数字通信技术实验报告Word文档格式.docx
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数字通信技术实验报告Word文档格式.docx
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Y(m,8)=str2num(k(4));
End
实验结果:
Max
=0.3906
a=
Columns
1
through
7
0163264128256
512
Column
8
1024
b=11248163264
bits
=16
fs
=22050
k
=111011011
m
=168873
q
=476
实验二:
RGB=imread('
8.jpg'
I=rgb2gray(RGB);
J=dct2(I);
imshow(log(abs(J)),[]),colormap(jet(64)),colorbar
J(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:
I=im2double(I);
T=dctmtx(8);
B=blkproc(I,[8
8],'
P1*x*P2'
T,T'
Mask=[
0
11100000
11000000
10000000
00000000
0];
B2=blkproc(B,[8
P1*x'
Mask);
I2=
blkproc(B2,[8,8],'
T'
T);
Subplot(1,2,1);
Imshow(I);
title('
原图像'
Subplot(1,2,2);
Imshow(I2);
压缩图像'
3.游程编码:
image1=imread('
lena.jpg'
imshow(image1);
image2=image1(:
image2length=length(image2);
fori=1:
1:
image2length
ifimage2(i)>
=127
image2(i)=255;
else
image2(i)=0;
image3=reshape(image2,512,512);
figure,imshow(image3);
X=image3(:
x=1:
length(X);
figure,plot(x,X(x));
j=1;
image4
(1)=1;
forz=1:
(length(X)-1)
ifX(z)==X(z+1)
image4(j)=image4(j)+1;
data(j)=X(z);
j=j+1;
image4(j)=1;
data(j)=X(length(X));
image4length=length(image4);
y=1:
image4length;
figure,plot(y,image4(y));
CR=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);
code=modcode;
bitcoded
channelcoding(sym,G,k)
A=vec2mat(sym,k);
%把向量转换成矩阵
U=A*G;
U=mod(U,2);
bitcoded=reshape(U'
1,[]);
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);
i=1:
row
j=1:
2^(n-k)
%查表纠错
if(S(i,:
)==Smatrix(j,:
))
E(i,:
)=Etab(j,:
RM(i,:
)=R(i,:
)+E(i,:
)=mod(RM(i,:
),2);
break;
bitdecoded=reshape(RM'
%转化为比特流
tic
clc
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
0;
1];
%生成矩阵
H=[1
1;
%监督矩阵
Etab=[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
到
15d
L=length(snr)
%模拟信源编码
%信道编码,(7,4)码
ser=zeros(1,L);
ser2=zeros(1,L);
k=1:
L
y=awgn(modbit,10*log10(b)+snr(k),'
measured'
zsym=pskdemod(y,M);
%复数解调
zbit=de2bi(zsym,'
recode=reshape(zbit'
Rstream=recode;
err=(Rstream~=bitcoded);
errnum=sum(err);
ser(k)=log10(errnum/length(bitcoded));
%纠错
bitdecoded=channeldecoding(Rstream,Etab,Smatrix,H,7,4);
err=(bitdecoded~=bitcoded);
errbits=sum(err);
ser2(k)=log10(errbits/(length(bitcoded)));
plot(snr,ser,'
b-*'
)
hold
on
plot(snr,ser2,'
r-o'
grid
legend('
没有信道编码'
'
信道编码'
xlabel('
Eb/No(dB)'
ylabel('
SER'
2PSK
有无信道编码性能比较'
toc
%
clc;
clear;
close
all;
n=10000;
b=randint(1,n);
f1=1;
f2=2;
t=0:
1/30:
1-1/30;
%ASK
sa1=sin(2*pi*f1*t);
E1=sum(sa1.^2);
sa1=sa1/sqrt(E1);
%unit
energy
sa0=0*sa1;
%FSK
sf0=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);
%PSK
sp0=-sin(2*pi*f1*t)/sqrt(E1);
sp1=sin(2*pi*f1*t)/sqrt(E1);
%调制
ask=[];
psk=[];
fsk=[];
n
b(i)==1
ask=[ask
sa1];
psk=[psk
sp1];
fsk=[fsk
sf1];
sa0];
sp0];
sf0];
figure
(1)
subplot(411)
stairs(0:
10,[b(1:
10)
b(10)],'
linewidth'
1.5)
axis([0
10
-0.5
1.5])
Message
Bits'
subplot(412)
tb=0:
10-1/30;
plot(tb,
ask(1:
10*30),'
b'
ASK
Modulation'
subplot(413)
fsk(1:
r'
FSK
subplot(414)
psk(1:
k'
PSK
Time'
Amplitude'
%AWGN
30
askn=awgn(ask,snr);
pskn=awgn(psk,snr);
fskn=awgn(fsk,snr);
%DETECTION
A=[];
F=[];
P=[];
%ASK
Detection
sum(sa1.*askn(1+30*(i-1):
30*i))>
0.5
A=[A
%FSK
sum(sf1.*fskn(1+30*(i-1):
F=[F
%PSK
sum(sp1.*pskn(1+30*(i-1):
P=[P
%BER
errA=0;
errF=0;
errP=0;
A(i)==b(i)
errA=errA;
errA=errA+1;
F(i)==b(i)
errF=errF;
errF=errF+1;
P(i)==b(i)
errP=errP;
errP=errP+1;
BER_A(snr+1)=errA/n;
BER_F(snr+1)=errF/n;
BER_P(snr+1)=errP/n;
figure
(2)
1.5]);
Received
signal
after
Channel'
askn(1:
signal'
fskn(1:
pskn(1:
figure(3)
semilogy(0:
30,BER_A,
'
2)
BER
Vs
SNR'
on;
30,BER_F,'
30,BER_P,
Eo/No(dB)'
BER'
off
ASK'
FSK'
PSK'
实验四
clear
%Generationofbitpattern
s=round(rand(1,25));
signal=[];
%Generating20bits
carrier=[];
t=[0:
2*pi/119:
2*pi];
25
%Creating60samplesforonecosine
s(1,k)==0
sig=-ones(1,120);
%120minusonesforbit0
%120onesforbit1
sig=ones(1,120);
c=cos(t);
carrier=[carrier
c];
signal=[signal
sig];
subplot(4,1,1);
plot(signal);
axis([-100
3100
-1.5
\bf\it
Original
Bit
Sequence'
%BPSKModulationofthesignal
bpsk_sig=signal.*carrier;
subplot(4,1,2);
%Modulatingthesignal
plot(bpsk_sig)
BPSK
Modulated
Signal'
%Preparationof6newcarrierfrequencies
t1=[0:
2*pi/9:
t2=[0:
2*pi/19:
t3=[0:
2*pi/29:
t4=[0:
2*pi/39:
t5=[0:
2*pi/59:
t6=[0:
c1=cos(t1);
c1=[c1
c1
c1];
c2=cos(t2);
c2=[c2
c2
c2];
c3=cos(t3);
c3=[c3
c3
c3];
c4=cos(t4);
c4=[c4
c4
c4];
c5=cos(t5);
c5=[c5
c5];
c6=cos(t6);
%Randomfrequencyhoppstoformaspreadsignal
spread_signal=[];
n=1:
c=randint(1,1,[1
6]);
switch(c)
case
(1)
spread_signal=[spread_signal
case
(2)
case(3)
case(4)
case(5)
case(6)
c6];
subplot(4,1,3)
plot([1:
3000],spread_signal);
Spread
Signal
with
6
frequencies'
%SpreadingBPSKSignalintowiderbandwithtotalof12frequencies
freq_hopped_sig=bpsk_sig.*spread_signal;
subplot(4,1,4)
3000],freq_hopped_sig);
Frequency
Hopped
Spectrum
%ExpressingtheFFTs
figure,subplot(2,1,1)
and
its
FFT'
subplot(2,1,2);
3000],abs(fft(freq_hopped_sig)));
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