用于数字通信系统的仿真 MATLAB

function HUWei(p,noisesigma) k=p; %输入的键盘编号（16个键） show=0; %控制是否显示输出波形（调试用） freqmap=[697 697 697 697 770 770 770 770 852 852 852 852 941 941 941 941; 1209 1336 1477 1633 1209 1336 1477 1633 1209 1336 1477 1633 1209 1336 1477 1633];%16个键的对应频率 string=sym('[1,2,3,A,4,5,6,B,7,8,9,C,*,0,#,D]'); %16个键对应的数字或符号 freq1=freqmap(1,k); %低频部分 freq2=freqmap(2,k); %高频部分 fs=8*10^3; %采样频率 sigtime=45; %DTMF持续时间 wholetime=100; %静音加DTMF的持续时间 %y1=[]; %分配空间 [y1,number]=DTMFproduce(freq1,fs,sigtime,wholetime); %调用函数 [y2,number]=DTMFproduce(freq2,fs,sigtime,wholetime); %调用函数 %======================================================================= if show==1 figure plot(y1+y2); %双音信号显示 title('DTMF信号'); end %============================高斯白噪声生成=============== %加入高斯白噪声 m=0; %噪声均值 sigma=noisesigma; %噪声方差 noise=gngauss(m,sigma,number); %高斯白噪声生成 %============================高斯白噪声============================ if show==1 figure plot(noise); title('高斯白噪声'); end %========================DTMF信号与噪声叠加结果==================== %信道信号 signal=y1+y2+noise; if show==1 figure plot(signal); title('DTMF信号与噪声叠加结果'); end %====================接收端DTMF判决程序与数据采样=============== %也可以将接收信号反转，代表随机延迟 delay=round(50*rand+1)+350; %随机延迟 receive(1,1:delay)=signal(1,800-delay+1:800); receive(1,delay+1:800)=signal(1,1:800-delay); %receive=zeros(1,800); %反转 %receive=signal(end:-1:1); % %对于800个点 %接收信号区开始判决 %thresh=2*sigma; %平均能量门限 thresh=2.5; Length=300; %采样数据长度（太短不行） a=zeros(1,20); sample=zeros(1,Length); finished=0; for i=1:1:800-5 if(finished==0) a(1,1:5)=receive(1,i:i+4); if(sum(a)>thresh&&i<(800-Length)) sample(1,1:Length)=receive(1,i:i+Length-1); finished=1; %得到采样数据 end if i>=(800-Length-10) waitfor(errorDlg('信号到达检测出现错误！'));return; end; end end %===========================接收端采样结果显示======================== if show==1 figure plot(sample); title('接收端采样结果显示'); end %===========================采样数据频谱显示=========================== Topmax=(freqmap*Length/8000); %所有双音频信号频率对应点 Y=abs(fft(sample)); %求幅度谱 if show==1 figure plot(Y); title('采样数据频谱显示'); end %=========================极值点判断============================ DATA=zeros(1,2); %频谱极值点保存数据 YY=Y(1,1:Length/2); %取一半的频谱 MAX=max(YY); %频谱幅值最大值 m=0; for i=3:1:(Length/2-1) if(YY(1,i)>=YY(1,i+1))&&(YY(1,i)>=YY(1,i-1))&&(YY(1,i)>(MAX/3)) %极值位置点判断 %注意：上面的方法又不太完善的地方，可以进一步改进的 m=m+1; DATA(1,m)=i; end end %将极值点位置与16个已知频点位置进行比较，最近点对应相应键的数字或符号 BB(1,:)=DATA(1,1)*ones(1,16); BB(2,:)=DATA(1,2)*ones(1,16); Adjust=Topmax-BB; PAN=Adjust.*Adjust; Hu=sum(PAN,1); %距离（均方） Data=find(Hu==min(min(Hu))); %找到极值点的位置 string(1,Data) %显示相应的按键符号 %===================================================================== figure(2) subplot(311) plot(y1+y2); title('DTMF信号'); subplot(312) plot(noise); title('高斯白噪声'); subplot(313) plot(signal); title('DTMF信号与噪声叠加结果'); figure(3); subplot(211);plot(receive);title('随机延迟的DTMF接收信号'); figure(4) subplot(211) plot(sample); title('接收端采样结果显示'); subplot(212) plot(Y); title('采样数据频谱显示'); figure(5) axis('off'); text(0.2,0.95,'为祖国而学习，为人民而学习，为自己而学习！','sc'); text(0.2,0.8,'DTMF接收窗口','sc'); text(0.2,0.6,'此次接受到的数字或字符为:','sc'); text(0.2,0.4,'当前噪声大小为：','sc'); text(0.7,0.4,num2str(sigma),'sc'); switch Data case 1 if k==Data text(0.7,0.6,'1','sc');else text(0.7,0.6,'通信不成功！','sc');end case 2 if k==Data text(0.7,0.6,'2','sc');else text(0.7,0.6,'通信不成功！','sc');end case 3 if k==Data text(0.7,0.6,'3','sc');else text(0.7,0.6,'通信不成功！','sc');end case 4 if k==Data text(0.7,0.6,'A','sc');else text(0.7,0.6,'通信不成功！','sc');end case 5 if k==Data text(0.7,0.6,'4','sc');else text(0.7,0.6,'通信不成功！','sc');end case 6 if k==Data text(0.7,0.6,'5','sc');else text(0.7,0.6,'通信不成功！','sc');end case 7 if k==Data text(0.7,0.6,'6','sc');else text(0.7,0.6,'通信不成功！','sc');end case 8 if k==Data text(0.7,0.6,'B','sc');else text(0.7,0.6,'通信不成功！','sc');end case 9 if k==Data text(0.7,0.6,'7','sc');else text(0.7,0.6,'通信不成功！','sc');end case 10 if k==Data text(0.7,0.6,'8','sc');else text(0.7,0.6,'通信不成功！','sc');end case 11 if k==Data text(0.7,0.6,'9','sc');else text(0.7,0.6,'通信不成功！','sc');end case 12 if k==Data text(0.7,0.6,'C','sc');else text(0.7,0.6,'通信不成功！','sc');end case 13 if k==Data text(0.7,0.6,'*','sc');else text(0.7,0.6,'通信不成功！','sc');end case 14 if k==Data text(0.7,0.6,'0','sc');else text(0.7,0.6,'通信不成功！','sc');end case 15 if k==Data text(0.7,0.6,'#','sc');else text(0.7,0.6,'通信不成功！','sc');end case 16 if k==Data text(0.7,0.6,'D','sc');else text(0.7,0.6,'通信不成功！','sc');end otherwise text(0.7,0.6,'通信不成功！','sc'); end %end %======================================子程序结束==============================