扩频通信仿真 源代码可以运行.doc

一个直序/跳频混合式扩频通信系统的仿真程序， % +直接序列扩频1+clear;clc;code_length=10;fs=4960; %每个信息码元内含fs个采样点t=0:1/fs:code_length;rand(seed,0);x=sign(rand(1,code_length)-0.5); %信息码for i=1:code_length s(1+(i-1)*fs):i*fs)=x(i);ends(i*fs+1)=x(i);figure(1);plot(t,s);axis(-0.5,code_length+0.5,-1.2,1.2);title(原始信息码);% +生成PN码+fd=1 0 0 1 0 1; %反馈系数num_mreg=length(fd)-1; %移位寄存器的个数num_mseq=2(num_mreg)-1; %一个m序列的码的个数init_mseq=ones(1,num_mreg);%m序列发生器初始化值mseq=zeros(1,num_mseq);for i=1:num_mreg mseq(i)=init_mseq(num_mreg-i+1);endi=i+1;for j=i:num_mseq for k=1:num_mreg if fd(k+1)=1 mseq(j)=xor(mseq(j),mseq(j-k); end endendfor i=1:num_mseq mseq(i)=sign(mseq(i)-0.5);endw_mseq=mseq;for i=1:code_length-1 w_mseq=w_mseq,mseq;endfor i=1:code_length*num_mseq c_mseq(i-1)*160+1):i*160)=w_mseq(i);endc_mseq(i*160+1)=w_mseq(i);figure(2);plot(t,c_mseq);axis(0,1,-1.1,1.1);title(一周期m序列);% +扩频+k_code=s.*c_mseq;figure(3);plot(t,k_code);axis(0,1,-1.1,1.1);title(扩频序列);% +跳频调制+fc0=3*fs/31;fc1=6*fs/31;fc2=9*fs/31;fc3=12*fs/31;tc=0:1/fs:159/fs;c0=2*cos(2*pi*fc0*tc);c0=c0,2*cos(2*pi*fc3*tc);c0=c0,2*cos(2*pi*fc1*tc);c0=c0,2*cos(2*pi*fc2*tc);c1=c0;for i=1:6 c1=c1,c0;endc1=c1,2*cos(2*pi*fc2*tc);c1=c1,2*cos(2*pi*fc3*tc);c1=c1,2*cos(2*pi*fc1*tc);c=c1;for i=1:code_length-1 c=c,c1;endc(code_length*fs+1)=0;signal=k_code.*c;figure(4);plot(t,signal);axis(100/fs,400/fs,-2.1,2.1);title(一个信息码元的跳频调制);% +解跳+signal_h=signal.*c;figure(5);plot(t,signal_h);axis(0,code_length,-4.1,4.1);title(一个信息码元的解跳);% +解扩+jk_code=signal_h.*c_mseq;figure(6);plot(t,jk_code);axis(0,code_length,-4.1,4.1);title(一个信息码元的解扩);% +低通滤波+wn=1/1e7;b=fir1(16,wn);H=freqz(b,1,16000);signal_d=filter(b,1,jk_code);figure(7);subplot(2,1,1);plot(t,signal_d);axis(0,code_length,-2.3,2