低通滤波器软件？

Question

我正在为.net windows表单项目寻找数字低通滤波器代码/库/类,最好用c,c ++或c#编写.我可能需要设置极数,系数,窗口,那种东西.我不能使用任何可用的gpl代码,也不知道还有什么.任何建议赞赏.

Answer 1

这是我为最近的一个项目写的巴特沃斯低通滤波器.

它有一些神奇的数字作为给我的常数.如果你能弄清楚如何使用极点,系数等创建幻数,那么这可能会有所帮助.

using System;
using System.Collections.Generic;
using System.Text;

namespace Filter
{
public class ButterworthLowPassFilter
{

    //filter fc = 2hz, fs = 10hz

    private const int LowPassOrder = 4;

    private double[] inputValueModifier;
    private double[] outputValueModifier;
    private double[] inputValue;
    private double[] outputValue;
    private int valuePosition;

    public ButterworthLowPassFilter()
    {
        inputValueModifier = new double[LowPassOrder];
        inputValueModifier[0] = 0.098531160923927;
        inputValueModifier[1] = 0.295593482771781;
        inputValueModifier[2] = 0.295593482771781;
        inputValueModifier[3] = 0.098531160923927;

        outputValueModifier = new double[LowPassOrder];
        outputValueModifier[0] = 1.0;
        outputValueModifier[1] = -0.577240524806303;
        outputValueModifier[2] = 0.421787048689562;
        outputValueModifier[3] = -0.0562972364918427;
    }

    public double Filter(double inputValue)
    {
        if (this.inputValue == null && this.outputValue == null)
        {
            this.inputValue = new double[LowPassOrder];
            this.outputValue = new double[LowPassOrder];

            valuePosition = -1;

            for (int i=0; i < LowPassOrder; i++)
            {
                this.inputValue[i] = inputValue;
                this.outputValue[i] = inputValue;
            }

            return inputValue;
        }
        else if (this.inputValue != null && this.outputValue != null)
        {
            valuePosition = IncrementLowOrderPosition(valuePosition);

            this.inputValue[valuePosition] = inputValue;
            this.outputValue[valuePosition] = 0;

            int j = valuePosition;

            for (int i = 0; i < LowPassOrder; i++)
            {
                this.outputValue[valuePosition] += inputValueModifier[i] * this.inputValue[j] -
                    outputValueModifier[i] * this.outputValue[j];

                j = DecrementLowOrderPosition(j);
            }

            return this.outputValue[valuePosition];
        }
        else
        {
            throw new Exception("Both inputValue and outputValue should either be null or not null.  This should never be thrown.");
        }
    }

    private int DecrementLowOrderPosition(int j)
    {
        if (--j < 0)
        {
            j += LowPassOrder;
        }
        return j;
    }

    private int IncrementLowOrderPosition(int position)
    {
        return ((position + 1) % LowPassOrder);
    }

}
}

基思