擴(kuò)頻通信實(shí)驗(yàn)及完整代碼

《擴(kuò)頻通信》實(shí)驗(yàn)報(bào)告題目：擴(kuò)頻通信系統(tǒng)仿真指導(dǎo)教師：學(xué)號(hào)：姓名：專(zhuān)業(yè)：跳頻通信系統(tǒng)原理介紹跳頻擴(kuò)頻系統(tǒng)是用偽隨機(jī)碼序列構(gòu)成跳頻指令來(lái)控制頻率合成器，在多個(gè)頻率中進(jìn)行有選擇的頻移鍵控。與直擴(kuò)系統(tǒng)相比，調(diào)頻系統(tǒng)中的偽隨機(jī)序列并不是直接傳輸，而是用來(lái)選擇信道。調(diào)頻系統(tǒng)的組成框圖如下列圖所示：圖中，擴(kuò)頻調(diào)制器是一個(gè)上變頻器，擴(kuò)頻解調(diào)器是一個(gè)下變頻器。頻率合成器A和頻率合成器B分別為上變頻器和下變頻器提供本振信號(hào)，他們的輸出信號(hào)在調(diào)頻碼的控制下按照統(tǒng)一規(guī)律跳變。實(shí)驗(yàn)?zāi)康膶W(xué)習(xí)擴(kuò)頻通信系統(tǒng)技術(shù)理論根底及調(diào)頻序列擴(kuò)頻系統(tǒng)根本原理，并設(shè)計(jì)出跳頻擴(kuò)頻通信系統(tǒng)模型。此通信系統(tǒng)具體包括信源模塊、信息調(diào)制模塊、擴(kuò)頻碼產(chǎn)生模塊、擴(kuò)頻模塊、信道模塊、解擴(kuò)模塊、信息解調(diào)模塊。三、程序設(shè)計(jì)流程圖仿真環(huán)境本次擴(kuò)頻通信系統(tǒng)的仿真是用MATLABR2012a模擬實(shí)現(xiàn)的，用MATLAB編程來(lái)實(shí)現(xiàn)對(duì)擴(kuò)頻通信系統(tǒng)的仿真。模塊源代碼及仿真波形本系統(tǒng)主要包括信源發(fā)出的基帶信號(hào)、發(fā)送端產(chǎn)生的擴(kuò)頻碼〔PN碼〕、頻率合成器產(chǎn)生待調(diào)制的載頻信號(hào)、FSK調(diào)制、接收端產(chǎn)生的擴(kuò)頻碼、頻率合成器產(chǎn)生和發(fā)送端相同的載頻信號(hào)、FSK解調(diào)，其中頻率合成器產(chǎn)生的載頻信號(hào)頻率受到擴(kuò)頻碼的控制，本系統(tǒng)中由頻率合成器產(chǎn)生1000Hz、1050Hz、1150Hz三種頻率的載頻。調(diào)頻系統(tǒng)調(diào)制模塊A)%%產(chǎn)生信源輸出的信息序列〔雙極性不歸零碼〕Tm=0.25;fm=1/Tm;%碼率[u,time]=gensig('square',2*Tm,EndTime,Ts);y=2*(u-0.5);figure(1)plot(time,y);title('信源輸出的信息序列');xlabel('time(seconds)');axis([02-22]);B)%%FSK調(diào)制及頻譜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信號(hào)%%FSK調(diào)制的頻譜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調(diào)制后的頻譜');xlabel('frequency(Hz)');axis([0100-infinf]);C)%%FSK調(diào)制后，低通濾波cof_low=fir1(64,25/fs);SignalFSK_1=filter(cof_low,1,SignalFSK);figure(3)plot(time,SignalFSK_1);title('FSK調(diào)制后經(jīng)過(guò)低通濾波器的波形');xlabel('time(seconds)');axis([02-22]);YSignalFSK_1=fft(SignalFSK_1,nfft);PSignalFSK_1=YSignalFSK_1.*conj(YSignalFSK_1)/nfft;f=fs*(0:nfft/2)/nfft;figure(4);plot(f,PSignalFSK_1(1:nfft/2+1));title('FSK調(diào)制后經(jīng)過(guò)低通濾波的頻譜');xlabel('frequency(Hz)');axis([0100-infinf]);混頻模塊%%%混頻1fc1=1000;Tc=1/fc1;%頻點(diǎn)：1000[Carrier,time]=gensig('sin',Tc,EndTime,Ts);%產(chǎn)生擴(kuò)頻載波1MixSignal1=SignalFSK_1.*Carrier;%混頻2fc2=1050;Tc=1/fc2;%頻點(diǎn)：1050[Carrier,time]=gensig('sin',Tc,EndTime,Ts);%產(chǎn)生擴(kuò)頻載波2MixSignal2=SignalFSK_1.*Carrier;%混頻3fc3=1150;Tc=1/fc3;%頻點(diǎn)：1150[Carrier,time]=gensig('sin',Tc,EndTime,Ts);%產(chǎn)生擴(kuò)頻載波3MixSignal3=SignalFSK_1.*Carrier;figure(5)plot(time,MixSignal1,time,MixSignal2,'r',time,MixSignal3,'k');title('混頻后的波形');xlabel('time(seconds)');axis([02-22]);〔3〕帶通濾波cof_band=fir1(64,[fc1-12.5,fc1+12.5]/fs);yMixSignal=filter(cof_band,1,MixSignal1);cof_band=fir1(64,[fc2-12.5,fc2+12.5]/fs);yMixSignal2=filter(cof_band,1,MixSignal2);cod_band=fir1(64,[fc3-12.5,fc3+12.5]/fs);yMixSignal3=filter(cof_band,1,MixSignal3);figure(6)plot(time,yMixSignal,time,yMixSignal2,'r',time,yMixSignal3,'k');title('經(jīng)過(guò)帶通濾波的混頻信號(hào)');xlabel('time(seconds)');axis([02-22]);〔4〕解擴(kuò)模塊A〕%%接收端解擴(kuò)fc=1000;Tc=1/fc;[Carrier,time]=gensig('sin',Tc,EndTime,Ts);%產(chǎn)生擴(kuò)頻載波Sign_rec=Sign_send;ySign_rec=Sign_rec.*Carrier;figure(8);plot(time,ySign_rec);title('解擴(kuò)后的信號(hào)');xlabel('time(second)');axis([02-11]);B)%%低通濾波，取下邊頻yrr=ySign_rec;cof_low=fir1(64,25/fs);Sign_rec_1=filter(cof_low,1,ySign_rec);figure(9);plot(time,Sign_rec_1);title('解擴(kuò)后的下邊頻的信號(hào)');xlabel('time(seconds)');axis([02-11]);YSign_rec_1=fft(Sign_rec_1,nfft);PSign_rec_1=YSign_rec_1.*conj(YSign_rec_1)/nfft;f=fs*(0:nfft/2)/nfft;figure(10);plot(f,PSign_rec_1(1:nfft/2+1));title('解擴(kuò)后的下邊頻頻譜');xlabel('frequency(Hz)');axis([0100-infinf]);C)%%FSK解碼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_1);DeFSK1=filter(cof_f1,1,Sign_rec_1);rDeFSK0=DeFSK0.*u0;rDeFSK1=DeFSK1.*u1;rDeFSK=rDeFSK0-rDeFSK1;figure(11);plot(time,rDeFSK);title('抽樣判決前的信號(hào)');xlabel('time(seconds)');axis([02-22]);D〕%%抽樣判決Sampletime=0.25/Ts;Message=[];Num=0;while(Num<2/Ts)if(mod(Num,Sampletime)==0)Message=[Messageones(1,Sampletime+1)*sign(sum(rDeFSK(Num+1):(Num+Sampletime)))];endNum=Num+Sampletime;endfigure(12);plot((1:length(Message))/fs,Message);title('輸出端恢復(fù)的信息');xlabel('time(seconds)');axis([02-22]);六、附錄〔完整源代碼〕clcclearall%調(diào)頻通信過(guò)程%給出三個(gè)頻點(diǎn)，濾波后僅對(duì)第一個(gè)頻點(diǎn)進(jìn)行解擴(kuò)%初始化Ts=0.00001;fs=1/Ts;EndTime=2-Ts;%2s%%產(chǎn)生信源輸出的信息序列〔雙極性不歸零碼〕Tm=0.25;fm=1/Tm;%碼率[u,time]=gensig('square',2*Tm,EndTime,Ts);y=2*(u-0.5);figure(1)plot(time,y);title('信源輸出的信息序列');xlabel('time(seconds)');axis([02-22]);%%FSK調(diào)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信號(hào)%%FSK調(diào)制的頻譜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調(diào)制后的頻譜');xlabel('frequency(Hz)');axis([0100-infinf]);%%FSK調(diào)制后，低通濾波cof_low=fir1(64,25/fs);SignalFSK_1=filter(cof_low,1,SignalFSK);figure(3)plot(time,SignalFSK_1);title('FSK調(diào)制后經(jīng)過(guò)低通濾波器的波形');xlabel('time(seconds)');axis([02-22]);YSignalFSK_1=fft(SignalFSK_1,nfft);PSignalFSK_1=YSignalFSK_1.*conj(YSignalFSK_1)/nfft;f=fs*(0:nfft/2)/nfft;figure(4);plot(f,PSignalFSK_1(1:nfft/2+1));title('FSK調(diào)制后經(jīng)過(guò)低通濾波的頻譜');xlabel('frequency(Hz)');axis([0100-infinf]);%%%混頻1fc1=1000;Tc=1/fc1;%頻點(diǎn)：1000[Carrier,time]=gensig('sin',Tc,EndTime,Ts);%產(chǎn)生擴(kuò)頻載波1MixSignal1=SignalFSK_1.*Carrier;%混頻2fc2=1050;Tc=1/fc2;%頻點(diǎn)：1050[Carrier,time]=gensig('sin',Tc,EndTime,Ts);%產(chǎn)生擴(kuò)頻載波2MixSignal2=SignalFSK_1.*Carrier;%混頻3fc3=1150;Tc=1/fc3;%頻點(diǎn)：1150[Carrier,time]=gensig('sin',Tc,EndTime,Ts);%產(chǎn)生擴(kuò)頻載波3MixSignal3=SignalFSK_1.*Carrier;figure(5)plot(time,MixSignal1,time,MixSignal2,'r',time,MixSignal3,'k');title('混頻后的波形');xlabel('time(seconds)');axis([02-22]);%%帶通濾波cof_band=fir1(64,[fc1-12.5,fc1+12.5]/fs);yMixSignal=filter(cof_band,1,MixSignal1);cof_band=fir1(64,[fc2-12.5,fc2+12.5]/fs);yMixSignal2=filter(cof_band,1,MixSignal2);cod_band=fir1(64,[fc3-12.5,fc3+12.5]/fs);yMixSignal3=filter(cof_band,1,MixSignal3);figure(6)plot(time,yMixSignal,time,yMixSignal2,'r',time,yMixSignal3,'k');title('經(jīng)過(guò)帶通濾波的混頻信號(hào)');xlabel('time(seconds)');axis([02-22]);%%傳輸信道Sign_send=yMixSignal;Sign_rec=Sign_send;%%接收端解擴(kuò)fc=1000;Tc=1/fc;[Carrier,time]=gensig('sin',Tc,EndTime,Ts);%產(chǎn)生擴(kuò)頻載波Sign_rec=Sign_send;ySign_rec=Sign_rec.*Carrier;figure(8);plot(time,ySign_rec);title('解擴(kuò)后的信號(hào)');xlabel('time(second)');axis([02-11]);%%低通濾波，取下邊頻yrr=ySign_rec;cof_low=fir1(64,25/fs);Sign_rec_1=filter(cof_low,1,ySign_rec);figure(9);plot(time,Sign_rec_1);title('解擴(kuò)后的下邊頻的信號(hào)');xlabel('time(seconds)');axis([02-11]);YSign_rec_1=fft(Sign_rec_1,nfft);PSign_rec_1=YSign_rec_1.*conj(YSign_rec_1)/nfft;f=fs*(0:nfft/2)/nfft;figure(10);plot(f,PSign_rec_1(1:nfft/2+1)