STM32F1 DSP库FFT之后的幅值不对

牧羊人1993 · 发表于 2019-9-28 21:15:44

本帖最后由牧羊人1993 于 2019-9-29 08:45 编辑

我用STM32F1的DSP库进行256点的FFT运算，我尝试了多组不同的数据进行模拟，但是每次计算到的幅值第一个数都特别大，实际频率点的幅值也不对，代码如下，求大神解答一下。。。
#define NPT=256
long lBufOutArray[NPT];/
long lBufInArray[NPT]; //FF
long lBufMagArray[NPT];

int ad_num[NPT]={1720,1700,1650,1580,1520,1450,1440,1520,1640,1720,1700,1650,1580,1520,1450,1440,1520,1640,1720,1700,
1720,1700,1650,1580,1520,1450,1440,1520,1640,1720,1700,1650,1580,1520,1450,1440,1520,1640,1720,1700,
1720,1700,1650,1580,1520,1450,1440,1520,1640,1720,1700,1650,1580,1520,1450,1440,1520,1640,1720,1700,
1720,1700,1650,1580,1520,1450,1440,1520,1640,1720,1700,1650,1580,1520,1450,1440,1520,1640,1720,1700,
1720,1700,1650,1580,1520,1450,1440,1520,1640,1720,1700,1650,1580,1520,1450,1440,1520,1640,1720,1700,
1720,1700,1650,1580,1520,1450,1440,1520,1640,1720,1700,1650,1580,1520,1450,1440,1520,1640,1720,1700,
1720,1700,1650,1580,1520,1450,1440,1520,1640,1720,1700,1650,1580,1520,1450,1440,1520,1640,1720,1700,
1720,1700,1650,1580,1520,1450,1440,1520,1640,1720,1700,1650,1580,1520,1450,1440,1520,1640,1720,1700,
1720,1700,1650,1580,1520,1450,1440,1520,1640,1720,1700,1650,1580,1520,1450,1440,1520,1640,1720,1700,
1720,1700,1650,1580,1520,1450,1440,1520,1640,1720,1700,1650,1580,1520,1450,1440,1520,1640,1720,1700,
1720,1700,1650,1580,1520,1450,1440,1520,1640,1720,1700,1650,1580,1520,1450,1440,1520,1640,1720,1700,
1720,1700,1650,1580,1520,1450,1440,1520,1640,1720,1700,1650,1580,1520,1450,1440,1520,1640,1720,1700,
1720,1700,1650,1580,1520,1450,1440,1520,1640,1720,1700,1650,1580,1520,1450,1440};

void FFT_jisuan(void)
{
InitBufInArray();
cr4_fft_256_stm32(lBufOutArray,lBufInArray,NPT);
GetPowerMag();

}