代码

clcclearall%---------扩频通信过程---------------%---------只仿真一个频点的情况---------------%---------初始化---------------Ts=0.00001;fs=1/Ts;EndTime=2-Ts;%2s%---------产生信息序列(双极性不归零码)---------------Tm=0.25;fm=1/Tm;%码率[u,time]=gensig('square',2*Tm,EndTime,Ts);y=2*(u-0.5);figure(1);plot(time,y);title('信息序列');xlabel('time(seconds)');axis([02-22]);%---------FSK调制---------------T0=0.1;f0=1/T0;T1=0.2;f1=1/T1;[u0,time]=gensig('sin',T0,EndTime,Ts);[u1,time]=gensig('sin',T1,EndTime,Ts);y0=u0.*sign(-y+1);y1=u1.*sign(y+1);SignalFSK=y0+y1;%FSK信号%---------FSK调制的频谱---------------nfft=fs+1;Y=fft(SignalFSK,nfft);PSignalFSK=Y.*conj(Y)/nfft;f=fs*(0:nfft/2)/nfft;figure(2);plot(f,PSignalFSK(1:nfft/2+1));title('FSK调制后的频谱');xlabel('frequency(Hz)');axis([0100-infinf]);%---------FSK调制后，低通滤波---------------cof_low=fir1(64,25/fs);SignalFSK_l=filter(cof_low,1,SignalFSK);figure(3);plot(time,SignalFSK_l);title('FSK调制后经过低通滤波的波形');xlabel('time(seconds)');axis([02-22]);YSignalFSK_l=fft(SignalFSK_l,nfft);PSignalFSK_l=YSignalFSK_l.*conj(YSignalFSK_l)/nfft;f=fs*(0:nfft/2)/nfft;figure(4);plot(f,PSignalFSK_l(1:nfft/2+1));title('FSK调制后经过低通滤波的频谱');xlabel('frequency(Hz)');axis([0100-infinf]);%---------混频--------------fc=1000;Tc=1/fc;%频点:1000[Carrier,time]=gensig('sin',Tc,EndTime,Ts);%产生扩频载波MixSignal=SignalFSK_l.*Carrier;figure(6);plot(time,MixSignal);title('混频后的波形');xlabel('time(seconds)');axis([02-22]);%---------带通滤波--------cof_band=fir1(64,[fc-12.5,fc+12.5]/fs);yMixSignal=filter(cof_band,1,MixSignal);figure(7);plot(time,yMixSignal);title('经过带通滤波的混频信号');xlabel('time(seconds)');axis([02-22]);YMixSignal=fft(yMixSignal,nfft);PMixSignal=YMixSignal.*conj(YMixSignal)/nfft;f=fs*(0:nfft/2)/nfft;figure(8);plot(f,PMixSignal(1:nfft/2+1));title('经过带通滤波的混频信号频谱');xlabel('frequency(Hz)');axis([8001200-infinf]);%----------传输信道--------------Sign_send=yMixSignal;Sign_rec=Sign_send;%----------传输信道---------------%----------接收端---------------%----------解扩----------------fc=1000;Tc=1/fc;[Carrier,time]=gensig('sin',Tc,EndTime,Ts);%产生扩频载波Sign_rec=Sign_send;ySign_rec=Sign_rec.*Carrier;figure(9);plot(time,ySign_rec);title('解扩后的信号');xlabel('time(seconds)');axis([02-11]);%----------低通滤波,取下边频------------yrr=ySign_rec;cof_low=fir1(64,25/fs);Sign_rec_l=filter(cof_low,1,ySign_rec);figure(10);plot(time,Sign_rec_l);title('解扩后的下边频的信号');xlabel('time(seconds)');axis([02-11]);YSign_rec_l=fft(Sign_rec_l,nfft);PSign_rec_l=YSign_rec_l.*conj(YSign_rec_l)/nfft;f=fs*(0:nfft/2)/nfft;figure(11);plot(f,PSign_rec_l(1:nfft/2+1));title('解扩后的下边频频谱');xlabel('frequency(Hz)');axis([0100-infinf]);%----------FSK译码--------------cof_f0=fir1(64,[f0-0.25,f0+0.25]/fs);cof_f1=fir1(64,[f1-0.25,f1+0.25]/fs);DeFSK0=filter(cof_f0,1,Sign_rec_l);DeFSK1=filter(cof_f1,1,Sign_rec_l);rDeFSK0=DeFSK0.*u0;rDeFSK1=DeFSK1.*u1;rDeFSK=rDeFSK0-rDeFSK1;figure(12);plot(time,rDeFSK);title('采样判决前的信号');xlabel('time(seconds)');axis([02-22]);%-----------采样判决---------------Sampletime=0.25/Ts;Message=[];Num=0;while(Num2/Ts)if(mod(Num,Sampletime)==0)Message=[Messageones(1,Sampletime+1)*sign(sum(rDeFSK((Num+1):(Num+Sampletime))))];endNum=Num+Sampletime;endfigure(13);plot((1:length(Message))/fs,Message);title('恢复的信息');xlabel('time(seconds)');axis([02-22]);%---------产生8位m序列，控制频率合成器产生频率变化的高频载波---------------clearall;clc;%---------初始化---------------MAXCLOCK=1000000;%步长是0.01msPNSeq=[00000001];PNSeq1=[00010011];InitialPNSeq=PNSeq;InitialPNSeq1=PNSeq1;PNSeqNum=1;%第几次选择频率SaveFrq=[];SaveFrq1=[];%---------主仿真时钟---------------CLOCK=0;%单位是ms/100step=5000;%每100表示1ms%---------产生M序列---------------sim('SimCreatMSeq');%---------仿真开始---------------whileCLOCKMAXCLOCKCLOCK=CLOCK+step;Ifmod(CLOCK,5000)==0%---------产生M序列---------------%5ms跳一次频,每秒200跳%---------选择频率---------------MixFrq=SelectFrq(PNSeq(PNSeqNum:PNSeqNum+7))/1000e3;MixFrq1=SelectFrq(PNSeq1(PNSeqNum:PNSeqNum+7))/1000e3;PNSeqNum=PNSeqNum+1;SaveFrq=[SaveFrqMixFrq];SaveFrq1=[SaveFrq1MixFrq1];end%结果画图figure(20);fori=1:length(SaveFrq)plot(i/200,SaveFrq(i)/10,'s');plot(i/200,SaveFrq1(i)/10,'x');holdon;endtitle('跳频点的变化情况');xlabel('time(seconds)');ylabel('frequence(MHz)');axis([018990]);%---------根据m序列的8位状态，选择频率---------------FunctionFrq=SelectFrq(Code)tempCode=128*Code(8)+64*Code(7)+32*Code(6)+16*Code(5)+8*Code(4)+4*Code(3)+2*Code(2)+Code(1);if(tempCode200);tempCode=tempCode-128;endMaxFrq=94*1e6;MinFrq=88*1e6;Frq=(MaxFrq-MinFrq)/200*(tempCode-0)/2+MinFrq;%(MaxFrq-MinFrq)/200=30;