基于matlab GUI的IIR低通数字滤波器设计(4)

t=0:1/44100:(size(s)-1)/44100; %将所加噪声信号的点数调整到与原始信号相同 Au=0.08; %幅度值

d=Au*cos(2*pi*5000*t); %加余弦信号 频率是5000hz n=d';%将噪声进行转置，以便使噪声与信号的行列相同，进行相加 x=s+n;%原始信号和噪声信号叠加

sound(x);

% --- Executes on button press in pushbutton7.

function pushbutton7_Callback(hObject, eventdata, handles) % hObject handle to pushbutton7 (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) [s,fs]=audioread ('C:\\Users\\昊东\\Desktop\\zhd.wav');%读取语音信号的数据，赋给变量y 信号 频率

t=0:1/44100:(size(s)-1)/44100; %将所加噪声信号的点数调整到与原始信号相同 Au=0.08; %幅度值

d=Au*cos(2*pi*5000*t); %加余弦信号 频率是5000hz n=d';%将噪声进行转置，以便使噪声与信号的行列相同，进行相加 x=s+n;%原始信号和噪声信号叠加

wp=0.08*pi;ws=0.1*pi; %两个频率的信号

Rp=1;Rs=15;Fs=44100;Ts=1/Fs;%阻带衰减和通带衰减，中间是过渡区，采样频率44100

wp1=2/Ts*tan(wp/2);%将数字指标转换成模拟指标 ws1=2/Ts*tan(ws/2);

[N,Wn]=buttord(wp1,ws1,Rp,Rs,'s');%选择滤波器的最小阶数

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[Z,P,K]=buttap(N);%创建butterworth模拟滤波器 [Bap,Aap]=zp2tf(Z,P,K); [b,a]=lp2lp(Bap,Aap,Wn);

[bz,az]=bilinear(b,a,Fs);%用双线性变换法实现模拟滤波器到数字滤波器的转换

[H,W]=freqz(bz,az);%绘制频率响应曲线 y=filter(bz,az,x);%调用上边滤波器函数

sound(y);

% --- Executes on button press in pushbutton8.

function pushbutton8_Callback(hObject, eventdata, handles) % hObject handle to pushbutton8 (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) wp=0.08*pi;ws=0.1*pi; %两个频率的信号

Rp=1;Rs=15;Fs=44100;Ts=1/Fs;%阻带衰减和通带衰减，中间是过渡区，采样频率44100

wp1=2/Ts*tan(wp/2);%将数字指标转换成模拟指标 ws1=2/Ts*tan(ws/2);

[N,Wn]=buttord(wp1,ws1,Rp,Rs,'s');%选择滤波器的最小阶数 [Z,P,K]=buttap(N);%创建butterworth模拟滤波器 [Bap,Aap]=zp2tf(Z,P,K); [b,a]=lp2lp(Bap,Aap,Wn);

[bz,az]=bilinear(b,a,Fs);%用双线性变换法实现模拟滤波器到数字滤波器的转换

[H,W]=freqz(bz,az);%绘制频率响应曲线 plot(handles.axes4,abs(H))

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