2FSKreceive.rar_2FSK_GJU_NHQP_同步 解调

clc; clear all; close all; %--------------------接收--------------------% fs = 8000; f1 = 1000; f2 = 2000; disp('Sampling.'); yin= audiorecorder(fs,8,1,1); recordblocking(yin,4); y = (getaudiodata(yin))'; disp('Sample done.'); figure(1); plot(y); ylim([ -0.4 0.4]); title('输入波形'); %--------------------放大--------------------% % y=2.*y; %--------------------解调--------------------% t1 = 1/fs:1/fs:length(y)/fs; %第一路f1相干解调 s1 = cos(2*pi*f1*t1); yb1 = bandpass(y,f1); ym1 = yb1 .* s1; yL1 = lowpass(ym1,200); %第二路f2相干解调 s2 = cos(2*pi*f2*t1); yb2 = bandpass(y,f2); ym2 = yb2 .* s2; yL2 = lowpass(ym2,200); %经过带通滤波器后的波形显示 figure(2); subplot(2,1,1); plot(yb1); title('1000Hz带通滤波后波形'); ylim([-0.3,0.3]); subplot(2,1,2); plot(yb2); title('2000Hz带通滤波后波形'); ylim([-0.3,0.3]); %经过相干解调后的频谱 figure(3); Nfft = 4096; n = 0:Nfft-1; f = n*fs/Nfft; subplot(3,1,1),plot(f,abs(fft(y,Nfft))); title('输入调制信号频谱'); xlim([0 5000]); subplot(3,1,2),plot(f,abs(fft(yb1,Nfft))); title('1000Hz带通滤波后频谱'); xlim([0 5000]); subplot(3,1,3),plot(f,abs(fft(yb2,Nfft))); title('2000Hz带通滤波后频谱'); xlim([0 5000]); %经过乘法滤波器后的波形显示 figure(4); subplot(2,1,1),plot(ym1); title('经过乘法器后波形.第一路'); ylim([-0.3,0.3]); subplot(2,1,2),plot(ym2); title('经过乘法器后波形.第二路'); ylim([-0.3,0.3]); %经过低通滤波后波形 figure(5); subplot(2,1,1),plot(yL1); title('200Hz低通滤波后波形.第一路'); ylim([-0.3,0.3]); subplot(2,1,2),plot(yL2); title('200Hz低通滤波后波形.第二路'); ylim([-0.3,0.3]); %抽样判决 n = length(yL1); m = length(yL2); p = max(m,n); %max还是min yd = zeros(1,p); % y1max = max(abs(yL1)); for i=1:p if abs(yL2(i)) >= abs(yL1(i)) yd(i) = 1; else yd(i) = 0; end end % for i=1:p % if abs(yL1(i)) > 0.2*y1max % yd(i) = 0; % else yd(i) = 1; % end % end figure(6); plot(yd); title('抽样判决结果'); ylim([-0.5,1.5]); %--------------------同步--------------------% q = length(yd); r =1; ys1 = [1 0 1 0 1 0 1 0 1 0 ]; a = 100; for j =1:q ys2(1) = round(sum(yd(j:j+99))/a); ys2(2) = round(sum(yd(j+100:j+199))/a); ys2(3) = round(sum(yd(j+200:j+299))/a); ys2(4) = round(sum(yd(j+300:j+399))/a); ys2(5) = round(sum(yd(j+400:j+499))/a); ys2(6) = round(sum(yd(j+500:j+599))/a); ys2(7) = round(sum(yd(j+600:j+699))/a); ys2(8) = round(sum(yd(j+700:j+799))/a); ys2(9) = round(sum(yd(j+800:j+899))/a); ys2(10) = round(sum(yd(j+900:j+999))/a); % ys2(11) = round(sum(yd(j+1000:j+1099))/a); % ys2(12) = round(sum(yd(j+1100:j+1199))/a); % ys2(13) = round(sum(yd(j+1200:j+1299))/a); % ys2(14) = round(sum(yd(j+1300:j+1399))/a); if ys2 == ys1 r = j; break; end end % yd2 = yd(r+700:r+700+12600-1); yd2 = yd(r+1400:r+1400+12600-1); for k = 1:126 yd3 = yd2(100*(k-1)+1:100*k); yi(k) =round(sum(yd3)/100); if yi(k) > 0.6 yi(k) = 1; else yi(k) = 0; end end figure(7); stem(yi); title('输入调制信号经过码形同步后得到的信息码'); ylim([-0.1,1.1]); %--------------------译码--------------------% H=[1 1 1 0 1 0 0 ;1 1 0 1 0 1 0;1 0 1 1 0 0 1]; ya = reshape(yi,7,18); yb = ya'; S=mod(yb*H',2); yout = zeros(1,18); % Ssum = sum(S); if S == 0 e = 0; else e = 1; for i=1:18 h=0; for j=1:3 h = h+S(i,j)*(2.^(3-j));%将二进制转换为十进制 end if h ~= 0 switch h case 1 yb(i,7)=~yb(i,7); case 2 yb(i,6)=~yb(i,6); case 3 yb(i,4)= ~yb(i,4); case 4 yb(i,5)=~yb(i,5); case 5 yb(i,3)=~yb(i,3); case 6 yb(i,2)=~yb(i,2); case 7 yb(i,1)=~yb(i,1); end else yb(i,:)=yb(i,:); end end end yc = yb(:,1:4); for i= 1:18 u = 0; for j=1:4 u = u +yc(i,j)*(2.^(4-j));%将二进制转换为十进制 end yout(i) = u; end % yout = gray(yc); disp(yout);