matlab仿真ask源程序3頁(yè)

1、clc;clear;%輸入二進(jìn)制信號(hào)N=10;xn=;x=1 0 1 1 0 0 1 0 1 0;t=0.0125:0.0125:N;y=cos(2*pi*100*t);for i=1:N if x(i)=1 xn(i*80-79:i*80)=ones(1,80); else xn(i*80-79:i*80)=zeros(1,80); endendsubplot(5,2,1)plot(xn);title(原始二進(jìn)制信號(hào));axis(0 800 -1 2)%載波波形y=cos(2*pi*2*t);subplot(5,2,2)plot(y);title(載波波形);axis(0 800 -2 2)

2、%載波調(diào)制z=xn.*y;subplot(5,2,3)plot(z)title(已調(diào)信號(hào))axis(0 800 -1.5 1.5)%對(duì)已調(diào)信號(hào)進(jìn)行頻譜分析ba=fft(z,512);ba=abs(ba);subplot(5,2,4)plot(ba);title(已調(diào)信號(hào)頻譜)axis(-200 600 0 150)%加入高斯噪聲a=0.1;%noise 系數(shù)，控制噪聲功率noise=a*(2*rand(1,80*N)-1);z1=z+noise;subplot(5,2,5)plot(z1);title(加入噪聲后信號(hào)波形);%對(duì)加噪信號(hào)進(jìn)行頻譜分析ba=fft(z1,512);ba=abs(b

3、a);subplot(5,2,6)plot(ba);title(加噪信號(hào)頻譜)axis(-200 600 0 150)%設(shè)計(jì)一個(gè)低通濾波器Wp =50/80; Ws = 70/80;n,Wn = buttord(Wp,Ws,1,5)b,a = butter(n,Wn);%對(duì)加入噪聲的信號(hào)進(jìn)行濾波x_fir=filter(b,1,z1); %觀察濾波之后的信號(hào)波形subplot(5,2,7)plot(x_fir);title(濾波之后的信號(hào))axis(0 800 -1.5 1.5)%相干解調(diào)x2=x_fir.*y;subplot(5,2,8);plot(x2);title(與相干載波相乘波形)axis(0 800 -0.5 2)%對(duì)加入噪聲的信號(hào)進(jìn)行濾波x3=filter(b,1,x2); subplot(5,2,9)plot(x3);title(與相干載波相乘后濾波波形 )axis(0 800 -0.5 2.5)%抽樣判決for i=1:N if abs(x3(i*80-20)=0.5; xn2(i*80-79:i*80)=ones(1,80); else xn2(i*80-79:i*80)=zeros(1,80); e