public LowFirFilterProcess()
{
var lowCoefficient = FirCoefficients.LowPass(HeartContext.F, 37, 40);
LowFirFilter = new OnlineFirFilter(lowCoefficient);
}
public double[] Derivative(double[] filteredSignal)
{
Delay += 2;
IList<double> hd_coef = new List<double>();
double[] hd_array = { -1, -2, 0, 2, 1 };
foreach (double num in hd_array)
{
hd_coef.Add(num);
}
OnlineFirFilter diffFilter = new OnlineFirFilter(hd_coef);
double[] derivativeSignal = diffFilter.ProcessSamples(filteredSignal);
return derivativeSignal;
}
public BandStopFirFilterProcess()
{
var bandCoefficient = FirCoefficients.BandStop(HeartContext.F, 45, 50, 40);
BandFirFilter = new OnlineFirFilter(bandCoefficient);
}
public Vector<double> TransformImf(Vector<double>[] imfs, uint fs)
{
//result Vector
Vector<double> imfSum = Vector<double>.Build.Dense(imfs[0].Count - 2);
//integrating window
double window = Math.Round(0.1 * fs);
Delay += Convert.ToUInt32(window / 2);
foreach (Vector<double> imf in imfs)
{
//nonlinear transform
Vector<double> imfTransformed = Vector<double>.Build.Dense(imf.Count);
for (int i = 2; i < imfs[0].Count; i++)
{
if ((imf[i] * imf[i - 1] > 0) && (imf[i - 2] * imf[i] > 0))
{
imfTransformed[i] = Math.Abs(imf[i] * imf[i - 1] * imf[i - 2]);
}
else
{
imfTransformed[i] = 0;
}
}
imfTransformed = imfTransformed.SubVector(2, imf.Count - 2);
//integrating
IList<double> hi_coeff = new List<double>();
for (int i = 0; i < window; i++)
{
hi_coeff.Add(1 / window);
}
OnlineFirFilter integrationFilter = new OnlineFirFilter(hi_coeff);
double[] imfIntegrated = integrationFilter.ProcessSamples(imfTransformed.ToArray());
//sum
imfSum = imfSum.Add(Vector<double>.Build.DenseOfArray(imfIntegrated));
}
return imfSum;
}
public double[] Integration(double[] htSignal, uint fs)
{
double[] int1Signal = new double[htSignal.Length];
double window = Math.Round(0.37 * fs);
Delay += Convert.ToUInt32(Math.Round(window / 2));
IList<double> hi_coeff = new List<double>();
for (int i = 0; i < window; i++)
{
hi_coeff.Add((1 / window) + 1);
}
OnlineFirFilter integrationFilter = new OnlineFirFilter(hi_coeff);
int1Signal = integrationFilter.ProcessSamples(htSignal);
Vector<double> tempSignal = Vector<double>.Build.DenseOfArray(int1Signal);
// correcting signal length
Vector<double> int2Signal = CutSignal(tempSignal, Convert.ToInt16(Math.Round(window / 2)), htSignal.Length - 1);
int sigLength = htSignal.Length - Convert.ToInt16(Math.Round(window / 2));
// normalization
double tempMax = int2Signal.Maximum();
double tempMin = int2Signal.Minimum();
double normCoeff = (Math.Abs(tempMin) > tempMax) ? Math.Abs(tempMin) : tempMax;
double[] integratedSignal = new double[sigLength];
for (int i = 0; i < sigLength; i++)
{
integratedSignal[i] = int2Signal[i] / normCoeff;
}
return integratedSignal;
}
public double[] Integrating(double[] squaredSignal, uint fs)
{
double[] integratedSignal = new double[squaredSignal.Length];
double window = Math.Round(0.15 * fs);
Delay += Convert.ToUInt32(Math.Round(window / 2));
IList<double> hi_coeff = new List<double>();
for (int i = 0; i < window; i++)
{
hi_coeff.Add(1 / window);
}
OnlineFirFilter integrationFilter = new OnlineFirFilter(hi_coeff);
integratedSignal = integrationFilter.ProcessSamples(squaredSignal);
//enhancing by put zero below threshold (0.002)
for (int i = 0; i < integratedSignal.Length; i++)
{
if (integratedSignal[i] < 0.002)
integratedSignal[i] = 0;
}
return integratedSignal;
}
public double[] HilbertTransform(double[] filteredSignal)
{
double pi = Math.PI;
IList<double> d = new List<double>();
d.Add(1 / (pi * filteredSignal.Length));
OnlineFirFilter transformFilter = new OnlineFirFilter(d);
double[] hSignal = transformFilter.ProcessSamples(filteredSignal);
double[] htSignal = new double[hSignal.Length];
for (int i = 0; i < htSignal.Length; i++)
{
htSignal[i] = Math.Abs(filteredSignal[i]) + Math.Abs(hSignal[i]);
}
return htSignal;
}
public double[] Filtering(double samplingFreq, double lowCutOff, double highCutOff, double[] rawSignal)
{
//TO DO: add cutoffs as constants not param?
Delay += 10;
IList<double> coef = new List<double>();
double[] hf = FirCoefficients.BandPass(samplingFreq, lowCutOff, highCutOff, 10);
foreach (double number in hf)
{
coef.Add(number);
}
OnlineFirFilter filter = new OnlineFirFilter(coef);
double[] vector_f = filter.ProcessSamples(rawSignal);
return vector_f;
}
public BandPassFirFilterProcess()
{
var bandCoefficient = FirCoefficients.BandPass(HeartContext.F, 1, 37, 50);
BandFirFilter = new OnlineFirFilter(bandCoefficient);
}