低通和高通滤波器在C# [英] lowpass and high pass filter in C#
问题描述
我需要低通和C#编写的高通滤波器。我对这个过滤过程的双阵列。我想,如果我尝试MATLAB巴特沃思和切比雪夫算法转换为C#中,它会更容易。但我无法找到在互联网上butter.m和切比雪夫算法的代码,我不想MATLAB和信号处理工具箱设置成我的电脑。你能提供代码讨好?谢谢..
I need low pass and high pass filter written in c#. I have double arrays for this filter process. I think if I try to convert matlab Butterworth and Chebyshev algorithms to c#, it would be easier. But I couldn't find the code of butter.m and Chebyshev algorithms on the internet and I don't want to set up matlab and signal processing toolbox into my computer. Could you provide that codes please? Thanks..
推荐答案
的 http://www.musicdsp.org/archive.php?classid=3#38
我在执行上面semicode作为过滤器遵循我们的表面肌电分析仪软件,它的伟大工程。
I implemented the filter in semicode above as follows in our sEMG analyzer software and it works great.
public class FilterButterworth
{
/// <summary>
/// rez amount, from sqrt(2) to ~ 0.1
/// </summary>
private readonly float resonance;
private readonly float frequency;
private readonly int sampleRate;
private readonly PassType passType;
private readonly float c, a1, a2, a3, b1, b2;
/// <summary>
/// Array of input values, latest are in front
/// </summary>
private float[] inputHistory = new float[2];
/// <summary>
/// Array of output values, latest are in front
/// </summary>
private float[] outputHistory = new float[3];
public FilterButterworth(float frequency, int sampleRate, PassType passType, float resonance)
{
this.resonance = resonance;
this.frequency = frequency;
this.sampleRate = sampleRate;
this.passType = passType;
switch (passType)
{
case PassType.Lowpass:
c = 1.0f / (float)Math.Tan(Math.PI * frequency / sampleRate);
a1 = 1.0f / (1.0f + resonance * c + c * c);
a2 = 2f * a1;
a3 = a1;
b1 = 2.0f * (1.0f - c * c) * a1;
b2 = (1.0f - resonance * c + c * c) * a1;
break;
case PassType.Highpass:
c = (float)Math.Tan(Math.PI * frequency / sampleRate);
a1 = 1.0f / (1.0f + resonance * c + c * c);
a2 = -2f * a1;
a3 = a1;
b1 = 2.0f * (c * c - 1.0f) * a1;
b2 = (1.0f - resonance * c + c * c) * a1;
break;
}
}
public enum PassType
{
Highpass,
Lowpass,
}
public void Update(float newInput)
{
float newOutput = a1 * newInput + a2 * this.inputHistory[0] + a3 * this.inputHistory[1] - b1 * this.outputHistory[0] - b2 * this.outputHistory[1];
this.inputHistory[1] = this.inputHistory[0];
this.inputHistory[0] = newInput;
this.outputHistory[2] = this.outputHistory[1];
this.outputHistory[1] = this.outputHistory[0];
this.outputHistory[0] = newOutput;
}
public float Value
{
get { return this.outputHistory[0]; }
}
}
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