数字信号处理课程设计(含完整代码)

课题一数字信号处理系统设计

一、项目要求

用本课程所学的数字信号处理理论知识，设计一个具有信号的采集、处理、传输、显示和存储等功能的系统，内容如下：

１、录制一段语音信号，并对录制的语音信号进行采样（采样频率可取fs=22050Hz）;

２、画出采样后的语音信号的时域波形和频谱图；

３、滤波器的性能指标：

低通滤波器：通带边界频率ｆｐ＝１ｋＨｚ，通带最大衰减Ａｐ＝１ｄB；

阻带边界频率ｆｐ＝１.2ｋＨｚ，阻带最小衰减Ａｐ＝１00ｄB；高通滤波器：通带边界频率ｆｐ＝5ｋＨｚ，通带最大衰减Ａｐ＝１ｄB；

阻带边界频率ｆｐ＝4.8ｋＨｚ，阻带最小衰减Ａｐ＝１00ｄB；带通滤波器：通带上限截止频率fp2=3kHz, 通带下限截止频率fp1=1.2kHz;

阻带上限截止频率fs2=3.2kHz, 通带下限截止频率fp1=1kHz;

通带最大衰减Ap=1dB, 阻带最小衰减As=100dB;

采用双线性变换法设计滤波器，并画出滤波器的频率响应；

４、用自己设计的滤波器对采样的信号进行滤波，画出滤波后信号的时域波形和频谱图，并对滤波前后的信号进行对比，分析信号的变化；

５、回放语音

６、用ＧＵＩ设计一个信号系统的用户界面。

二、实验所要用到的ＭＡＴＬＡＢ函数

１、语音信号的采样与播放

wavread();

[y，fs，bite]=wavread（）；%语音信号的采样

sound（y，fs，bite）；%播放语音

2.滤波器：

IIR：butte（）；%巴特沃思滤波器

cheby1(); %切比雪夫I滤波器

elliptical（）；%椭圆滤波器

3.频率响应：

[h，f]=freqz（b,a,n,fs）

freqz(b,a,n,fs)

5.快速傅里叶变换

fft (x, n)

6.画曲线

plot(x, y)

stem(x, y)

7.在MATLAB中，设计辅助低通原型巴特沃思和切比雪夫滤波器的阶数和截止频率；

1）利用buttord和cheblord确定阶数；

2）[num，den]=butter（N，Wn），[num，den]=cheby1（N，Wn）

3）lp2hp,lp2bp,lp2bs可以完成低通滤波器到高通，带通，带阻的转换

4）使用biliner对模拟滤波器进行双线性变换，求得数字滤波器的传输函数系数

三、数字滤波器（代码）

1.IIR低通滤波器

fp=1000;

ft=5500;

fs=1200;

wp=2*pi*fp/ft;

ws=2*pi*fs/ft;

Fp=2*ft*tan(wp/2);

Fs=2*ft*tan(ws/2);

[n,Omgc]=buttord(Fp,Fs,1,100,'s');

[z,p,k]=buttap(n);

B=k*real(poly(z));

A=real(poly(p));

[b1,a1]=lp2lp(B,A,Omgc);

[ba1,aa1]=bilinear(b1,a1,ft); %模拟转数字[Ha,w]=freqz(ba1,aa1); %求频率相应

plot(w*ft/(2*pi),20*log10(abs(Ha)));

title('IIR 低通滤波器');

xlabel('频率/HZ');

ylabel('幅值');

2.IIR高通滤波器

fp=5000;

ft=25000;%取抽样频率?

fs=4800;

Rp=1;As=100;

wp=2*pi*fp/ft;%通带频率

ws=2*pi*fs/ft;%截止频率

Fp=2*ft*tan(wp/2);

Fs=2*ft*tan(ws/2);

[n,Omgc]=ellipord(Fp,Fs,Rp,As,'s'); %计算阶数n和截止频率[z,p,k]=ellipap(n,Rp,As);

B3=k*real(poly(z));

A3=real(poly(p));

[b3,a3]=lp2hp(B3,A3,Omgc);

[ba3,aa3]=bilinear(b3,a3,ft);

[Ha,w]=freqz(ba3,aa3);

plot(w*ft/(2*pi),20*log10(abs(Ha)));

title('IIR高通滤波器');

xlabel('频率/HZ');

ylabel('幅值');

3.IIR带通滤波器

fp1=1200;fp2=3000;fs1=1000;fs2=3200;ft=10000; As=100;Rp=1;

wp1=2*pi*fp1/ft;

wp2=2*pi*fp2/ft;

ws1=2*pi*fs1/ft;

ws2=2*pi*fs2/ft;

Fp1=2*ft*tan(wp1/2);

Fp2=2*ft*tan(wp2/2);

Fp=[Fp1,Fp2];

Fs1=2*ft*tan(ws1/2);

Fs2=2*ft*tan(ws2/2);

Fs=[Fs1,Fs2];

bw=Fp2-Fp1;w0=sqrt(Fp1*Fp2);%通带宽和中心频率[n,Omgn]=cheb1ord(Fp,Fs,Rp,As,'s');

[z,p,k]=cheb1ap(n,Rp);

B2=k*real(poly(z));

A2=real(poly(p));

[b2,a2]=lp2bp(B2,A2,w0,bw);

[ba2,aa2]=bilinear(b2,a2,ft);

[Ha,w]=freqz(ba2,aa2);

plot(w*ft/(2*pi),20*log10(abs(Ha)));

title('IIR 带通滤波器'); xlabel('频率/HZ'); ylabel('幅值');

四、总代码

function varargout = bzh(varargin)

% BZH M-file for bzh.fig

% BZH, by itself, creates a new BZH or raises the existing

% singleton*.

%

% H = BZH returns the handle to a new BZH or the handle to

% the existing singleton*.

%

% BZH('CALLBACK',hObject,eventData,handles,...) calls the local

% function named CALLBACK in BZH.M with the given input arguments.

%

% BZH('Property','Value',...) creates a new BZH or raises the % existing singleton*. Starting from the left, property value pairs are

% applied to the GUI before ko_OpeningFunction gets called. An % unrecognized property name or invalid value makes property application

% stop. All inputs are passed to bzh_OpeningFcn via varargin. %

% *See GUI Options on GUIDE's Tools menu. Choose "GUI allows

only one

% instance to run (singleton)".

%

% See also: GUIDE, GUIDATA, GUIHANDLES

% Copyright 2002-2003 The MathWorks, Inc.

% Edit the above text to modify the response to help bzh

% Last Modified by GUIDE v2.5 09-Jan-2014 08:54:22

% Begin initialization code - DO NOT EDIT

gui_Singleton = 1;

gui_State = struct('gui_Name', mfilename, ...

'gui_Singleton', gui_Singleton, ...

'gui_OpeningFcn', @bzh_OpeningFcn, ...

'gui_OutputFcn', @bzh_OutputFcn, ...

'gui_LayoutFcn', [] , ...

'gui_Callback', []);

if nargin && ischar(varargin{1})

gui_State.gui_Callback = str2func(varargin{1});

end

if nargout

[varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:}); else

gui_mainfcn(gui_State, varargin{:});

end

% End initialization code - DO NOT EDIT

% --- Executes just before bzh is made visible.

function bzh_OpeningFcn(hObject, eventdata, handles, varargin)

% This function has no output args, see OutputFcn.

% hObject handle to figure

% eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA)

% varargin command line arguments to bzh (see VARARGIN)

% Choose default command line output for bzh

handles.output = hObject;

% Update handles structure

guidata(hObject, handles);

% UIWAIT makes bzh wait for user response (see UIRESUME)

% uiwait(handles.figure1);

% --- Outputs from this function are returned to the command line. function varargout = bzh_OutputFcn(hObject, eventdata, handles) % varargout cell array for returning output args (see VARARGOUT); % hObject handle to figure

% eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA)

% Get default command line output from handles structure

varargout{1} = handles.output;

% --- Executes on button press in tag_start.

function tag_start_Callback(hObject, eventdata, handles)

% hObject handle to tag_start (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) axes(handles.axes1)

cla;

global z0;

global yy;

fs=22050;

nbits=32;

[yy,fs,nbits]=wavread('D:\f.wav'); %语音信号加载

sound(yy,fs); %回放语音

z0=yy;

axes(handles.axes1);

plot(yy);

title('时域采样信号波形');

grid on

n=length(yy); %求出语音信号的长度

Y=fft(yy,n); %傅里叶变换

axes(handles.axes2);

plot(20*log10(abs(Y)));

title('时域采样信号频谱');

guidata(hObject,handles);

grid on

% --- Executes on button press in tag_ditong.

function tag_ditong_Callback(hObject, eventdata, handles)

% hObject handle to tag_ditong (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) axes(handles.axes1)

cla;

global z1;

global yy;

global ba1;

global aa1;

global Fp;

global Fs;

fp=1000;

ft=5500;

fs=1200;

wp=2*pi*fp/ft;

ws=2*pi*fs/ft;

Fp=2*ft*tan(wp/2);

Fs=2*ft*tan(ws/2);

[n,Omgc]=buttord(Fp,Fs,1,100,'s');

[z,p,k]=buttap(n);

B=k*real(poly(z));

A=real(poly(p));

[b1,a1]=lp2lp(B,A,Omgc);

[ba1,aa1]=bilinear(b1,a1,ft); %模拟转数字

z1=filter(ba1,aa1,yy);

[Ha,w]=freqz(ba1,aa1); %求频率相应

plot(w*ft/(2*pi),20*log10(abs(Ha)));

title('IIR 低通滤波器');

xlabel('频率/HZ');

ylabel('幅值');

% --- Executes on button press in tag_gaotong.

function tag_gaotong_Callback(hObject, eventdata, handles)

% hObject handle to tag_gaotong (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) axes(handles.axes2)

cla;

global yy;

global z2;

global B3;

global ba3;

global aa3;

global Fp;

global Fs;

fp=5000;

ft=25000;%取抽样频率?

fs=4800;

Rp=1;As=100;

wp=2*pi*fp/ft;%通带频率

ws=2*pi*fs/ft;%截止频率

Fp=2*ft*tan(wp/2);

Fs=2*ft*tan(ws/2);

[n,Omgc]=ellipord(Fp,Fs,Rp,As,'s'); %计算阶数n和截止频率

[z,p,k]=ellipap(n,Rp,As);

B3=k*real(poly(z));

A3=real(poly(p));

[b3,a3]=lp2hp(B3,A3,Omgc);

[ba3,aa3]=bilinear(b3,a3,ft);

z2=filter(ba3,aa3,yy);

[Ha,w]=freqz(ba3,aa3);

plot(w*ft/(2*pi),20*log10(abs(Ha)));

title('IIR高通滤波器');

xlabel('频率/HZ');

ylabel('幅值');

% --- Executes on button press in tag_daitong.

function tag_daitong_Callback(hObject, eventdata, handles)

% hObject handle to tag_daitong (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) axes(handles.axes3)

cla;

global yy;

global z3;

global B2;

global ba2;

global aa2;

fp1=1200;fp2=3000;fs1=1000;fs2=3200;ft=10000;

As=100;Rp=1;

wp1=2*pi*fp1/ft;

wp2=2*pi*fp2/ft;

ws1=2*pi*fs1/ft;

ws2=2*pi*fs2/ft;

Fp1=2*ft*tan(wp1/2);

Fp2=2*ft*tan(wp2/2);

Fp=[Fp1,Fp2];

Fs1=2*ft*tan(ws1/2);

Fs2=2*ft*tan(ws2/2);

Fs=[Fs1,Fs2];

bw=Fp2-Fp1;w0=sqrt(Fp1*Fp2);%通带宽和中心频率

[n,Omgn]=cheb1ord(Fp,Fs,Rp,As,'s');

[z,p,k]=cheb1ap(n,Rp);

B2=k*real(poly(z));

A2=real(poly(p));

[b2,a2]=lp2bp(B2,A2,w0,bw);

[ba2,aa2]=bilinear(b2,a2,ft);

z3=filter(ba2,aa2,yy);

[Ha,w]=freqz(ba2,aa2);

plot(w*ft/(2*pi),20*log10(abs(Ha)));

title('IIR 带通滤波器');

xlabel('频率/HZ');

ylabel('幅值');

% --- Executes on button press in tag_dibo.

function tag_dibo_Callback(hObject, eventdata, handles)

% hObject handle to tag_dibo (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) axes(handles.axes3)

cla;

global yy;

global z1;

global ba1;

global aa1;

m4=fft(z1);

plot(z1,'y');

title('IIR滤波后的信号波形');

xlabel('时间/t');

ylabel('幅值');

axes(handles.axes4)

cla;

plot(abs(m4),'y');

title('IIR滤波后信号频谱');

xlabel('频率/HZ');

ylabel('幅值');

% --- Executes on button press in tag_gaobo.

function tag_gaobo_Callback(hObject, eventdata, handles)

% hObject handle to tag_gaobo (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) axes(handles.axes3)

cla;

global yy;

global z2;

global B3;

global ba3;

global aa3;

m5=fft(z2);

plot(z2,'y');

title('IIR滤波后的信号波形');

xlabel('时间/t');

ylabel('幅值');

axes(handles.axes4)

cla;

plot(abs(m5),'y');

title('IIR滤波后信号频谱');

xlabel('频率/HZ');

ylabel('幅值');

% --- Executes on button press in tag_daibo.

function tag_daibo_Callback(hObject, eventdata, handles)

% hObject handle to tag_daibo (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) axes(handles.axes3)

cla;

global yy;

global z3;

global B2;

global ba2;

global aa2;

m6=fft(z3);

plot(z3,'y');

title('IIR滤波后的信号波形');

xlabel('时间/t');

ylabel('幅值');

axes(handles.axes4)

cla;

plot(abs(m6),'y');

title('IIR滤波后信号频谱');

xlabel('频率/HZ');

ylabel('幅值');

% --- Executes on selection change in tag_choose.

function tag_choose_Callback(hObject, eventdata, handles)

% hObject handle to tag_choose (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA)

% Hints: contents = get(hObject,'String') returns tag_choose contents as cell array

% contents{get(hObject,'Value')} returns selected item from tag_choose

% --- Executes during object creation, after setting all properties. function tag_choose_CreateFcn(hObject, eventdata, handles)

% hObject handle to tag_choose (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB % handles empty - handles not created until after all CreateFcns called

% Hint: popupmenu controls usually have a white background on Windows. % See ISPC and COMPUTER.

if ispc

set(hObject,'BackgroundColor','white');

else

set(hObject,'BackgroundColor',get(0,'defaultUicontrolBackgroundCo lor'));

end

% --- Executes on button press in tag_return.

function tag_return_Callback(hObject, eventdata, handles)

% hObject handle to tag_return (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) global z0;

global z1;

global z2;

global z3;

global yy;

val=get(handles.tag_choose,'Value');

if(val==1)

[yy,fs,nbits]=wavread('D:\f.wav'); %语音信号加载

sound(yy,fs); %回放语音

end

if(val==2)

sound(z1,22050);

end

if(val==3)

sound(z3,22050);

end

if(val==4)

sound(z2,22050);

end

% --- Executes on mouse press over axes background.

function axes1_ButtonDownFcn(hObject, eventdata, handles)

% hObject handle to axes1 (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA)

% --- If Enable == 'on', executes on mouse press in 5 pixel border. % --- Otherwise, executes on mouse press in 5 pixel border or over tag_start.

function tag_start_ButtonDownFcn(hObject, eventdata, handles)

% hObject handle to tag_start (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA)

采样后信号

滤波器数字波形

IIR低通滤波后波形图

IIR高通滤波后波形图

IIR带通滤波后波形图