Realizing method and device of fast Fourier transform applied in communication field
Realizing method and device of fast Fourier transform applied in communication field
 CN 101,551,790 B
 Filed: 04/03/2008
 Issued: 11/05/2014
 Est. Priority Date: 04/03/2008
 Status: Active Grant
First Claim
1. be applied to a fast fourier transform implementation method for the communications field, for the data that receive are carried out, after overflow control, carry out Fourier transform, it is characterized in that, comprising:
 Power detector is according to the exponent number of the data that receive, predetermined interval is divided into a plurality of subranges, obtain the shift value of each data in the data that receive, and therefrom obtain the shift value of absolute value maximum, wherein, described shift value represents that the residing subrange of described data is with respect to the position relationship in the appointment subrange in described a plurality of subranges, wherein, described predetermined interval is divided into being treated to of described a plurality of subranges;
utilize following formula according to the exponent number of the described data that receive, to determine the size in each subrange;
[1/2 ^{n1}, 1/2 ^{n}), wherein, n=0,1,2 ..., m, and m is the exponent number of the described data that receive;
The first power governor utilizes the described shift value of absolute value maximum to modify respectively to described each data, the new data of acquisition after corresponding to described each data modification, wherein, utilize being treated to that the described shift value of absolute value maximum modifies respectively to described each data;
if the described shift value of absolute value maximum is positive number, described each data are multiplied by respectively 2 SHIFT power, wherein, SHIFT is shift value;
If the described shift value of absolute value maximum is negative, described each data are respectively divided by 2 SHIFT power, wherein, and the shift value that SHIFT is described each data;
Fourier transform module is carried out fast fourier transform to described new data.
Chinese PRB Reexamination
Abstract
The invention provides a realizing method of fast Fourier transform, which is used for controlling the overflow of received data and then carrying out the Fourier transform. The realizing method of the fast Fourier transform comprises the following steps: dividing a predetermined area into a plurality of subareas according to the exponent number of received data; obtaining a shifting value of each datum of the received data and also obtaining a shifting value with a maximal absolute value from the obtained shifting values; utilizing the shifting value with the maximal absolute value to respectively modify each datum and obtaining new modified data corresponding to each datum; and carrying out the fast Fourier transform for the new data, wherein the shifting values express the position relation of the subarea where the data locating relative to a pointed subarea of the subareas. Besides, the invention also provides a realizing device of the fast Fourier transform. The invention can ensure the calculation precision under the precondition of overflow control and can also reduce the utilization of circuit resources, lower the circuit cost and enhance the qualification rate of circuits.
8 Claims

1. be applied to a fast fourier transform implementation method for the communications field, for the data that receive are carried out, after overflow control, carry out Fourier transform, it is characterized in that, comprising:

Power detector is according to the exponent number of the data that receive, predetermined interval is divided into a plurality of subranges, obtain the shift value of each data in the data that receive, and therefrom obtain the shift value of absolute value maximum, wherein, described shift value represents that the residing subrange of described data is with respect to the position relationship in the appointment subrange in described a plurality of subranges, wherein, described predetermined interval is divided into being treated to of described a plurality of subranges;
utilize following formula according to the exponent number of the described data that receive, to determine the size in each subrange;
[1/2 ^{n1}, 1/2 ^{n}), wherein, n=0,1,2 ..., m, and m is the exponent number of the described data that receive;
The first power governor utilizes the described shift value of absolute value maximum to modify respectively to described each data, the new data of acquisition after corresponding to described each data modification, wherein, utilize being treated to that the described shift value of absolute value maximum modifies respectively to described each data;
if the described shift value of absolute value maximum is positive number, described each data are multiplied by respectively 2 SHIFT power, wherein, SHIFT is shift value;
If the described shift value of absolute value maximum is negative, described each data are respectively divided by 2 SHIFT power, wherein, and the shift value that SHIFT is described each data;Fourier transform module is carried out fast fourier transform to described new data.


2. method according to claim 1, is characterized in that, described predetermined interval is set to [0,1].

3. method according to claim 1, is characterized in that, determines that the processing of the shift value of described each data is specially:

Described a plurality of subranges are numbered since 1 with interval order from big to small, and using maximum subrange as described appointment subrange; By following formula, determine respectively the shift value of described each data;
SHIFT=4Tk, wherein, SHIFT is shift value, and Tk is the numbering in the residing subrange of data.


4. method according to claim 2, is characterized in that, determines that the processing of the shift value of described each data is specially:

Described a plurality of subranges are numbered since 1 with interval order from big to small, and using maximum subrange as described appointment subrange; By following formula, determine respectively the shift value of described each data;
SHIFT=4Tk, wherein, SHIFT is shift value, and Tk is the numbering in the residing subrange of data.


5. method according to claim 1, it is characterized in that, in the situation that described a plurality of data are nonreal number, for described each data, determine its real part and the imaginary part numbering in residing subrange respectively, and according to following formula, determine the shift value of described each data:
 SHIFT=3min (nxk, nyk), wherein, the shift value that SHIFT is data, nxk is that to subtract 1, nyk be that the subrange number at the imaginary part place of described data subtracts 1 in the subrange number at the real part place of described data.

6. method according to claim 2, it is characterized in that, in the situation that described a plurality of data are nonreal number, for described each data, determine its real part and the imaginary part numbering in residing subrange respectively, and according to following formula, determine the shift value of described each data:
 SHIFT=3min (nxk, nyk), wherein, the shift value that SHIFT is data, nxk is that to subtract 1, nyk be that the subrange number at the imaginary part place of described data subtracts 1 in the subrange number at the real part place of described data.

7. according to the method described in any one in claim 1 to 6, it is characterized in that, in the situation that there are the not data in described subrange, the exponent number of the described data that the shift value of these data is set to receive adds 1.

8. be applied to a fast fourier transform implement device for the communications field, for the data that receive are carried out, after overflow control, carry out Fourier transform, it is characterized in that, comprising:

Power detector, the exponent number of the data that receive for basis, predetermined interval is divided into a plurality of subranges, and the shift value that obtains each data in the data that receive, and therefrom obtain the shift value of absolute value maximum, wherein, described shift value represents that the residing subrange of described data is with respect to the position relationship in the appointment subrange in described a plurality of subranges, wherein, the following formula of described power detector utilization is determined the size in each subrange according to the exponent number of the described data that receive;
[1/2 ^{n1}, 1/2 ^{n}), wherein, n=0,1,2 ..., m, and m is the exponent number of the described data that receive;
The first power governor, for utilizing the described shift value of absolute value maximum to modify respectively to described each data, the new data of acquisition after corresponding to described each data modification, wherein, described the first power governor utilizes being treated to that the described shift value of absolute value maximum modifies respectively to described each data;
if the described shift value of absolute value maximum is positive number, described each data are multiplied by respectively 2 SHIFT power, and wherein, SHIFT is shift value;
If the described shift value of absolute value maximum is negative, described each data are respectively divided by 2 SHIFT power, wherein, and the shift value that SHIFT is described each data;Fourier transform module, for carrying out fast fourier transform to described new data.

Specification(s)