CMSIS-DSP库做FFT,如何求相位？

只看该作者 · 2019-6-27 15:03

代码在官方的例子里稍做修改而来,频率计算准确.相位不对.

#include "arm_math.h"
#include "arm_const_structs.h"
#define TEST_LENGTH_SAMPLES 256
#if TEST_LENGTH_SAMPLES==2048
#define ARM_CFFT_SR_F32_LEN arm_cfft_sR_f32_len1024
#elif TEST_LENGTH_SAMPLES==1024
#define ARM_CFFT_SR_F32_LEN arm_cfft_sR_f32_len512
#elif TEST_LENGTH_SAMPLES==512
#define ARM_CFFT_SR_F32_LEN arm_cfft_sR_f32_len256
#elif TEST_LENGTH_SAMPLES==256
#define ARM_CFFT_SR_F32_LEN arm_cfft_sR_f32_len128
#endif
//#define TEST_F 2300
uint16_t  TEST_F =  5000;
/* -------------------------------------------------------------------
* External Input and Output buffer Declarations for FFT Bin Example
* ------------------------------------------------------------------- */
float32_t testInput_f32_10khz[TEST_LENGTH_SAMPLES*2];
static float32_t testOutput[TEST_LENGTH_SAMPLES/2];
/* ------------------------------------------------------------------
* Global variables for FFT Bin Example
* ------------------------------------------------------------------- */
uint32_t fftSize = TEST_LENGTH_SAMPLES/2;
uint32_t ifftFlag = 0;
uint32_t doBitReverse = 1;
/* Reference index at which max energy of bin ocuurs */
uint32_t refIndex = 213, testIndex = 0;
volatile float32_t ph;
/* ----------------------------------------------------------------------
* Max magnitude FFT Bin test
* ------------------------------------------------------------------- */
float32_t fre1;
float32_t n;
int32_t main(void)
{
  uint16_t i,j=0;
  arm_status status;
  float32_t maxValue;

  status = ARM_MATH_SUCCESS;
      while(1)
      {
            //for(i=0; i<fftSize; i++)TEST_LENGTH_SAMPLES
            n++;
            for(i=0; i<TEST_LENGTH_SAMPLES; i++)
            {
                     testInput_f32_10khz[i*2+1] = 0;
                     testInput_f32_10khz[i*2] = arm_sin_f32(2*3.1415926f*TEST_F/10000*i+PI/180*n);//模拟一路5K正弦信号，10K采样
            }
      for(i=1;i<TEST_LENGTH_SAMPLES;i++)//
            {
                     //testInput_f32_10khz[i*2]=testInput_f32_10khz[i*2]*conv[i-1];
            }
            for(i=0;i<TEST_LENGTH_SAMPLES/2;i++)//
            {
                     //testInput_f32_10khz[i*2]+=testInput_f32_10khz[(i+TEST_LENGTH_SAMPLES/2)*2];
            }
      /* Process the data through the CFFT/CIFFT module */
      arm_cfft_f32(&ARM_CFFT_SR_F32_LEN, testInput_f32_10khz, ifftFlag, doBitReverse);
      /* Process the data through the Complex Magnitude Module for
      calculating the magnitude at each bin */
      arm_cmplx_mag_f32(testInput_f32_10khz, testOutput, fftSize);
      /* Calculates maxValue and returns corresponding BIN value */
      arm_max_f32(testOutput, fftSize, &maxValue, &testIndex);
      fre1=((float)(testIndex)/fftSize)*10000;                //计算频率
      maxValue=atan2(testInput_f32_10khz[testIndex+1],testInput_f32_10khz[testIndex]);
            ph=maxValue;
            ph*=180;
            ph/=PI;                   //角度
      if(testIndex !=  refIndex)
      {
            status = ARM_MATH_TEST_FAILURE;
      }
      }                         /* main function does not return */
}