private FilterInfo CreateFilter(int lowFrequency, int highFrequency, int filterOrder)
{
double[] coefficients = FirCoefficients.BandPass(SamplingRate, lowFrequency, highFrequency, filterOrder);
OnlineFirFilter filter = new OnlineFirFilter(coefficients);
return(new FilterInfo(filter, lowFrequency, highFrequency));
}
/// <summary>
/// Create a filter to remove middle (all but low and high) frequencies in online processing scenarios.
/// </summary>
public static OnlineFilter CreateBandstop(ImpulseResponse mode, double sampleRate, double cutoffLowRate, double cutoffHighRate, int order)
{
if (mode == ImpulseResponse.Finite)
{
double[] c = FirCoefficients.BandStop(sampleRate, cutoffLowRate, cutoffHighRate, order >> 1);
return(new OnlineFirFilter(c));
}
if (mode == ImpulseResponse.Infinite)
{
double[] c = IirCoefficients.BandStop(sampleRate, cutoffLowRate, cutoffHighRate);
return(new OnlineIirFilter(c));
}
throw new ArgumentException("mode");
}
/// <summary>
/// Create a filter to remove low frequencies in online processing scenarios.
/// </summary>
public static OnlineFilter CreateHighpass(ImpulseResponse mode, double sampleRate, double cutoffRate, int order)
{
if (mode == ImpulseResponse.Finite)
{
double[] c = FirCoefficients.HighPass(sampleRate, cutoffRate, order >> 1);
return(new OnlineFirFilter(c));
}
if (mode == ImpulseResponse.Infinite)
{
// TODO: investigate (bandwidth)
double[] c = IirCoefficients.HighPass(sampleRate, cutoffRate, cutoffRate);
return(new OnlineIirFilter(c));
}
throw new ArgumentException("mode");
}
/**
* 零相位延迟FIR滤波
* @param:
* dataSerial 输入波形
* samplingFreq 采样率 Hz
* lowCutOff 低截至频率 Hz
* highCutOff 高截至频率 Hz
*
* @return FIRResult 滤波后数据
*/
public double[] ZeroPhaseFIR(double[] dataSerial, double samplingFreq, double lowCutOff, double highCutOff)
{
IList <double> coef = new List <double>();
double[] hf = FirCoefficients.BandPass(samplingFreq, lowCutOff, highCutOff, 64); //获得滤波系数
foreach (double number in hf)
{
coef.Add(number);
}
OnlineFirFilter filter = new OnlineFirFilter(coef);
double[] FIRResult = filter.ProcessSamples(dataSerial); //正向滤波
FIRResult = filter.ProcessSamples(FIRResult.Reverse().ToArray()); //反向滤波
FIRResult = FIRResult.Reverse().ToArray(); //反转
return(FIRResult);
}
public OnlineFirFilter SetFilter(CtkPassFilterStruct pfarg)
{
var flag = this.filter != null;
flag &= this.FilterArgs.Mode == pfarg.Mode;
flag &= this.FilterArgs.SampleRate == pfarg.SampleRate;
flag &= this.FilterArgs.CutoffLow == pfarg.CutoffLow;
flag &= this.FilterArgs.CutoffHigh == pfarg.CutoffHigh;
if (flag)
{
return(filter);
}
this.FilterArgs = pfarg;
var coff = new double[0];
switch (this.FilterArgs.Mode)
{
case CtkEnumPassFilterMode.BandPass:
coff = FirCoefficients.BandPass(this.FilterArgs.SampleRate, this.FilterArgs.CutoffLow, this.FilterArgs.CutoffHigh);
break;
case CtkEnumPassFilterMode.LowPass:
coff = FirCoefficients.LowPass(this.FilterArgs.SampleRate, this.FilterArgs.CutoffLow);
break;
case CtkEnumPassFilterMode.HighPass:
coff = FirCoefficients.HighPass(this.FilterArgs.SampleRate, this.FilterArgs.CutoffHigh);
break;
default:
throw new NotImplementedException();
}
filter = new OnlineFirFilter(coff);
return(filter);
}
private void RefreshCoefficient()
{
double[] coefficient = null;
SoftPanelGlobalInfo globalInfo = SoftPanelGlobalInfo.GetInstance();
FilterType type = (FilterType)Enum.Parse(typeof(FilterType), metroComboBox_type.Text);
double lowCutoff = double.Parse(textBox_lowerCutoff.Text);
double highCutoff = double.Parse(textBox_highCutoff.Text);
switch (type)
{
case FilterType.LowPass:
coefficient = FirCoefficients.LowPass(globalInfo.SampleRate, lowCutoff);
break;
case FilterType.HighPass:
coefficient = FirCoefficients.HighPass(globalInfo.SampleRate, highCutoff);
break;
case FilterType.BandPass:
if (lowCutoff > highCutoff)
{
double tmp = lowCutoff;
lowCutoff = highCutoff;
highCutoff = tmp;
}
coefficient = FirCoefficients.BandPass(globalInfo.SampleRate, lowCutoff, highCutoff);
break;
case FilterType.BandStop:
if (lowCutoff > highCutoff)
{
double tmp = lowCutoff;
lowCutoff = highCutoff;
highCutoff = tmp;
}
coefficient = FirCoefficients.BandStop(globalInfo.SampleRate, lowCutoff, highCutoff);
break;
}
_filter = new OnlineFirFilter(coefficient);
}
