming a plurality of first input data of inputted time-domain complex numbers by a fast Fourier transform device;

generating a first and a second frequency-domain filter coefficients of complex numbers from a first, a second, and a third input filter coefficients of inputted complex numbers;

performing a filtering process on the first complex data with the first frequency-domain filter coefficient and outputting third complex data;

performing a filtering process on the second complex data with the second frequency-domain filter coefficient and outputting fourth complex data; and

generating fifth complex data by synthesizing the third complex signal and the fourth complex signal.