数字通信技术实验报告

1、精选优质文档-倾情为你奉上实验一：clear allx,fs,bits=wavread('myheart.wav');z=sign(x); Max=max(abs(x); x1=abs(x/Max); Q=2048*x1;Y=zeros(length(x1),8);for m=1:length(x) if Q(m)>128 & Q(m)<2048 Y(m,2)=1; end if (Q(m)>32 & Q(m)<128) | (Q(m)>512 & Q(m)<2048) Y(m,3)=1; end if (Q(m)&g

2、t;16 & Q(m)<31) | (Q(m)>64 & Q(m)<128) | (Q(m)>256 & Q(m)<512) | (Q(m)>1024 & Q(m)<2048) Y(m,4)=1; end if z(m)>0 Y(m,1)=1; elseif z(m)<0 Y(m,1)=0; endendN=zeros(1,length(x1);for m=1:length(x1) N(m)=Y(m,2)*4+Y(m,3)*2+Y(m,4)+1;enda=0,16,32,64,128,256,512,1024

3、;b=1,1,2,4,8,16,32,64;for m=1:length(x1) q=ceil(Q(m)-a(N(m)/b(N(m); if q=0 Y(m,(5:8)=0,0,0,0; else k=num2str(dec2bin(q-1,4); Y(m,5)=str2num(k(1); Y(m,6)=str2num(k(2); Y(m,7)=str2num(k(3); Y(m,8)=str2num(k(4); endEnd实验结果：Max =0.3906a =Columns 1 through 7 0 16 32 64 128 256 512Column 8 1024b = 1 1 2 4

4、 8 16 32 64bits =16fs =22050k =m =q =476实验二：RGB=imread('8.jpg');I=rgb2gray(RGB);J=dct2(I);imshow(log(abs(J),),colormap(jet(64),colorbarJ(abs(J)<10)=0;K=idct2(J);figure,imshow(I)figure,imshow(K,0 255)原图像经过离散余弦变换后原图像的灰度图像经反变换后的图像：2.输入DCT进行JPEG图像压缩的代码如下：RGB=imread('8.jpg');I=rgb2gray

5、(RGB);I=im2double(I); T=dctmtx(8); B=blkproc(I,8 8,'P1*x*P2',T,T'); Mask= 1 1 1 1 0 0 0 0 1 1 1 0 0 0 0 0 1 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0; B2=blkproc(B,8 8,' P1*x',Mask); I2= blkproc(B2,8,8,'P1*x*P2',T',T

6、); Subplot(1,2,1); Imshow(I);title('原图像'); Subplot(1,2,2); Imshow(I2);title('压缩图像');3.游程编码：image1=imread('lena.jpg');imshow(image1);image2=image1(:);image2length=length(image2);for i=1:1:image2length if image2(i)>=127 image2(i)=255; else image2(i)=0; endendimage3=reshape(i

7、mage2,512,512);figure,imshow(image3);X=image3(:);x=1:1:length(X);figure,plot(x,X(x);j=1;image4(1)=1;for z=1:1:(length(X)-1) if X(z)=X(z+1) image4(j)=image4(j)+1; else data(j)=X(z); j=j+1; image4(j)=1; endenddata(j)=X(length(X);image4length=length(image4);y=1:1:image4length ;figure,plot(y,image4(y);C

8、R=image2length/image4length;实验三function code = addfade(modcode,Tf,isperiod,isfade)%功能：向传输序列modcode叠加衰落性信道的衰落参数k(t)if(isfade=1) if(isperiod=1) a=31; b=30+10*Tf; modcode(1,a:b)=0.1*modcode(1,a:b);end code=modcode; else code=modcode; endfunction bitcoded = channelcoding(sym,G,k)A=vec2mat(sym,k);%把向量转换成

9、矩阵U=A*G;U=mod(U,2);bitcoded=reshape(U',1,);function bitdecoded = channeldecoding(recode,Etab,Smatrix,H,n,k)%前向纠错函数，实现纠错功能row=length(recode)/n;E=zeros(row,n);RM=zeros(row,n);%纠错之后的矩阵R=vec2mat(recode,n);S=R*H'%伴随矩阵S=mod(S,2);for i=1:rowfor j=1:2(n-k)%查表纠错if(S(i,:)=Smatrix(j,:)E(i,:)=Etab(j,:);

10、RM(i,:)=R(i,:)+E(i,:);RM(i,:)=mod(RM(i,:),2);break;endendendbitdecoded=reshape(RM',1,);%转化为比特流ticclc%功能：有无信道编码性能比较M=2;%进制b=log2(M);%每符号比特数n=128*10000;%符号数G=1 1 1 1 0 0 0;1 0 1 0 1 0 0;0 1 1 0 0 1 0;1 1 0 0 0 0 1;%生成矩阵H=1 0 0 1 1 0 1;0 1 0 1 0 1 1;0 0 1 1 1 1 0;%监督矩阵Etab=0 0 0 0 0 0 0;0 0 0 0 0 0

11、 1;0 0 0 0 0 1 0;0 0 0 0 1 0 0;0 0 0 1 0 0 0;0 0 1 0 0 0 0;0 1 0 0 0 0 0;1 0 0 0 0 0 0;%错误图样Smatrix=Etab*H'%对应的伴随式sym=randint(n,1,M);sym=de2bi(sym,'left-msb');bitcoded=channelcoding(sym,G,4);modbit=pskmod(bitcoded,M);%在传输序列modbit加入AWGN噪声snr=0:0.2:15;%噪声为0到15dL=length(snr)%模拟信源编码%信道编码，（7,

12、4）码ser=zeros(1,L);ser2=zeros(1,L);for k=1:Ly=awgn(modbit,10*log10(b)+snr(k),'measured');zsym=pskdemod(y,M);%复数解调zbit=de2bi(zsym,'left-msb');recode=reshape(zbit',1,);Rstream=recode;err=(Rstream=bitcoded);errnum=sum(err);ser(k)=log10(errnum/length(bitcoded);%纠错bitdecoded=channeldec

13、oding(Rstream,Etab,Smatrix,H,7,4);err=(bitdecoded=bitcoded);errbits=sum(err);ser2(k)=log10(errbits/(length(bitcoded);endplot(snr,ser,'b-*')hold onplot(snr,ser2,'r-o')grid onlegend('没有信道编码','信道编码');xlabel('Eb/No(dB)');ylabel('SER');title('2PSK有无信道编码

14、性能比较');toc%clc;clear;close all;n=10000;b=randint(1,n);f1=1;f2=2;t=0:1/30:1-1/30;%ASKsa1=sin(2*pi*f1*t);E1=sum(sa1.2);sa1=sa1/sqrt(E1); %unit energy sa0=0*sa1;%FSKsf0=sin(2*pi*f1*t);E=sum(sf0.2);sf0=sf0/sqrt(E);sf1=sin(2*pi*f2*t);E=sum(sf1.2);sf1=sf1/sqrt(E);%PSKsp0=-sin(2*pi*f1*t)/sqrt(E1);sp1=s

15、in(2*pi*f1*t)/sqrt(E1);%调制ask=;psk=;fsk=;for i=1:n if b(i)=1 ask=ask sa1; psk=psk sp1; fsk=fsk sf1; else ask=ask sa0; psk=psk sp0; fsk=fsk sf0; endendfigure(1)subplot(411)stairs(0:10,b(1:10) b(10),'linewidth',1.5)axis(0 10 -0.5 1.5)title('Message Bits');grid onsubplot(412)tb=0:1/30:1

16、0-1/30;plot(tb, ask(1:10*30),'b','linewidth',1.5)title('ASK Modulation');grid onsubplot(413)plot(tb, fsk(1:10*30),'r','linewidth',1.5)title('FSK Modulation');grid onsubplot(414)plot(tb, psk(1:10*30),'k','linewidth',1.5)title('PSK Mo

17、dulation');grid onxlabel('Time');ylabel('Amplitude')%AWGNfor snr=0:30 askn=awgn(ask,snr); pskn=awgn(psk,snr); fskn=awgn(fsk,snr); %DETECTION A=;F=;P=; for i=1:n %ASK Detection if sum(sa1.*askn(1+30*(i-1):30*i)>0.5 A=A 1; else A=A 0; end %FSK Detection if sum(sf1.*fskn(1+30*(i-

18、1):30*i)>0.5 F=F 1; else F=F 0; end %PSK Detection if sum(sp1.*pskn(1+30*(i-1):30*i)>0 P=P 1; else P=P 0; end end %BER errA=0;errF=0; errP=0; for i=1:n if A(i)=b(i) errA=errA; else errA=errA+1; end if F(i)=b(i) errF=errF; else errF=errF+1; end if P(i)=b(i) errP=errP; else errP=errP+1; end end

19、BER_A(snr+1)=errA/n; BER_F(snr+1)=errF/n; BER_P(snr+1)=errP/n;endfigure(2)subplot(411)stairs(0:10,b(1:10) b(10),'linewidth',1.5)axis(0 10 -0.5 1.5);grid ontitle('Received signal after AWGN Channel')subplot(412)tb=0:1/30:10-1/30;plot(tb, askn(1:10*30),'b','linewidth',1

20、.5)title('Received ASK signal');grid onsubplot(413)plot(tb, fskn(1:10*30),'r','linewidth',1.5)title('Received FSK signal');grid onsubplot(414)plot(tb, pskn(1:10*30),'k','linewidth',1.5)title('Received PSK signal');grid onfigure(3)semilogy(0:30,

21、BER_A, 'b','linewidth',2)title('BER Vs SNR')grid on;hold onsemilogy(0:30,BER_F,'r','linewidth',2)semilogy(0:30,BER_P, 'k','linewidth',2)xlabel('Eo/No(dB)')ylabel('BER')hold offlegend('ASK','FSK','PSK');实验

22、四clcclear%Generationofbitpatterns=round(rand(1,25);signal=;%Generating20bitscarrier=;t=0:2*pi/119:2*pi;for k=1:25 %Creating60samplesforonecosine if s(1,k)=0 sig=-ones(1,120); %120minusonesforbit0 %120onesforbit1 else sig=ones(1,120); end c=cos(t); carrier=carrier c; signal=signal sig;endsubplot(4,1,

23、1);plot(signal);axis(-100 3100 -1.5 1.5);title('bfit Original Bit Sequence');%BPSKModulationofthesignalbpsk_sig=signal.*carrier;subplot(4,1,2);%Modulatingthesignalplot(bpsk_sig)axis(-100 3100 -1.5 1.5);title('bfit BPSK Modulated Signal');%Preparationof6newcarrierfrequenciest1=0:2*pi/

24、9:2*pi;t2=0:2*pi/19:2*pi;t3=0:2*pi/29:2*pi;t4=0:2*pi/39:2*pi;t5=0:2*pi/59:2*pi;t6=0:2*pi/119:2*pi;c1=cos(t1);c1=c1 c1 c1 c1 c1 c1 c1 c1 c1 c1 c1 c1;c2=cos(t2);c2=c2 c2 c2 c2 c2 c2;c3=cos(t3);c3=c3 c3 c3 c3;c4=cos(t4);c4=c4 c4 c4;c5=cos(t5);c5=c5 c5;c6=cos(t6);%Randomfrequencyhoppstoformaspreadsignalspread_signal=;for n=1:25 c=randint(1,1,1 6); switch(c) case(1) spread