public static List <Complex[]> Direct(double[] wavein, DSP.Window.Type wnd = DSP.Window.Type.Hann, UInt32 wlength = 1024, UInt32 fftPad = 0)
{
var wlength2 = wlength / 2;
double numWindow = (wavein.Length / (wlength / 2)) - 1;
List <Complex[]> result = new List <Complex[]>();
// ciclo su array di campioni lunghi wlength e sovrapposti al 50% tra loro
for (uint i = 0; i < numWindow; i++)
{
result.Add(wavein.Slice(i * wlength2, wlength).Window(Window.Type.Hann).FFT(fftPad));
}
return(result);
}
private void SpectrumPrepare(int chanel, Chart PlotChart)
{
uint N = Convert.ToUInt32(saveDataTable.Rows.Count);
double[] orignalData = new double[N];
double samplingRateHz = 1000;
string windowFFT = "Hamming";
DSP.Window.Type windowToApply = (DSP.Window.Type)Enum.Parse(typeof(DSP.Window.Type), windowFFT);
double[] wc = DSP.Window.Coefficients(windowToApply, N);
double windowScaleFactor = DSP.Window.ScaleFactor.Signal(wc);
// the sum of N and zeros must be power of 2.
int pow2 = 1;
while (N > Math.Pow(2, pow2))
{
pow2++;
}
uint zeros = Convert.ToUInt32(Math.Pow(2, pow2)) - N;
// Instantiate & Initialize the FFT class
FFT fft = new FFT();
fft.Initialize(N, zeros);
foreach (DataRow dr in saveDataTable.Rows)
{
// copy saveDataTable to array "orignailData"
orignalData[saveDataTable.Rows.IndexOf(dr)] = Convert.ToDouble(dr[chanel]);
}
// remove the mean
orignalData = DSP.Math.RemoveMean(orignalData);
// Calculate the frequency span
double[] fSpan = fft.FrequencySpan(samplingRateHz);
// Convert and Plot Log Magnitude
Complex[] cpxResult = fft.Execute(orignalData);
double[] magResult = DSP.ConvertComplex.ToMagnitude(cpxResult);
magResult = DSP.Math.Multiply(magResult, windowScaleFactor);
double[] magLog = DSP.ConvertMagnitude.ToMagnitudeDBV(magResult);
PlotChart.Series["Series1"].Points.Clear();
PlotChart.Series["Series1"].Points.DataBindXY(fSpan, magResult);
}
public override float[] doFFT(float[] samples, WINDOW_TYPE window)
{
double[] dSamples = new double[samples.Length];
for (int i = 0; i < samples.Length; i++)
{
dSamples[i] = (double)samples[i];
}
//Code from DSPLib documentation
DSP.Window.Type dspWindow = getWindowType(window);
double[] windowCoefs = DSP.Window.Coefficients(dspWindow, (UInt32)this.binSize);
double[] windowInputData = DSP.Math.Multiply(dSamples, windowCoefs);
double windowScaleFactor = DSP.Window.ScaleFactor.Signal(windowCoefs);
System.Numerics.Complex[] complexSpectrum = fft.Execute(windowInputData);
//Convert to magnitude and multiply by the window scale factor to get our binned array
double[] fftSpectrum = DSP.Math.Multiply(DSPLib.DSP.ConvertComplex.ToMagnitude(complexSpectrum), windowScaleFactor);
float[] fFFTSpectrum = new float[fftSpectrum.Length];
for (int i = 0; i < fFFTSpectrum.Length; i++)
{
fFFTSpectrum[i] = (float)fftSpectrum[i];
}
return(fFFTSpectrum);
}
public static List <Complex[]> STFT(this double[] wavein, DSP.Window.Type wnd = DSP.Window.Type.Hann, UInt32 wlength = 1024, UInt32 fftpad = 0)
{
return(mdsplib.FT.STFT.Direct(wavein, wnd, wlength, fftpad));
}
