QPSK_matlab图像pluto通信原理_

clear close all % 参数设置 fs = 100e3; % 采样速率 sr = 5e3; % 码元速率 N=10000; ebno = 1000; cfo = -200; b=randi([0 1],1,N); bitData=b; nBytes =N* 1; nCode = 1; %一个字节用8个bit编码 totaldata=N/2+100; % 2. 进行交织 bitData_scramble = matintrlv(bitData, 10* nCode, nBytes / 10); %一个突发的错误变成随机错误，提升纠错能力 % 3. 映射为QPSK符号 symData = QPSKMap(bitData_scramble); % 添加训练符号 symData = [ones(1, 100), symData]; % 4. 调制 modData = pskmod(symData, 4, pi/4); figure(6) title('星座图'); scatter(real(modData),imag(modData)); % 5. 利用zc序列生成同步头 onePreData = CreatZC(500); preData = repmat(onePreData, 1, 2); preLength = length(preData); % 6. 添加导频纠正相偏 totalData = modData; % 7. 设置发射滤波器,也就是脉冲成型滤波器 irfn = 8;%；；滤波器截断的码元范围 ipoint = fs/sr;%每个码元范围内采样的点数 alfa = 0.5; % 由此可以得出带宽是10e3 * (1.5) = 15e3; sendFilter = rcosdesign(alfa, irfn, ipoint, 'sqrt'); delay = irfn * ipoint / 2; upData = upsample(totalData, ipoint);%进行上采样才能得到正确结果 toSend = conv(upData, sendFilter,'same'); %%%%%%%%%%%%%%%%pluto发送的数据要为列向量%%%%%%%%%%%%%%%%%%%% toSend=[preData toSend]; % toSend=toSend.'; Frame_len = length(toSend); % 计算信噪比系数 spow = mean(abs(toSend).^2); npow = 0.5 * spow ./ 10^(ebno / 10); attn = sqrt(npow); %频偏Hz % 计算信噪比系数 spow = mean(abs(toSend).^2); npow = 0.5 * spow ./ 10^(ebno / 10); attn = sqrt(npow); %% channel noise = attn.*(randn(1,Frame_len) + randn(1,Frame_len).*1i); data_noise = toSend + noise; extra_noise = attn.*(randn(1,50000) + randn(1,50000).*1i); end_noise = attn.*(randn(1,100000) + randn(1,100000).*1i); rx_signal = [extra_noise data_noise end_noise]; nn = (0:length(rx_signal)-1); rx_signal_fre_offset = rx_signal.*exp(1i*2*pi*cfo.*nn./fs); %% pre = CreatZC(500); ipoint = 20; irfn = 8; alfa = 0.5; % 由此可以得出带宽是10e3 * (1.5) = 15e3; recvFilter = rcosdesign(alfa, irfn, ipoint, 'sqrt'); freqComp = comm.CoarseFrequencyCompensator(... 'Modulation','QPSK', ... 'SampleRate',fs, ... 'FrequencyResolution',1);%粗频偏纠正 symbolSync = comm.SymbolSynchronizer('SamplesPerSymbol', ipoint);%符号同步器，纠正码元时延 fine = comm.CarrierSynchronizer( ... 'SamplesPerSymbol',1,'Modulation','QPSK');%纠正载波频偏 i=1; while(true) % [data,datavalid,overflow] = rxPluto(); out = xcorr(rx_signal_fre_offset,pre); out = out(length(rx_signal_fre_offset):end); % figure(1) % plot(abs(out)); pos = find(abs(out) > 100); [pos_max,loc] = max(abs(out(pos(1):pos(1)+20))); pos1 = loc+pos(1)-1+500*2; data = rx_signal_fre_offset(pos1:20*totaldata+pos1-1 ); %data = agc(data); [rxData1, estFreqOffset] = freqComp(data'); % estFreqOffset; % % scatterplot(rxData1); % title('粗频偏纠正'); % 匹配滤波 rxData2 = conv(rxData1, recvFilter, 'same'); rxData3 = symbolSync(rxData2); if(length(rxData3) < totaldata) rxData3 = [rxData3', zeros(1, totaldata- length(rxData3))]'; else rxData3 = rxData3(1:totaldata); end % scatterplot(rxData3); % title('符号同步'); rxData4 = fine(rxData3);%相偏修正 % scatterplot(rxData4); % title('相偏纠正'); % 本来是取前100个训练符号来做纠正相偏，但是经过实际测试，发现前面一些点会因为没有收敛导致相位错误， % 所以直接取后50个来纠正 pre100 = rxData4(1: 100); pre100=pre100(51:end); pre100=pre100.'; a=repmat(-1+1j,1,50); anout = angle(pre100./a); anout = mean(anout); % scatterplot(a); rxData4 = rxData4./exp(1j*anout); rxData4=rxData4(101:end); % scatterplot(rxData4); % rxData4=rxData4.*exp(1j*pi/2); demodData = pskdemod(rxData4, 4, pi/4); % 解交织， 这里有一个符号映射bit的问题 bitDemap = QPSKDeMap(demodData); nCode = 1; %一个字节用8个bit编码 bitData_descramble = matdeintrlv(bitDemap, 10* nCode, nBytes / 10); % 比较误码率 % [~, rate] = biterr(demodData, symData'); [~, rate] = biterr(bitData, bitData_descramble); rate; rate1(i)=rate; i=i+1; if(rate<0.4) break end end % str = num2str(bitData_descramble); % str1=strrep(str,' ',''); % b=reshape(str1,8,x1*x2); % c=bin2dec(b'); % d=reshape(c,x1,x2); % imshow(uint8(d)); figure(1) scatter(real(rxData1),imag(rxData1)); title('粗频偏纠正'); figure(2) scatter(real(rxData3),imag(rxData3)); title('符号同步的波形'); figure(3) scatter(real(rxData4),imag(rxData4)); title('相偏纠正后的波形'); symerr(b,bitData_descramble)/length(b)