基于MATLAB仿真的數(shù)字信號調(diào)制的性能比較和分析

1、. 2ASK、2FSK、2PSK數(shù)字調(diào)制系統(tǒng)的Matlab實現(xiàn)及性能分析比較 指導(dǎo)教師: 班級： 學(xué)號： 姓名： . . 引言：數(shù)字信號有兩種傳輸方式，分別是基帶傳輸方式和調(diào)制傳輸方式，即帶通，在實際應(yīng)用中，因基帶信號含有大量低頻分量不利于傳送，所以必須經(jīng)過載波和調(diào)制形成帶通信號，通過數(shù)字基帶信號對載波某些參量進行控制，使之隨機帶信號的變化而變化，這這一過程即為數(shù)字調(diào)制。數(shù)字調(diào)制為信號長距離高效傳輸提供保障，現(xiàn)已廣泛應(yīng)用于生活和生產(chǎn)中。另外根據(jù)控制載波參量方式的不同，數(shù)字調(diào)制主要有調(diào)幅（ASK），調(diào)頻(FSK)，調(diào)相(PSK) 三種基本形式。本次課題針對于二進制的2ASK、2FSK、2PSK進

2、行討論，應(yīng)用Matlab矩陣實驗室進行仿真，分析和修改，通過仿真系統(tǒng)生成一個人機交互界面，以利于仿真系統(tǒng)的操作。通過對系統(tǒng)的仿真，更加直觀的了解數(shù)字調(diào)制系統(tǒng)的性能及影響其性能的各種因素，以便于比較，評論和改進。 關(guān)鍵詞： 數(shù)字，載波，調(diào)制，2ASK，2FSK，2PSK，Matlab，仿真，性能，比較，分析 正文： 一 .數(shù)字調(diào)制與解調(diào)原理 1.1 2ASK （1）2ASK 2ASK就是把頻率、相位作為常量，而把振幅作為變量，信息比特是通過載波的幅度來傳遞的。由于調(diào)制信號只有0或1兩個電平，相乘的結(jié)果相當(dāng)于將載頻或者關(guān)斷，或者接通，它的實際意義是當(dāng)調(diào)制的數(shù)字信號時，傳輸載波；當(dāng)調(diào)制的數(shù)字信號為時

3、，不傳輸載波。 ?t,當(dāng)cosa?1A?表達式為： kcs(t)?ASK20，當(dāng)a?0 ?k. . 1.2 2FSK 2FSK可以看做是2個不同頻率的2ASK的疊加，其調(diào)制與解調(diào)方法與2ASK差不多，主要頻率F1和F2，不同的組合產(chǎn)生所要求的2FSK調(diào)制信號。 ?t,當(dāng)cosa?1A? 公式如下：k1s(t)?FSK2?t，當(dāng)a?Acos0? k2 . . 1.3 2PSK 2PSK以載波的相位變化為基準，載波的相位隨數(shù)字基帶序列信號的1或者0而改變，通常用已經(jīng)調(diào)制完的載波的0或者表示數(shù)據(jù)1或者0，每種相位與之一一對應(yīng)。 二數(shù)字調(diào)制技術(shù)的仿真實現(xiàn) 本課程設(shè)計需要借助MATLAB的M文件編程功能

4、，對2ASK.2PSK.2FSK進行調(diào)制與解調(diào)的設(shè)計，并繪制出調(diào)制與解調(diào)后的波形，誤碼率的情況分析，軟件仿真可在已有平臺上實現(xiàn)。 1.2ASK代碼主函數(shù) . . allclose allclear n=16; fc=1000000; bitRate=1000000; N=50; %noise=ti; noise=10; 生成二進制代碼signal=source(n,N); % 調(diào)制后信號transmittedSignal=askModu(signal,bitRate,fc,N);% 加噪聲signal1=gussian(transmittedSignal,noise);% configueSi

5、gnal=demoASK(signal1,bitRate,fc,n,N); source代碼 sendSignal=source(n,N)function sendSignal=randint(1,n) bit=; i=1:length(sendSignal) for sendSignal(i)=0if bit1=zeros(1,N); else bit1=ones(1,N); end bit=bit,bit1; end figure(1) ;on plot(1:length(bit),bit),title(transmitting of binary),grid axis(0,N*lengt

6、h(sendSignal),-2,2); end askModu代碼 function transmittedSignal=askModu(signal,bitRate,fc,N)%signal為輸入信號，bitrate為bit速率，fc調(diào)制信號頻率，N %signal=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=; i=1:length(signal)for transmittedSignal=tr

7、ansmittedSignal,signal(i)*c;. . end 畫調(diào)制圖figure(2) %plot(1:length(transmittedSignal),transmittedSignal);title(Modulation ;);grid onof ASK 畫頻譜實部figure(3)% m=0:length(transmittedSignal)-1; F=fft(transmittedSignal); );ASK_frequency-domain analysis realplot(m,abs(real(F),title( ;ongrid 畫頻譜虛部 %figure(4) %

8、plot(m,imag(F);title(ASK_frequency-domain analysis imag); %grid on; endCheckRatePe代碼 PeWrong=CheckRatePe(signal1,signal2,s)function rights=0; wrongs=0; ki=1:s-2for (signal1(ki)=signal2(ki) if rights=rights+1; else wrongs=wrongs+1; end end PeWrong=wrongs/(wrongs+rights); end demoASK代碼 bitstream=demoA

9、SK(receivedSignal,bitRate,fc,n,N) function num load signal1=receivedSignal; %? signal2=abs(signal1); %LPF,?2 signal3=filter(num1,1,signal2); %?3? IN=fix(length(num1)/2); bitstream=; LL=fc/bitRate*N; i=IN+LL/2; %?D? (i=0.5; i=i+LL; end . . figure(6) 接收波形 subplot(3,1,1); % plot(1:length(signal1),signa

10、l1);title(Wave of receiving ;);grid onterminal(including noise) 接收整流后波形 subplot(3,1,2);% ;);grid on plot(1:length(signal2),signal2);title(Wave of commutate 包絡(luò)檢波波形 subplot(3,1,3);% ;);grid on plot(1:length(signal3),signal3);title(Wave of LPF bit=; i=1:length(bitstream)for bitstream(i)=0if bit1=zeros(

11、1,N); else bit1=ones(1,N); end bit=bit,bit1; end 解調(diào)后的二進制波形 figure(7)% ;onbinary of receiving terminal),grid plot(bit),title( axis(0,N*length(bitstream),-2.5,2.5); end gussian代碼 %加高斯白噪聲 signal=gussian(transmittedSignal,noise)function signal=sqrt(2)*transmittedSignal; signal=awgn(signal,noise); figure

12、(5) plot(1:length(signal),signal); ;onWave including noise),grid title( endfsk主函數(shù)代碼 allclose allclear 二進制代碼長度n=16;% 1頻率f1=18000000;% 2f2=6000000;%頻率 速率bitRate=1000000;%bit 碼元寬度N=50;% %noise=ti; 家性噪聲大小noise=10;%. . 產(chǎn)生二進制代碼signal=source(n,N);% 調(diào)制transmittedSignal=fskModu(signal,bitRate,f1,f2,N);% 加噪聲s

13、ignal1=gussian(transmittedSignal,noise);% 解調(diào)configueSignal=demoFSK(signal1,bitRate,f1,f2,N);% source代碼%二進制信號產(chǎn)生函數(shù) sendSignal=source(n,N)function sendSignal=randint(1,n) bit=; i=1:length(sendSignal)for sendSignal(i)=0if bit1=zeros(1,N); else bit1=ones(1,N); end bit=bit,bit1; end figure(1) ;ontransmitt

14、ing of binary),grid plot(bit),title( axis(0,N*length(sendSignal),-2.5,2.5); end fskModu代碼%頻率調(diào)制函數(shù) transmittedSignal=fskModu(signal,bitRate,f1,f2,N)function t=linspace(0,1/bitRate,N); 1調(diào)制信號 c1=sin(2*pi*t*f1);% 2調(diào)制信號 c2=sin(2*pi*t*f2);% transmittedSignal=; 調(diào)制 i=1:length(signal)% for signal(i)=1 if tran

15、smittedSignal=transmittedSignal,c1; else transmittedSignal=transmittedSignal,c2; end end 畫調(diào)制后波形圖figure(2) % plot(1:length(transmittedSignal),transmittedSignal);title(Modulation ;);grid onof FSKfigure(3) %畫調(diào)制后頻譜圖 . . m=0:length(transmittedSignal)-1; F=fft(transmittedSignal); );ASK_frequency-domain an

16、alysis realplot(m,abs(real(F),title( ;ongrid end demoFSK代碼 bitstream=demoFSK(receivedSignal,bitRate,f1,f2,N) function num load signal1=receivedSignal; ，得到高通分量通過HPF signal2=filter(gaotong,1,signal1); % 整流 signal3=abs(signal2); % 通過低通，形成包絡(luò) signal3=filter(lowpass,1,signal3); % bitstream=; IN1=fix(lengt

17、h(lowpass)/2)+fix(length(gaotong)/2); %延遲時 間 bitstream1=; 的抽樣點數(shù)每個 LL=N; %bit i=IN1 +LL/2; 判決% while (i=0.5; i=i+LL; end bitstream1 figure(5) subplot(3,1,1); plot(1:length(signal1),signal1);title(Wave of receiving ;onterminal(including noise);grid subplot(3,1,2); ;);grid on plot(1:length(signal2),sig

18、nal2);title(After Passing HPF subplot(3,1,3); ;onLPFAfter Passing );grid plot(1:length(signal3),signal3);title( 得到低頻分量BPF signal4=filter(daitong,1,signal1); %通過 整流% signal5=abs(signal4); ，形成包絡(luò)通過LPF signal5=filter(lowpass,1,signal5); % 延遲時間 IN2=fix(length(lowpass)/2)+fix(length(daitong)/2); % bitstre

19、am2=; bit每個的的抽樣點數(shù) LL=N; % i=IN2 +LL/2; 判決 (i=0.5; i=i+LL;. . end bitstream2 figure(6) subplot(3,1,1); plot(1:length(signal1),signal1);title(Wave of receiving ;);grid onterminal(including noise) subplot(3,1,2); ;);grid on plot(1:length(signal4),signal4);title(After Passing BPF subplot(3,1,3); ;);grid

20、 onAfter Passing LPF plot(1:length(signal5),signal5);title( 判決% for i=1:min(length(bitstream1),length(bitstream2) (bitstream1(i)bitstream2(i)if bitstream(i)=1; else bitstream(i)=0; end end bitstream 接收端波形% bit=; i=1:length(bitstream) for bitstream(i)=0 if bit1=zeros(1,N); else bit1=ones(1,N); end bi

21、t=bit,bit1; end figure(7) ;onbinary of receiving terminal),grid plot(bit),title( axis(0,N*length(bitstream),-2.5,2.5); end CheckRatePe代碼 PeWrong=CheckRatePe(signal1,signal2,s)function rights=0; wrongs=0; ki=1:s-2for (signal1(ki)=signal2(ki)if rights=rights+1; else wrongs=wrongs+1;. . end end PeWrong

22、=wrongs/(wrongs+rights); end gussian代碼 signal=gussian(transmittedSignal,noise)function signal=sqrt(2)*transmittedSignal; signal=awgn(signal,noise); figure(4) );Adding Noise plot(1:length(signal),signal),title( ;on grid end2psk主函數(shù)代碼 allclose allclear 二進制碼長n=16;% 載波頻率fc=1000000;% 信息頻率bitRate=1000000;

23、碼寬N=50;% 信道加性噪聲大小noise=10;% 生成二進制代碼signal=source(n,N);transmittedSignal=bpskModu(signal,bitRate,fc,N);對信號進行調(diào)制并進行頻譜 分析 加信道噪聲signal1=gussian(transmittedSignal,noise)% 信號解調(diào)configueSignal=demoBPSK(signal1,bitRate,fc,n,N);% source代碼 sendSignal=source(n,N)function sendSignal=randint(1,n) bit=; i=1:length(

24、sendSignal) for sendSignal(i)=0 if bit1=zeros(1,N); else bit1=ones(1,N); end bit=bit,bit1; end figure(1) ;),grid plot(bit),title(transmitting of binaryon. . axis(0,N*length(sendSignal),-2.5,2.5); end bpskModu代碼 transmittedSignal=bpskModu(signal,bitRate,fc,N)function t=linspace(0,1/bitRate,N); c1=sin

25、(2*pi*t*fc); c2=sin(2*pi*t*fc + pi); transmittedSignal=; i=1:length(signal)for signal(i)=1if transmittedSignal=transmittedSignal,c1; else transmittedSignal=transmittedSignal,c2; end end 畫調(diào)制圖figure(2) % plot(1:length(transmittedSignal),transmittedSignal);title(Modulation ;);grid onof BPSK 畫頻譜圖figure(

26、3)% m=0:length(transmittedSignal)-1; F=fft(transmittedSignal); );BPSK_frequency-domain analysis realplot(m,abs(real(F),title( ;ongrid end CheckRatePe代碼 PeWrong=CheckRatePe(signal1,signal2,s)function rights=0; wrongs=0; ki=1:s-2for (signal1(ki)=signal2(ki)if rights=rights+1; else wrongs=wrongs+1; end

27、 end PeWrong=wrongs/(wrongs+rights);. . end demoBPSK代碼 bitstream=demoBPSK(receivedSignal,bitRate,fc,n,N) function 存儲的低通濾波用的數(shù)據(jù)讀取num load num % signal1=receivedSignal; t=linspace(0,1/bitRate,N); c=sin(2*pi*t*fc); signal=; i=1:n for signal=signal,c; end sin乘同頻同相% signal2=signal1.*signal; 3包絡(luò)檢波 signal3=

28、filter(num1,1,signal2); %LPF, 延遲時間%? IN=fix(length(num1)/2); bitstream=; LL=fc/bitRate*N; i=IN+LL/2; 判決%while (i=0; i=i+LL; end figure(5) 畫接收的包含噪聲的波形 subplot(3,1,1);% plot(1:length(signal1),signal1);title(Wave of receiving ;);grid onterminal(including noise) 相干解調(diào)波形 subplot(3,1,2);% plot(1:length(sig

29、nal2),signal2);title(After Multipling sin ;onFuction);grid 包絡(luò)檢波波形 subplot(3,1,3);% ;onWave of LPF);grid plot(1:length(signal3),signal3);title( bit=; i=1:length(bitstream) for bitstream(i)=0if bit1=zeros(1,N); else bit1=ones(1,N); end bit=bit,bit1; end 二進制接收信號波形 figure(6). . ;);grid binary of receivi

30、ng terminalon plot(bit);title( axis(0,N*length(bitstream),-2.5,2.5); endgussian代碼 signal=gussian(transmittedSignal,noise)function signal=sqrt(2)*transmittedSignal; signal=awgn(signal,noise); figure(4) ; plot(1:length(signal),signal),grid on ) title(Adding noiseend 三種調(diào)制方式的性能比較: ;PeRateload ;PeRateplo

31、ad 補償誤差% fpeask(15)=1e-3; fpefsk(9)=1e-3; fpepsk(24)=0.002; fpepsk(26)=1e-3; figure(1)semilogy(-6:length(fpeask)-7,fpeask,-6:length(fpefsk)-7,fpefsk,-30:le ;onngth(fpepsk)-31,fpepsk),grid );Analysis Of Bit Error Ratetitle( );,PSK,legend(ASKFSK );xlabel(r/dB );ylabel(Pe figure(2) ;onsemilogy(-6:length(fpefsk)-7,fpeask);grid );Bit E