FFT算法查表法.docx

FFT算法查表法.docx

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FFT算法查表法

ARM或单片机用的FFT算法,用于信号处理。

经过愚昧的本人优化,提高了计算效率

（在aduc7026@41MHzFFT256点环境下运算时间为0.06s左右）

PS:

以下有两部分（fft.h和fft.c）

【复制以下内容改名为fft.h】

#ifndef__FFT_H__

#define__FFT_H__

#include

#ifdefFFT_GLOBALS

#defineFFT_EXT

#else

#defineFFT_EXTextern

#endif

#definePI3.1415926

#defineFFT_POINT8//设置点数（此值变,下面的也要变）（0~11）

#defineSAMPLE_NUM256//可设256或512两种数

//count[n]

//count[]={1,2,4,8,16,32,64,128,256,512,1024,2048}

FFT_EXTfloatdataR[SAMPLE_NUM];

FFT_EXTfloatdataI[SAMPLE_NUM];

FFT_EXTvoidSetData（floatdata,unsignedinti）;//采集数据到第i个点（0~SAMPLE_NUM）

FFT_EXTvoidFFT（void）;//采样来的数据放在dataR[]数组中

//***************FFT结果数值处理*******************************************************

//计算和返回峰（模）值,k表示第几个值（0~SAMPLE_NUM-1）,type为0返回峰值,1返回模值,2返回有效值

FFT_EXTfloatGetPeak（unsignedintk,unsignedinttype）;

//FFT_EXTfloatGetPhase（unsignedintk,unsignedinttype）;//计算和返回相位,k同上

//type为0返回角度,1返回弧度

//speed为采样速率,返回第k（0~SAMPLE_NUM）个点代表的频率

FFT_EXTfloatGetStepF（floatspeed,unsignedintk）;

FFT_EXTfloatGetPower1（unsignedintk）;//返回功率谱的第k点

FFT_EXTfloatGetPower2（unsignedintk,floattotal）;//返回k点所占的功率百分比（单位是%）total为总功率

FFT_EXTfloatGetTotalPower（void）;//计算功率谱总和

FFT_EXTfloatGetTHD（void）;//计算失真度

#endif

///////////////////////////////////////////////////////////////////////////////

【复制以下内容改名为fft.c】

//查表式FFT算法

#defineFFT_GLOBALS

#include"fft.h"

#ifSAMPLE_NUM==256

constfloatsin_tab[256]={0.000000,0.024541,0.049068,0.073565,0.098017,0.122411,0.146730,0.170962,0.195090,0.219101,0.242980,0.266713,0.290285,0.313682,0.336890,0.359895,0.382683,

0.405241,0.427555,0.449611,0.471397,0.492898,0.514103,0.534998,0.555570,0.575808,0.595699,0.615232,0.634393,0.653173,0.671559,0.689541,0.707107,

0.724247,0.740951,0.757209,0.773010,0.788346,0.803208,0.817585,0.831470,0.844854,0.857729,0.870087,0.881921,0.893224,0.903989,0.914210,0.923880,

0.932993,0.941544,0.949528,0.956940,0.963776,0.970031,0.975702,0.980785,0.985278,0.989177,0.992480,0.995185,0.997290,0.998795,0.999699,1.000000,

0.999699,0.998795,0.997290,0.995185,0.992480,0.989177,0.985278,0.980785,0.975702,0.970031,0.963776,0.956940,0.949528,0.941544,0.932993,0.923880,

0.914210,0.903989,0.893224,0.881921,0.870087,0.857729,0.844854,0.831470,0.817585,0.803208,0.788346,0.773010,0.757209,0.740951,0.724247,0.707107,

0.689541,0.671559,0.653173,0.634393,0.615232,0.595699,0.575808,0.555570,0.534998,0.514103,0.492898,0.471397,0.449611,0.427555,0.405241,0.382683,

0.359895,0.336890,0.313682,0.290285,0.266713,0.242980,0.219101,0.195090,0.170962,0.146730,0.122411,0.098017,0.073565,0.049068,0.024541,0.000000,

-0.024541,-0.049068,-0.073565,-0.098017,-0.122411,-0.146730,-0.170962,-0.195090,-0.219101,-0.242980,-0.266713,-0.290285,-0.313682,-0.336890,-0.359895,-0.382683,

-0.405241,-0.427555,-0.449611,-0.471397,-0.492898,-0.514103,-0.534998,-0.555570,-0.575808,-0.595699,-0.615232,-0.634393,-0.653173,-0.671559,-0.689541,-0.707107,

-0.724247,-0.740951,-0.757209,-0.773010,-0.788346,-0.803208,-0.817585,-0.831470,-0.844854,-0.857729,-0.870087,-0.881921,-0.893224,-0.903989,-0.914210,-0.923880,

-0.932993,-0.941544,-0.949528,-0.956940,-0.963776,-0.970031,-0.975702,-0.980785,-0.985278,-0.989177,-0.992480,-0.995185,-0.997290,-0.998795,-0.999699,-1.000000,

-0.999699,-0.998795,-0.997290,-0.995185,-0.992480,-0.989177,-0.985278,-0.980785,-0.975702,-0.970031,-0.963776,-0.956940,-0.949528,-0.941544,-0.932993,-0.923880,

-0.914210,-0.903989,-0.893224,-0.881921,-0.870087,-0.857729,-0.844854,-0.831470,-0.817585,-0.803208,-0.788346,-0.773010,-0.757209,-0.740951,-0.724247,-0.707107,

-0.689541,-0.671559,-0.653173,-0.634393,-0.615232,-0.595699,-0.575808,-0.555570,-0.534998,-0.514103,-0.492898,-0.471397,-0.449611,-0.427555,-0.405241,-0.382683,

-0.359895,-0.336890,-0.313682,-0.290285,-0.266713,-0.242980,-0.219101,-0.195090,-0.170962,-0.146730,-0.122411,-0.098017,-0.073565,-0.049068,-0.024541};

#endif

#ifSAMPLE_NUM==512

constfloatsin_tab[512]={0.000000,0.012272,0.024541,0.036807,0.049068,0.061321,0.073565,0.085797,0.098017,0.110222,0.122411,0.134581,0.146730,0.158858,0.170962,0.183040,0.195090,0.207111,0.219101,0.231058,0.242980,0.254866,0.266713,0.278520,0.290285,0.302006,0.313682,0.325310,0.336890,0.348419,0.359895,0.371317,0.382683,

0.393992,0.405241,0.416430,0.427555,0.438616,0.449611,0.460539,0.471397,0.482184,0.492898,0.503538,0.514103,0.524590,0.534998,0.545325,0.555570,0.565732,0.575808,0.585798,0.595699,0.605511,0.615232,0.624859,0.634393,0.643832,0.653173,0.662416,0.671559,0.680601,0.689541,0.698376,0.707107,

0.715731,0.724247,0.732654,0.740951,0.749136,0.757209,0.765167,0.773010,0.780737,0.788346,0.795837,0.803208,0.810457,0.817585,0.824589,0.831470,0.838225,0.844854,0.851355,0.857729,0.863973,0.870087,0.876070,0.881921,0.887640,0.893224,0.898674,0.903989,0.909168,0.914210,0.919114,0.923880,

0.928506,0.932993,0.937339,0.941544,0.945607,0.949528,0.953306,0.9569