private bool DesignBilinear(double fc, double fs, long sampleFreq, AnalogFilterDesign.FilterType filterType)
{
double twoπ = 2.0 * Math.PI;
mIIRBilinear = new BilinearDesign(fc, sampleFreq);
double fc_pw = mIIRBilinear.PrewarpωtoΩ(twoπ * fc) / twoπ;
double fs_pw = mIIRBilinear.PrewarpωtoΩ(twoπ * fs) / twoπ;
mAfd = new AnalogFilterDesign();
mAfd.DesignLowpass(0, CUTOFF_GAIN_DB, StopbandRippleDb(),
fc_pw, fs_pw,
filterType,
ApproximationBase.BetaType.BetaMax);
// 連続時間伝達関数を離散時間伝達関数に変換。
for (int i = 0; i < mAfd.HPfdCount(); ++i)
{
var s = mAfd.HPfdNth(i);
mIIRBilinear.Add(s);
}
mIIRBilinear.Calc();
return(true);
}
public bool Design(double fc, double fs, long samplingFreq, Method method,
AnalogFilterDesign.FilterType filterType = AnalogFilterDesign.FilterType.Cauer)
{
CutoffFreq = fc;
StopbandEdgeFreq = fs;
mMethod = method;
SamplingFrequency = samplingFreq;
switch (method)
{
case Method.Bilinear:
return(DesignBilinear(fc, fs, samplingFreq, filterType));
default:
return(DesignImpulseInvariance(fc, fs, samplingFreq, filterType));
}
}
private bool DesignImpulseInvariance(double fc, double fs, long samplingFreq, AnalogFilterDesign.FilterType filterType)
{
mAfd = new AnalogFilterDesign();
mAfd.DesignLowpass(0, CUTOFF_GAIN_DB, StopbandRippleDb(),
fc,
fs,
filterType,
ApproximationBase.BetaType.BetaMax);
var H_s = new List <FirstOrderComplexRationalPolynomial>();
for (int i = 0; i < mAfd.HPfdCount(); ++i)
{
var p = mAfd.HPfdNth(i);
H_s.Add(p);
}
mIIRiim = new ImpulseInvarianceMethod(H_s, fc * 2.0 * Math.PI, samplingFreq, mMethod == Method.ImpulseInvarianceMinimumPhase);
return(true);
}
private bool GetParametersFromUI()
{
if (!double.TryParse(textBoxG0.Text, out mG0))
{
MessageBox.Show("G0 parse error.");
return(false);
}
if (!double.TryParse(textBoxGc.Text, out mGc) || mG0 <= mGc)
{
MessageBox.Show("Gc parse error. mGc must be smaller than mG0");
return(false);
}
if (!double.TryParse(textBoxGs.Text, out mGs) || mGc <= mGs)
{
MessageBox.Show("Gs parse error. mGs must be smaller than mGc");
return(false);
}
if (!TryParseNumberWithUnit(textBoxFc.Text, out mFc) || mFc <= 0)
{
MessageBox.Show("Fc parse error. Fc must be greater than 0");
return(false);
}
if (!TryParseNumberWithUnit(textBoxFs.Text, out mFs))
{
MessageBox.Show("Fs parse error. Fs must be number.");
return(false);
}
if (mFs <= 0 || mFs <= mFc)
{
MessageBox.Show("Fs parse error. Fs must be greater than Fc and greater than 0");
return(false);
}
mBetaType = ApproximationBase.BetaType.BetaMax;
if (comboBoxOptimization.SelectedItem == comboBoxItemβmin)
{
mBetaType = ButterworthDesign.BetaType.BetaMin;
}
mFilterType = AnalogFilterDesign.FilterType.Butterworth;
if (radioButtonFilterTypeChebyshev.IsChecked == true)
{
mFilterType = AnalogFilterDesign.FilterType.Chebyshev;
}
if (radioButtonFilterTypePascal.IsChecked == true)
{
mFilterType = AnalogFilterDesign.FilterType.Pascal;
}
if (radioButtonFilterTypeInverseChebyshev.IsChecked == true)
{
mFilterType = AnalogFilterDesign.FilterType.InverseChebyshev;
}
if (radioButtonFilterTypeCauer.IsChecked == true)
{
mFilterType = AnalogFilterDesign.FilterType.Cauer;
}
if (!TryParseNumberWithUnit(textBoxSamplingFrequency.Text, out mSamplingFrequency) || mSamplingFrequency <= 0)
{
MessageBox.Show("SamplingFrequency parse error. it must be greater than 0");
return(false);
}
return(true);
}
