private void FourierSpectrumAnalysis(object o)
{
try
{
double[][] data = FourierWindows.Calculate(FourierWindows.SplitData(this.Channel, 2048), this.SelectedWindowType, float.Parse(this.Sigma));
int[] freq = new int[data.Length];
for (int i = 0; i < freq.Length; i++)
{
double[] data2 = new double[data[i].Length];
for (int j = 0; j < data[i].Length; j++)
{
if (j != 0)
{
data2[j] = data[i][j] - 0.94 * data[i][j - 1];
}
else
{
data2[j] = data[i][j];
}
}
List <Complex> signal = new List <Complex>();
for (int j = 0; j < data2.Length; j++)
{
signal.Add(new Complex(data2[j], 0));
}
List <Complex> dft = AMath.CalculateFastTransform(signal, AMath.CalculateWCoefficients(data2.Length, false), 0);
dft.RemoveRange(dft.Count / 2, dft.Count / 2);
double[] spectrum = new double[dft.Count];
for (int j = 0; j < spectrum.Length; j++)
{
spectrum[j] = Math.Sqrt((dft[j].Re * dft[j].Re) + (dft[j].Im * dft[j].Im));
}
List <int> max = new List <int>();
for (int j = 1; j < spectrum.Length - 1; j++)
{
if (spectrum[j - 1] < spectrum[j] && spectrum[j + 1] < spectrum[j])
{
max.Add(j);
}
}
int globalMax = 0;
double globalMaxVal = 0;
for (int j = 0; j < max.Count; j++)
{
int index = max[j];
double value = spectrum[index];
if (value > globalMaxVal)
{
globalMax = index;
globalMaxVal = value;
}
}
double border = 0.2 * globalMaxVal;
List <int> bordered = new List <int>();
for (int j = 0; j < max.Count; j++)
{
if (spectrum[max[j]] >= border)
{
bordered.Add(max[j]);
}
}
double median;
if (bordered.Count > 1)
{
List <double> differences = new List <double>();
for (int j = 0; j < max.Count - 1; j++)
{
for (int k = j + 1; k < max.Count; k++)
{
differences.Add(Math.Abs(max[j] - max[k]));
}
}
differences.Sort();
if (differences.Count != 1)
{
if (differences.Count % 2 == 0)
{
median = differences[differences.Count / 2];
}
else
{
int half = (differences.Count - 1) / 2;
median = (differences[half] + differences[half + 1]) / 2;
}
}
else
{
median = differences[0];
}
}
else
{
median = bordered[0];
}
freq[i] = Convert.ToInt32((this.SampleRate / data[i].Length) * median);
}
this.FourierFreq = freq;
}
catch (Exception e)
{
Notify.Error(e.Message);
}
}
