public static float[,] GetDiscreteSpectre(float[,] data)
{
int w = data.GetLength(0);
int h = data.GetLength(1);
int lenX = (int)Math.Pow(2, Math.Ceiling(Math.Log(w, 2)));
int lenY = (int)Math.Pow(2, Math.Ceiling(Math.Log(h, 2)));
var compData = new Exocortex.DSP.Complex[lenX * lenY];
for (int i = 0; i < w; i++)
{
for (int j = 0; j < h; j++)
{
compData[i * h + j].Re = data[i, j];
}
}
Exocortex.DSP.Fourier.FFT2(compData, lenX, lenY, Exocortex.DSP.FourierDirection.Forward);
var res = new float[w, h];
for (int i = 0; i < w; i++)
{
for (int j = 0; j < h; j++)
{
res[i, j] = (float)Math.Sqrt(Math.Pow(compData[i * h + j].Re, 2) + Math.Pow(compData[i * h + j].Im, 2));
}
}
return(res);
}
/// <summary>
/// находим приблизительную частоту пульса
/// (как основную частоту периодического сигнала ФПГ)
/// </summary>
/// <param name="data"></param>
/// <returns></returns>
public double find_main_frequency(double[] data)
{
{
int N;
for (N = 2; N * 2 < data.Length && N *2 <= 4096; N *= 2)
{
;
}
Exocortex.DSP.Complex[] fdata = new Exocortex.DSP.Complex[N];
for (int ii = 0; ii < N; ++ii)
{
fdata[ii] = new Exocortex.DSP.Complex(data[ii], 0);
}
Exocortex.DSP.Fourier.FFT(fdata, N, Exocortex.DSP.FourierDirection.Forward);
double max = System.Double.MinValue;
int i_max = -1;
double modulus;
for (int i = 0; i < N; i += 2)
{
modulus = fdata[i].GetModulusSquared();
if (modulus > max)
{
i_max = i;
max = modulus;
}
}
return(((double)fdata.Length) / ((double)i_max));
}
}
public static float[] GetDiscreteSpectre(float[] data)
{
var compData = new Exocortex.DSP.Complex[4096];
for (int i = 0; i < Math.Min(data.Length, compData.Length); i++)
{
compData[i].Re = data[i];
}
Exocortex.DSP.Fourier.FFT(compData, compData.Length, Exocortex.DSP.FourierDirection.Forward);
return(GetDiscrete(compData));
}
/// <summary>
/// return a in complex power b
/// </summary>
/// <param name="b"></param>
/// <returns></returns>
static Exocortex.DSP.Complex pow(Exocortex.DSP.Complex a, Exocortex.DSP.Complex b)
{
double r = a.GetModulus();
double teta = a.GetArgument();
double c = b.Re;
double d = b.Im;
Exocortex.DSP.Complex r1 = new Exocortex.DSP.Complex(Math.Pow(r, c) * Math.Exp(-d * teta), 0);
Exocortex.DSP.Complex r2 = new Exocortex.DSP.Complex(Math.Cos(d * Math.Log(r) + c * teta), Math.Sin(d * Math.Log(r) + c * teta));
return(r1 * r2);
}
/// <summary>
/// вычисляет спектр сигнала
/// </summary>
/// <param name="spectrum"></param>
/// <returns></returns>
public static Spectrum CalculateSpectrum(int[] signal, double SamplingRate)
{
if (signal.Length < 1)
{
throw new ArgumentException();
}
//signal = DownsampleSignal(signal);
//signal = ResampleSignalToPowerOf2(signal, ref SamplingRate);
//signal = GenerateSinus(signal, SamplingRate);
//signal = GenerateMeander(signal, SamplingRate);
int length = 1;
while (((length * 2) < signal.Length) && ((2 * length) < (512 * 1024)))
{
length *= 2;
}
// remove constant
signal = CenterSignal(signal, length);
Exocortex.DSP.Complex[] complex_data = new Exocortex.DSP.Complex[length];
for (int i = 0; i < length; ++i)
{
complex_data[i].Re = signal[i];
complex_data[i].Im = 0;
}
Exocortex.DSP.Fourier.FFT(complex_data, length, Exocortex.DSP.FourierDirection.Forward);
// calculate power
Spectrum result = new Spectrum();
result.FreqResolution = SamplingRate / 2 / (((double)length) / 2);
result.SpectrumLow = 0;
result.SpectrumHigh = SamplingRate / 2;
for (int k = 0; k < (length / 2); ++k)
{
result.SpectrumBins.Add(
System.Math.Sqrt(
complex_data[k].Re * complex_data[k].Re +
complex_data[k].Im * complex_data[k].Im
)
);
}
return(result);
}
static public EDSPComplex[] AM2EDSP(AMComplex[,] Source)
{
int Height = Source.GetLength(0), Width = Source.GetLength(1);
EDSPComplex[] Result = new EDSPComplex[Width * Height];
int Y, X, T = 0;
for (Y = 0; Y < Height; ++Y)
{
for (X = 0; X < Width; ++X)
{
Result[T] = new EDSPComplex(Source[Y, X].Re, Source[Y, X].Im);
++T;
}
}
return(Result);
}
