数字信号仿真实验——实验四有限冲激响应数字滤波器的设计

た入场券 2023-10-05 13:42 48阅读 0赞

## 1.实验目的 ##

![在这里插入图片描述][20201115170636161.bmp_pic_center]

## 2.实验原理 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyMDc4OTM0_size_16_color_FFFFFF_t_70_pic_center]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyMDc4OTM0_size_16_color_FFFFFF_t_70_pic_center 1]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyMDc4OTM0_size_16_color_FFFFFF_t_70_pic_center 2]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyMDc4OTM0_size_16_color_FFFFFF_t_70_pic_center 3]  
![在这里插入图片描述][20201115170855293.bmp_pic_center]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyMDc4OTM0_size_16_color_FFFFFF_t_70_pic_center 4]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyMDc4OTM0_size_16_color_FFFFFF_t_70_pic_center 5]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyMDc4OTM0_size_16_color_FFFFFF_t_70_pic_center 6]

## 3.实验内容 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyMDc4OTM0_size_16_color_FFFFFF_t_70_pic_center 7]  
![在这里插入图片描述][20201115171105421.bmp_pic_center]  
![在这里插入图片描述][20201115171124900.bmp_pic_center]

## 4.实验报告要求 ##

![在这里插入图片描述][2020111517115012.bmp_pic_center]

## Matlab程序1： ##

Problem1
    N=15
    wn=[0.3 0.5];
    n=input('Type in the length n=');
    win=hanning(n+1);%hanning窗函数
    b1=fir1(n,wn,'bandpass',win)%带通
    freqz(b1,1);
    title('Made by LEI')
    
    
    
    N=45
    wn=[0.3 0.5];
    n=input('Type in the length n=');
    win=hanning(n+1);%hanning窗函数
    b1=fir1(n,wn,'bandpass',win)%带通
    freqz(b1,1);
    title('Made by LEI')

## 运行结果1： ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyMDc4OTM0_size_16_color_FFFFFF_t_70_pic_center 8]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyMDc4OTM0_size_16_color_FFFFFF_t_70_pic_center 9]

## 实验分析1： ##

实验分析：随着N值的增大，主瓣变窄，旁瓣数量增加，波纹减小。

## Matlab程序2\_1： ##

Problem2_1
    N=15
    wn=[0.3 0.5];
    n=input('Type in the length n=');
    win=boxcar(n+1);%矩形窗
    b1=fir1(n,wn,'bandpass',win)%带通
    freqz(b1,1);
    title('Made by LEI')
    
    
    N=45
    
    wn=[0.3 0.5];
    n=input('Type in the length n=');
    win=boxcar(n+1);%矩形窗
    b1=fir1(n,wn,'bandpass',win)%带通
    freqz(b1,1);
    title('Made by LEI')

运行结果2\_1：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyMDc4OTM0_size_16_color_FFFFFF_t_70_pic_center 10]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyMDc4OTM0_size_16_color_FFFFFF_t_70_pic_center 11]

## Matlab程序2\_2： ##

Problem2_2
    
    N=15
    wn=[0.3 0.5];
    n=input('Type in the length n=');
    win=blackman(n+1);%blackman窗
    b1=fir1(n,wn,'bandpass',win)%带通
    freqz(b1,1);
    title('Made by LEI')
    
    
    
    N=45
    wn=[0.3 0.5];
    n=input('Type in the length n=');
    win=blackman(n+1);%blackman窗
    b1=fir1(n,wn,'bandpass',win)%带通
    freqz(b1,1);
    title('Made by LEI')

## 运行结果2\_2： ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyMDc4OTM0_size_16_color_FFFFFF_t_70_pic_center 12]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyMDc4OTM0_size_16_color_FFFFFF_t_70_pic_center 13]

## 实验分析2： ##

实验分析：矩形窗的旁瓣比hanning窗的旁瓣水平降低，Blackman窗旁瓣水平最低。

## Matlab程序3： ##

Problem3
    
    
    wn=[0.2 0.4 0.6 0.8];
    n=40;
    beta=input('beta=');
    win=kaiser(n+1,beta);%kaiser窗
    b1=fir1(n,wn,win)
    freqz(b1,1);
    title('Made by LEI')
    
    
    
    
    
    
    
    
    
    
    wn=[0.2 0.4 0.6 0.8];
    n=40;
    beta=input('beta=');
    win=kaiser(n+1,beta);%kaiser窗
    b1=fir1(n,wn,win)
    freqz(b1,1);
    title('Made by LEI')
    
    
    
    
    wn=[0.2 0.4 0.6 0.8];
    n=40;
    beta=input('beta=');
    win=kaiser(n+1,beta);%kaiser窗
    b1=fir1(n,wn,win)
    freqz(b1,1);
    title('Made by LEI')

## 运行结果3： ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyMDc4OTM0_size_16_color_FFFFFF_t_70_pic_center 14]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyMDc4OTM0_size_16_color_FFFFFF_t_70_pic_center 15]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyMDc4OTM0_size_16_color_FFFFFF_t_70_pic_center 16]

## 实验分析3： ##

实验分析：Kaiser窗的频带内能量主要集中在主瓣中，它有最好的旁瓣抑制性能。随着B值的增大，对旁瓣的一直性能越好。

## Matlab程序4： ##

Problem4
    
    clear
    wn=0.3;
    n=input('Type in the length n=');
    win=hanning(n+1);
    b1=fir1(n,wn,'low',win)
    figure(1)
    freqz(b1,1);
    title('Made by LEI')
    x=[-4 -2 0 -4 -6 -4 -2 -6 -6 -4 -4 -6 -6 -2 6 12 8 0 -16 -38 -60 -84 -90 -66 -32 -4 -2 -4 8 12 12 10 6 6 6 4 0 0 0 0 0 -2 -4 0 0 0 -2 -2 0 0 -2 -2 -2 -2 0];
    figure(2)
    subplot(211)
    plot(x)
    title('Made by LEI')
    y=filter(b1,1,x);
    subplot(212)
    plot(y)
     
    figure(3)
    subplot(211)
    N=100
    n=0:N-1;
    mf=fft(x,N);
    stem(n,abs(mf));
    title('Made by LEI')
    y=filter(b1,1,x);
    mfa=fft(y,N);
    subplot(212)
    stem(n,abs(mfa));

## 运行结果4： ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyMDc4OTM0_size_16_color_FFFFFF_t_70_pic_center 17]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyMDc4OTM0_size_16_color_FFFFFF_t_70_pic_center 18]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyMDc4OTM0_size_16_color_FFFFFF_t_70_pic_center 19]  
**本人能力有限，解释尚不清楚明了，如遇任何问题，大家可留言或私信。后续将程序文件打包上传，供大家学习使用。**

**本文希望对大家有帮助，当然上文若有不妥之处，欢迎指正。**

**分享决定高度，学习拉开差距**

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