MATLAB信号的幅度调制和解调.doc

一、任务与题目分析:1.设计任务:在MATLAB的图形窗口中，实现2-3个有限带宽信号的调制与解调。显示各个信号的时域波形及频谱图；通过按钮选择其中的一个信号进行解调并显示解调信号的波形。2.任务分析:设带限信号的频谱为，现将乘以载波信号，即得到已调信号：，如下图。实现信号解调的原理图如下图。若要从多个已调信号中解调出其中的一个信号，只需将已调信号再乘以该已调信号的载波信号，并进行低通率波即可得到原信号。下图是多路频分复用系统的示意图。二、方案设计 信号设计：。，。载波信号频率应远大于。方案一：使用GUI图形届面显示信号的时域及频域波形。低通滤波器：可以使用理想数字低通滤波器。方案二：使用Simulink界面实现信号的处理，使用示波器观测信号的时域波形；使用频谱仪显示信号的频谱图。模拟低通滤波器：可选用巴特沃斯低通滤波器。综合两种方案的特点,最终选择方案一.三、算法设计1. GUI界面设计2.GUI程序设计信号时域波形与频谱显示控制程序部分:% - Executes on button press in pushbutton1.function pushbutton1_Callback(hObject, eventdata, handles)% hObject handle to pushbutton1 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA) st1=str2double(get(handles.edit3,string);st2=str2double(get(handles.edit2,string);t = eval(get(handles.edit4,String); m1=get(handles.radiobutton1,value);m2=get(handles.radiobutton2,value);m3=get(handles.radiobutton3,value);persistent cif isempty(c) c=0endc=c+1;if(m1=1) if(st2=(5*st1) errordlg(输入数值违规，输入w0值应大于5倍的信号频率 ，请重新输入！) elsef=sin(st1.*t)+sin(3*st1.*t)/3; g=cos(st2.*t); w1=st1 w2=3*st1 h=fft(f) Fp=abs(h); Xp=angle(h) if(mod(c,2)=0) % Create frequency plotaxes(handles.shiyu)plot(t,f,r);set(handles.shiyu,XMinorTick,on)grid on; % Create pinyu plotaxes(handles.pinyu)plot(t,Fp,b);set(handles.pinyu,XMinorTick,on)xlabel(幅频特性)grid on str=sprintf(f1=sin(%d*t)+sin(%d*t)/%d,w1,w2,w2);set(handles.text9,string,str); str=sprintf(g=cos(%d*t),st2);set(handles.text6,string,str);endif(mod(c,2)=0) axes(handles.pinyu)plot(t,Xp,b);set(handles.pinyu,XMinorTick,on)xlabel(相频特性)grid on axes(handles.shiyu)plot(t,f,r);set(handles.shiyu,XMinorTick,on)grid on; str=sprintf(f1=sin(%d*t)+sin(%d*t)/%d,w1,w2,w2);set(handles.text9,string,str); str=sprintf(g=cos(%d*t),st2);set(handles.text6,string,str); endendend if(m2=1) if(st2=(5*st1) errordlg(输入数值违规，输入w0值应大于5倍的信号频率 ，请重新输入！) else f=sin(st1.*t)+sin(3*st1.*t)/3+cos(2*st1.*t)/2; g=cos(st2.*t); w1=st1 w2=3*st1 w3=2*st1 h=fft(f) Fp=abs(h); Xp=angle(h) if(mod(c,2)=0) % Create frequency plotaxes(handles.shiyu)plot(t,f,r);set(handles.shiyu,XMinorTick,on)grid on; % Create pinyu plotaxes(handles.pinyu)plot(t,Fp,b);set(handles.pinyu,XMinorTick,on)xlabel(幅频特性)grid on str=sprintf(f2=sin(%d*t)+sin(%d*t)/%d+cos(%d*t)/%d,w1,w2,w2,w3,w3);set(handles.text9,string,str); str=sprintf(g=cos(%d*t),st2);set(handles.text6,string,str);endif(mod(c,2)=0) axes(handles.pinyu)plot(t,Xp,b);set(handles.pinyu,XMinorTick,on)xlabel(相频特性)grid on axes(handles.shiyu)plot(t,f,r);set(handles.shiyu,XMinorTick,on)grid on; str=sprintf(f2=sin(%d*t)+sin(%d*t)/%d+cos(%d*t)/%d,w1,w2,w2,w3,w3);set(handles.text9,string,str); str=sprintf(g=cos(%d*t),st2);set(handles.text6,string,str); endendend if(m3=1) if(st2=(5*st1) errordlg(输入数值违规，输入w0值应大于5倍的信号频率 ，请重新输入！) else f=sin(st1.*t)+cos(3*st1.*t)/3; g=cos(st2.*t); w1=st1 w2=3*st1 h=fft(f) Fp=abs(h); Xp=angle(h) if(mod(c,2)=0) % Create frequency plotaxes(handles.shiyu)plot(t,f,r);set(handles.shiyu,XMinorTick,on)grid on; % Create pinyu plotaxes(handles.pinyu)plot(t,Fp,b);set(handles.pinyu,XMinorTick,on)xlabel(幅频特性)grid on str=sprintf(f3=sin(%d*t)+cos(%d*t)/%d,w1,w2,w2);set(handles.text9,string,str); str=sprintf(g=cos(%d*t),st2);set(handles.text6,string,str);endif(mod(c,2)=0) axes(handles.pinyu)plot(t,Xp,b);set(handles.pinyu,XMinorTick,on)xlabel(相频特性)grid on axes(handles.shiyu)plot(t,f,r);set(handles.shiyu,XMinorTick,on)grid on; str=sprintf(f3=sin(%d*t)+cos(%d*t)/%d,w1,w2,w2);set(handles.text9,string,str); str=sprintf(g=cos(%d*t),st2);set(handles.text6,string,str); endendend 信号调制波形显示程序:% - Executes on button press in pushbutton2.function pushbutton2_Callback(hObject, eventdata, handles)% hObject handle to pushbutton2 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)st1=str2double(get(handles.edit3,string);st2=str2double(get(handles.edit2,string)t = eval(get(handles.edit4,String); m1=get(handles.radiobutton1,value);m2=get(handles.radiobutton2,value);m3=get(handles.radiobutton3,value);if(m1=1) if(st2=(5*st1) errordlg(输入数值违规，输入w0值应大于5倍的信号频率 ，请重新输入！) else f=sin(st1.*t)+sin(3*st1.*t)/3; g=cos(st2.*t); ft=f.*g w1=st1 w2=3*st1 axes(handles.tiaozhi)plot(t,ft,r);set(handles.tiaozhi,XMinorTick,on)xlabel(调制波形)grid on axes(handles.shiyu)plot(t,f,b);set(handles.shiyu,XMinorTick,on)grid on; str=sprintf(f1=sin(%d*t)+sin(%d*t)/%d,w1,w2,w2);set(handles.text9,string,str); str=sprintf(g=cos(%d*t),st2);set(handles.text6,string,str); endend if(m2=1) if(st2=(5*st1) errordlg(输入数值违规，输入w0值应大于5倍的信号频率 ，请重新输入！) else f=sin(st1.*t)+sin(3*st1.*t)/3+cos(2*st1.*t)/2; g=cos(st2.*t); ft=f.*g w1=st1 w2=3*st1 axes(handles.tiaozhi)plot(t,ft,r);set(handles.tiaozhi,XMinorTick,on)xlabel(调制波形)grid on axes(handles.shiyu)plot(t,f,b);set(handles.shiyu,XMinorTick,on)grid on; str=sprintf(f2=sin(%d*t)+sin(%d*t)/%d+cos(%d*t)/%d,w1,w2,w2,w3,w3);set(handles.text9,string,str); str=sprintf(g=cos(%d*t),st2);set(handles.text6,string,str); endend if(m3=1) if(st2=(5*st1) errordlg(输入数值违规，输入w0值应大于5倍的信号频率 ，请重新输入！) else f=sin(st1.*t)+cos(3*st1.*t)/3; g=cos(st2.*t); ft=f.*g w1=st1 w2=3*st1 axes(handles.tiaozhi)plot(t,ft,r);set(handles.tiaozhi,XMinorTick,on)xlabel(调制波形)grid on axes(handles.shiyu)plot(t,f,b);set(handles.shiyu,XMinorTick,on)grid on; str=sprintf(f3=sin(%d*t)+cos(%d*t)/%d,w1,w2,w2);set(handles.text9,string,str); str=sprintf(g=cos(%d*t),st2);set(handles.text6,string,str); endend 解调信号波形显示程序: % - Executes on button press in pushbutton6.function pushbutton6_Callback(hObject, eventdata, handles)% hObject handle to pushbutton6 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA) st1=str2double(get(handles.edit3,string);st2=str2double(get(handles.edit2,string)t = eval(get(handles.edit4,String); m1=get(handles.radiobutton1,value);m2=get(handles.radiobutton2,value);m3=get(handles.radiobutton3,value);if(m1=1) if(st2=(5*st1) errordlg(输入数值违规，输入w0值应大于5倍的信号频率 ，请重新输入！) else f=sin(st1.*t)+sin(3*st1.*t)/3; g=cos(st2.*t); ft=f.*g.*g w1=st1 w2=3*st1 axes(handles.jietiao)plot(t,ft,r);set(handles.jietiao,XMinorTick,on)xlabel(解调波形)grid on axes(handles.shiyu)plot(t,f,b);set(handles.shiyu,XMinorTick,on)grid on; str=sprintf(f1=sin(%d*t)+sin(%d*t)/%d,w1,w2,w2);set(handles.text9,string,str); str=sprintf(g=cos(%d*t),st2);set(handles.text6,string,str); endend if(m2=1) if(st2=(5*st1) errordlg(输入数值违规，输入w0值应大于5倍的信号频率 ，请重新输入！) else f=sin(st1.*t)+sin(3*st1.*t)/3+cos(2*st1.*t)/2; g=cos(st2.*t); ft=f.*g.*g w1=st1 w2=3*st1 axes(handles.jietiao)plot(t,ft,r);set(handles.jietiao,XMinorTick,on)xlabel(解调波形)grid on axes(handles.shiyu)plot(t,f,b);set(handles.shiyu,XMinorTick,on)grid on; str=sprintf(f2=sin(%d*t)+sin(%d*t)/%d+cos(%d*t)/%d,w1,w2,w2,w3,w3);set(handles.text9,string,str); str=sprintf(g=cos(%d*t),st2);set(handles.text6,string,str); endend if(m3=1) if(st2=(5*st1) errordlg(输入数值违规，输入w0值应大于5倍的信号频率 ，请重新输入！) else f=sin(st1.*t)+cos(3*st1.*t)/3; g=cos(st2.*t); ft=f.*g.*g w1=st1 w2=3*st1 axes(handles.jietiao)plot(t,ft,r);set(handles.jietiao,XMinorTick,on)xlabel(解调波形)grid on axes(handles.shiyu)plot(t,f,b)set(handles.shiyu,XMinorTick,on)grid on; str=sprintf(f3=sin(%d*t)+cos(%d*t)/%d,w1,w2,w2);set(handles.text9,string,str); str=sprintf(g=cos(%d*t),st2);set(handles.text6,string,str); endend四、MATLAB实现1. 载波信号:g=cos(w0*t); 选取信号1: f1=sin(w1*t)+sin(3*w1*t)/t; 设定载波频率w0=6;信号频率w1=1;时间向量t:0:0.01:2*pi; 执行情况一: 幅频特性执行情况二:相频特性2. 载波信号:g=cos(w0*t); 选取信号2: f2=sin(w1*t)+sin(3*w1*t)/t+cos(2*w1*t); 设定载波频率w0=6;信号频率w1=1;时间向量t:0:0.01:2*pi;执行情况一:幅频特性执行情况二:(相频特性)五、结果分析 （1）原始信号以及频谱的分析：由于原始信号是正信号，所以经傅里叶变换后经设计得出图形。故正确得出了原始信号的频谱 （2）对于已调信号则是由原信号与载波信号相乘的结果。由于正弦函数幅度均匀，故与载波相乘后，幅度分