/// <summary>
/// 对于时域a[]转换为频率Y(f),参数b为0
/// </summary>
/// <param name="a"></param>
/// <param name="b"></param>
/// <returns></returns>
public static int FFTData0(double[] a, double[] b, double Fs, out double[] Y, out double[] f)
{
try
{
int L = a.Length;//采样个数
if (b == null)
{
b = new double[L];
}
int NFFT = TWFFT.funTwo(L);//最靠近大于2的幂数NFFT，有点问题
Y = new double[NFFT / 2 + 1];
f = new double[NFFT / 2 + 1];
TWFFT.FFT(a, b);
#if DEBUG
FileUtils.StorageDatum(string.Format(@"FFTResult{0}.txt", DateTime.Now.ToString("HHmmss")), a, b);
#endif
for (int i = 0; i < NFFT / 2 + 1; i++)
{
double j = (double)i / (NFFT / 2);
f[i] = Fs / 2 * j;
}
for (int i = 0; i < NFFT / 2 + 1; i++)
{
Y[i] = 2 * (double)Math.Sqrt(Math.Pow(a[i], 2) + Math.Pow(b[i], 2)) / L;
}
return(NFFT / 2 + 1);
}
catch (Exception ee)
{
throw ee;
}
}
/// <summary>
/// 对于时域a[]转换为频率Y(f),参数b为0
/// </summary>
/// <param name="a"></param>
/// <param name="b"></param>
/// <returns></returns>
public static int FFTData1(double[] a, double[] b, double Fs, out double[] Y, out double[] f)
{
try
{
int L = a.Length; //采样个数
int NFFT = TWFFT.funTwo(L); //最靠近大于2的幂数NFFT，有点问题
Y = new double[NFFT / 2 + 1];
f = new double[NFFT / 2 + 1];
double[] ax = new double[NFFT];
double[] bx = new double[NFFT];
Array.Copy(a, 0, ax, 0, L);
if (b != null)
{
Array.Copy(b, 0, bx, 0, L);
}
TWFFT.FFT(ax, bx);
for (int i = 0; i < NFFT / 2 + 1; i++)
{
double j = (double)i / (NFFT / 2);
f[i] = Fs / 2 * j;
}
for (int i = 0; i < NFFT / 2 + 1; i++)
{
Y[i] = 2 * (double)Math.Sqrt(Math.Pow(ax[i], 2) + Math.Pow(bx[i], 2)) / L;
}
return(NFFT / 2 + 1);
}
catch (Exception ee)
{
throw ee;
}
}
/// <summary>
/// 对于时域a[]转换为频率Y(f),参数b为0
/// 数据总量可大于每次FFT计算的nCount，多次FFT计算求平均
/// </summary>
/// <param name="a"></param>
/// <param name="b"></param>
/// <returns></returns>
public static bool FFTData(double[] a, double fs, int nCount, out double[] Y, out double[] f)
{
try
{
int len = a.Length;
int TotalCnt = 0;
int index = 0;
double[] tmp = new double[nCount];
Y = new double[nCount / 2 + 1];
while (index < len)
{
int n = 0;
for (int i = index; i < index + nCount; i++)
{
if (i < len)
{
tmp[n] = a[i];
}
else
{
tmp[n] = 0f;
}
n++;
}
var b = new double[nCount];
TWFFT.FFT(tmp, b);
//直流分量
Y[0] += (double)Math.Sqrt(Math.Pow(tmp[0], 2) + Math.Pow(b[0], 2)) / nCount;
for (int i = 1; i < nCount / 2 + 1; i++)
{
Y[i] += 2 * (double)Math.Sqrt(Math.Pow(tmp[i], 2) + Math.Pow(b[i], 2)) / nCount;
}
index += nCount;
TotalCnt++;
}
for (int i = 0; i < nCount / 2 + 1; i++)
{
Y[i] = Y[i] / TotalCnt;
}
f = new double[nCount / 2 + 1];
for (int i = 0; i < nCount / 2 + 1; i++)
{
double j = (double)i / (nCount / 2);
f[i] = fs / 2 * j;
}
return(true);
}
catch (Exception ee)
{
throw ee;
}
}