CDMA.rar_cdma_解扩_解扩matlab程序_解扩程序_调制解调

%************************************************************************** %※ 星上数据接收端 ※% %************************************************************************** clc; clear all; close all; load send_data2; Rb=800000;%码元速率819.2k k=1; %一个码元间隔包括1个载波周期/2 k2=8; %采样率 fc=k*Rb; % 载波频率， fs=fc*k2; % 信号采样率 x_size=k*k2; %正交下变频 %A/D模数变换 % [recievdataI,recievdataQ]=QPSK_demodu(upsenddata); datalength=length(upsenddata); recievdataI=upsenddataI; recievdataQ=upsenddataQ; %FFT分路 %*******解扩不解调************% %产生本地载波恢复 carry_I(1:datalength)=cos(2*pi*fc*(1:datalength)/fs+pi/4); carry_Q(1:datalength)=sin(2*pi*fc*(1:datalength)/fs+pi/4); firstdemoduQ=recievdataQ.*carry_Q; %产生15位扩频短码 shortPNcode=shortcode(datalength/k2); % for var=1:channel %产生42位扩频长码 longPNcode(1,:)=longcode1(datalength/k2,1); %DSSoutdataI=mod(walshdata96I+longPNcode,2); %DSSoutdataQ=mod(walshdata96Q+longPNcode,2); %长短码进行摸2加，生成本地扰码 despreadcodeI(1,:)=mod(longPNcode(1,:)+shortPNcode(1,:),2); despreadcodeQ(1,:)=mod(longPNcode(1,:)+shortPNcode(2,:),2); %变为双极性码,0->1,1->-1 despreadcode1I(1,:)=-2*(despreadcodeI(1,:)-0.5); despreadcode1Q(1,:)=-2*(despreadcodeQ(1,:)-0.5); %对本地扰码进行8倍采样 for i=1:datalength/k2 despreadcode2I(1,1+(i-1)*k2:i*k2)=despreadcode1I(1,i); despreadcode2Q(1,1+(i-1)*k2:i*k2)=despreadcode1Q(1,i); end %解扩 despreadout1I(1,:)=recievdataI.*despreadcode2I(1,:); despreadout1Q(1,:)=recievdataQ.*despreadcode2Q(1,:); firdemdespreQ=firstdemoduQ.*despreadcode2Q(1,:); %% %解调 N=9; Wn=1/4; B = fir1(N,Wn); demoduoutI(1,:)=despreadout1I(1,:).*carry_I; demoduoutQ(1,:)=despreadout1Q(1,:).*carry_Q; demodudadaI(1,:)=filter2(B,demoduoutI(1,:));%filter2滤波器无延时,filter有延时 demodudataQ(1,:)=filter2(B,demoduoutQ(1,:)); demodudataI(1,k2/2+1:datalength)=demodudadaI(1,1:datalength-k2/2); %[demodudataI(var,:),demodudataQ(var,:)]=QPSK_demodu2(despreadout1I(var,:),despreadout1Q(var,:)); % demodudata1I(var,:)=filter2(B,demodudataI(var,:)); % demodudata1Q(var,:)=filter2(B,demodudataQ(var,:)); %8:1下采样,spreadtimes=24; k3=spreadtimes*k2; for i=1:datalength/k3 demodudata2I(1,i)=demodudataI(1,k3/2+1+k3*(i-1)); demodudata2Q(1,i)=demodudataQ(1,k3/2+1+k3*(i-1)); end % end %% *******************************% demodudata3I=-(sign(demodudata2I)-1)/2; demodudata3Q=-(sign(demodudata2Q)-1)/2; %*************星上交换**********% %CWTDM复接，去下行调制器 %% *******************************% figure(2) subplot(4,1,1) plot(despreadout1Q(1,:)) %axis([0 k3*8 -1.5 1.5]) axis([0 k3 -2 2]) title('输入解调信号') grid on subplot(4,1,2) plot(carry_Q(1,:)) axis([0 k3 -1 1]) title('载波信号') grid on subplot(4,1,3) plot(demoduoutQ(1,:)) axis([0 k3 -1 1]) title('解调输出信号') grid on subplot(4,1,4) plot(demodudataQ(1,:)) axis([0 k3 -1 1]) title('滤波输出信号') grid on figure(3) subplot(3,1,1) stairs(despreadcode1Q(1,:)) %axis([0 k3*8 -1.5 1.5]) axis([1 k3/8+1 -1.2 1.2]) title('despreadcode1Q') grid on subplot(3,1,2) plot(despreadcode2Q(1,:)) axis([0 k3 -2 2]) title('despreadcode2Q') grid on subplot(3,1,3) plot(recievdataQ(1,:)) axis([0 k3 -1.2 1.2]) title('recievdataQ') grid on figure(4) subplot(3,1,1) plot(despreadcode2Q(1,:)) %axis([0 k3*8 -1.5 1.5]) axis([0 k3 -2 2]) title('despreadcode1Q') grid on subplot(3,1,2) plot(firstdemoduQ(1,:)) axis([0 k3 -2 2]) title('firstdemoduQ') grid on subplot(3,1,3) plot(firdemdespreQ) axis([0 k3 -1.2 1.2]) title('firdemdespreQ') grid on % subplot(4,1,4) % plot(carry_Q(1,:)) % axis([0 k3*2 -1 1]) % title('解调输出信号') % grid on % %% % figure(4) % subplot(3,1,1) % plot(demoduoutQ(1,:)) % %axis([0 k3*8 -1.5 1.5]) % axis([0 k3*2 -1.2 1.2]) % title('解调输出信号demoduoutQ') % grid on % subplot(3,1,2) % plot(demodudataQ(1,:)) % axis([0 k3*2 -1 1]) % title('滤波输出信号demodudataQ') % grid on % subplot(3,1,3) % plot(demodudata2Q(1,:)) % axis([1 k3/4 -1 1]) % title('下采样输出信号demodudata2Q') % grid on % %% *******************************% % figure(3) % subplot(2,1,1) % % stairs(despreadout2I(1,:)) % % axis([1 k3/4 -1.2 1.2]) % % title('原始发送信号') % % grid on % % subplot(3,1,2) % stairs(demodudata3I(1,:)) % %axis([0 k3*8 -1.5 1.5]) % axis([1 k3/4 -0.2 1.2]) % title('解扩输出信号') % grid on % subplot(2,1,2) % stairs(walshdataI(1,:)) % axis([1 k3/4 -0.2 1.2]) % title('原始发送信号') % grid on