2ASK、2FSK、2PSK数字调制系统的Matlab实现及性能分析(总24页)

1、2ASK、2FSK、2PSK数字调制系统的Matlab实现及性能分析比较引言：数字信号有两种传输方式，分别是基带传输方式和调制传输方式，即带通，在实际应用中，因基带信号含有大量低频分量不利于传送，所以必须经过载波和调制形成带通信号，通过数字基带信号对载波某些参量进行控制，使之随机带信号的变化而变化，这这一过程即为数字调制。数字调制为信号长距离高效传输提供保障，现已广泛应用于生活和生产中。另外根据控制载波参量方式的不同，数字调制主要有调幅（ASK），调频(FSK)，调相(PSK) 三种基本形式。本次课题针对于二进制的2ASK、2FSK、2PSK进行讨论，应用Matlab矩阵实验室进行仿真，分析和

2、修改，通过仿真系统生成一个人机交互界面，以利于仿真系统的操作。通过对系统的仿真，更加直观的了解数字调制系统的性能及影响其性能的各种因素，以便于比较，评论和改进。 关键词： 数字，载波，调制，2ASK，2FSK，2PSK，Matlab，仿真，性能，比较，分析正文：一 .数字调制与解调原理1.1 2ASK（1）2ASK2ASK就是把频率、相位作为常量，而把振幅作为变量，信息比特是通过载波的幅度来传递的。由于调制信号只有0或1两个电平，相乘的结果相当于将载频或者关断，或者接通，它的实际意义是当调制的数字信号1时，传输载波；当调制的数字信号为0时，不传输载波。表达式为：1.2 2FSK2FSK可以看做

3、是2个不同频率的2ASK的叠加，其调制与解调方法与2ASK差不多，主要频率F1和F2，不同的组合产生所要求的2FSK调制信号。公式如下：1.3 2PSK2PSK以载波的相位变化为基准，载波的相位随数字基带序列信号的1或者0而改变，通常用已经调制完的载波的0或者表示数据1或者0，每种相位与之一一对应。二数字调制技术的仿真实现本课程设计需要借助MATLAB的M文件编程功能，对2ASK.2PSK.2FSK进行调制与解调的设计，并绘制出调制与解调后的波形，误码率的情况分析，软件仿真可在已有平台上实现。1.2ASK代码主函数close allclear alln=16;fc=1000000; bitRa

4、te=1000000;N=50;%noise=ti;noise=10;signal=source(n,N); %生成二进制代码transmittedSignal=askModu(signal,bitRate,fc,N);%调制后信号signal1=gussian(transmittedSignal,noise);%加噪声configueSignal=demoASK(signal1,bitRate,fc,n,N);source代码function sendSignal=source(n,N) sendSignal=randint(1,n) bit=; for i=1:length(sendSig

5、nal) if sendSignal(i)=0 bit1=zeros(1,N); else bit1=ones(1,N); end bit=bit,bit1; end figure(1) plot(1:length(bit),bit),title(transmitting of binary),grid on; axis(0,N*length(sendSignal),-2,2);endaskModu代码function transmittedSignal=askModu(signal,bitRate,fc,N)%signal为输入信号，bitrate为bit速率，fc调制信号频率，N %sig

6、nal=0 0 1 0 1 1 0 1;% bitRate=1000000;% fc=1000000;% N=32; t=linspace(0,1/bitRate,N); c=sin(2*pi*t*fc); transmittedSignal=; for i=1:length(signal) transmittedSignal=transmittedSignal,signal(i)*c; endfigure(2) %画调制图plot(1:length(transmittedSignal),transmittedSignal);title(Modulation of ASK);grid on;f

7、igure(3)%画频谱实部m=0:length(transmittedSignal)-1;F=fft(transmittedSignal);plot(m,abs(real(F),title(ASK_frequency-domain analysis real);grid on;%figure(4) 画频谱虚部%plot(m,imag(F);title(ASK_frequency-domain analysis imag);%grid on;endCheckRatePe代码function PeWrong=CheckRatePe(signal1,signal2,s)rights=0;wrong

8、s=0;for ki=1:s-2 if(signal1(ki)=signal2(ki) rights=rights+1; else wrongs=wrongs+1; endendPeWrong=wrongs/(wrongs+rights);enddemoASK代码function bitstream=demoASK(receivedSignal,bitRate,fc,n,N) load num signal1=receivedSignal; signal2=abs(signal1); % signal3=filter(num1,1,signal2); %LPF, IN=fix(length(n

9、um1)/2); % bitstream=; LL=fc/bitRate*N; i=IN+LL/2; while (i=0.5; i=i+LL; end figure(6) subplot(3,1,1); %接收波形 plot(1:length(signal1),signal1);title(Wave of receiving terminal(including noise);grid on; subplot(3,1,2);%接收整流后波形 plot(1:length(signal2),signal2);title(Wave of commutate);grid on; subplot(3,

10、1,3);%包络检波波形 plot(1:length(signal3),signal3);title(Wave of LPF);grid on; bit=; for i=1:length(bitstream) if bitstream(i)=0 bit1=zeros(1,N); else bit1=ones(1,N); end bit=bit,bit1; end figure(7)%解调后的二进制波形 plot(bit),title(binary of receiving terminal),grid on; axis(0,N*length(bitstream),-2.5,2.5);endgu

11、ssian代码 %加高斯白噪声function signal=gussian(transmittedSignal,noise) signal=sqrt(2)*transmittedSignal; signal=awgn(signal,noise); figure(5) plot(1:length(signal),signal); title(Wave including noise),grid on;endfsk主函数代码close allclear alln=16;%二进制代码长度f1=18000000;%频率1f2=6000000;%频率2bitRate=1000000;%bit速率N=5

12、0;%码元宽度%noise=ti;noise=10;%家性噪声大小signal=source(n,N);%产生二进制代码transmittedSignal=fskModu(signal,bitRate,f1,f2,N);%调制signal1=gussian(transmittedSignal,noise);%加噪声configueSignal=demoFSK(signal1,bitRate,f1,f2,N);%解调source代码%二进制信号产生函数function sendSignal=source(n,N) sendSignal=randint(1,n) bit=; for i=1:len

13、gth(sendSignal) if sendSignal(i)=0 bit1=zeros(1,N); else bit1=ones(1,N); end bit=bit,bit1; end figure(1) plot(bit),title(transmitting of binary),grid on; axis(0,N*length(sendSignal),-2.5,2.5);endfskModu代码%频率调制函数function transmittedSignal=fskModu(signal,bitRate,f1,f2,N) t=linspace(0,1/bitRate,N); c1=

14、sin(2*pi*t*f1);%调制信号1 c2=sin(2*pi*t*f2);%调制信号2 transmittedSignal=; for i=1:length(signal)%调制 if signal(i)=1 transmittedSignal=transmittedSignal,c1; else transmittedSignal=transmittedSignal,c2; end endfigure(2) %画调制后波形图 plot(1:length(transmittedSignal),transmittedSignal);title(Modulation of FSK);grid

15、 on;figure(3) %画调制后频谱图m=0:length(transmittedSignal)-1;F=fft(transmittedSignal);plot(m,abs(real(F),title(ASK_frequency-domain analysis real);grid on;enddemoFSK代码function bitstream=demoFSK(receivedSignal,bitRate,f1,f2,N) load num signal1=receivedSignal; signal2=filter(gaotong,1,signal1); %通过HPF，得到高通分量

16、 signal3=abs(signal2); %整流 signal3=filter(lowpass,1,signal3); %通过低通，形成包络 bitstream=; IN1=fix(length(lowpass)/2)+fix(length(gaotong)/2); %延迟时间 bitstream1=; LL=N; %每个bit的抽样点数 i=IN1 +LL/2; while (i=0.5; i=i+LL; end bitstream1 figure(5) subplot(3,1,1); plot(1:length(signal1),signal1);title(Wave of recei

17、ving terminal(including noise);grid on; subplot(3,1,2); plot(1:length(signal2),signal2);title(After Passing HPF);grid on; subplot(3,1,3); plot(1:length(signal3),signal3);title(After Passing LPF);grid on; signal4=filter(daitong,1,signal1); %通过BPF得到低频分量 signal5=abs(signal4); %整流 signal5=filter(lowpass

18、,1,signal5); %通过LPF，形成包络 IN2=fix(length(lowpass)/2)+fix(length(daitong)/2); %延迟时间 bitstream2=; LL=N; %每个bit的的抽样点数 i=IN2 +LL/2; while (i=0.5; i=i+LL; end bitstream2 figure(6) subplot(3,1,1); plot(1:length(signal1),signal1);title(Wave of receiving terminal(including noise);grid on; subplot(3,1,2); plo

19、t(1:length(signal4),signal4);title(After Passing BPF);grid on; subplot(3,1,3); plot(1:length(signal5),signal5);title(After Passing LPF);grid on; for i=1:min(length(bitstream1),length(bitstream2) %判决 if(bitstream1(i)bitstream2(i) bitstream(i)=1; else bitstream(i)=0; end end bitstream bit=; %接收端波形 for

20、 i=1:length(bitstream) if bitstream(i)=0 bit1=zeros(1,N); else bit1=ones(1,N); end bit=bit,bit1; end figure(7) plot(bit),title(binary of receiving terminal),grid on; axis(0,N*length(bitstream),-2.5,2.5); end CheckRatePe代码function PeWrong=CheckRatePe(signal1,signal2,s)rights=0;wrongs=0;for ki=1:s-2 i

21、f(signal1(ki)=signal2(ki) rights=rights+1; else wrongs=wrongs+1; endendPeWrong=wrongs/(wrongs+rights);endgussian代码function signal=gussian(transmittedSignal,noise) signal=sqrt(2)*transmittedSignal; signal=awgn(signal,noise); figure(4) plot(1:length(signal),signal),title(Adding Noise); grid on;end2psk

22、主函数代码close allclear alln=16;%二进制码长fc=1000000;%载波频率bitRate=1000000;信息频率N=50;%码宽noise=10;%信道加性噪声大小signal=source(n,N);生成二进制代码transmittedSignal=bpskModu(signal,bitRate,fc,N);对信号进行调制并进行频谱分析signal1=gussian(transmittedSignal,noise)%加信道噪声configueSignal=demoBPSK(signal1,bitRate,fc,n,N);%信号解调source代码function

23、sendSignal=source(n,N) sendSignal=randint(1,n) bit=; for i=1:length(sendSignal) if sendSignal(i)=0 bit1=zeros(1,N); else bit1=ones(1,N); end bit=bit,bit1; end figure(1) plot(bit),title(transmitting of binary),grid on; axis(0,N*length(sendSignal),-2.5,2.5);endbpskModu代码function transmittedSignal=bpsk

24、Modu(signal,bitRate,fc,N) t=linspace(0,1/bitRate,N); c1=sin(2*pi*t*fc); c2=sin(2*pi*t*fc + pi); transmittedSignal=; for i=1:length(signal) if signal(i)=1 transmittedSignal=transmittedSignal,c1; else transmittedSignal=transmittedSignal,c2; end endfigure(2) % 画调制图plot(1:length(transmittedSignal),trans

25、mittedSignal);title(Modulation of BPSK);grid on;figure(3)%画频谱图m=0:length(transmittedSignal)-1;F=fft(transmittedSignal);plot(m,abs(real(F),title(BPSK_frequency-domain analysis real);grid on;endCheckRatePe代码function PeWrong=CheckRatePe(signal1,signal2,s)rights=0;wrongs=0;for ki=1:s-2 if(signal1(ki)=si

26、gnal2(ki) rights=rights+1; else wrongs=wrongs+1; endendPeWrong=wrongs/(wrongs+rights);enddemoBPSK代码function bitstream=demoBPSK(receivedSignal,bitRate,fc,n,N) load num %读取num存储的低通滤波用的数据 signal1=receivedSignal; t=linspace(0,1/bitRate,N); c=sin(2*pi*t*fc); signal=; for i=1:n signal=signal,c; end signal

27、2=signal1.*signal; %乘同频同相sin signal3=filter(num1,1,signal2); %LPF,包络检波3 IN=fix(length(num1)/2); %延迟时间 bitstream=; LL=fc/bitRate*N; i=IN+LL/2; while (i=0; i=i+LL; end figure(5) subplot(3,1,1);%画接收的包含噪声的波形 plot(1:length(signal1),signal1);title(Wave of receiving terminal(including noise);grid on; subpl

28、ot(3,1,2);%相干解调波形 plot(1:length(signal2),signal2);title(After Multipling sin Fuction);grid on; subplot(3,1,3);%包络检波波形 plot(1:length(signal3),signal3);title(Wave of LPF);grid on; bit=; for i=1:length(bitstream) if bitstream(i)=0 bit1=zeros(1,N); else bit1=ones(1,N); end bit=bit,bit1; end figure(6)二进制

29、接收信号波形 plot(bit);title(binary of receiving terminal);grid on; axis(0,N*length(bitstream),-2.5,2.5);endgussian代码function signal=gussian(transmittedSignal,noise) signal=sqrt(2)*transmittedSignal; signal=awgn(signal,noise); figure(4) plot(1:length(signal),signal),grid on; title(Adding noise)end三种调制方式的性能比较:load PeRate;load PeRatep;%补偿误差fpeask(15)=1e-3;fpefsk(9)=1e-3;fpepsk(24)=0.002;fpepsk(26)=1e-3;fig