Matlab.rar_matlab频率噪声_解调 matlab滤波_频率解调_频率调制

function work_2 %%%%为了方便看波形 建一个窗口 实现点一下鼠标换个波形 handles.figure = figure ('unit','normalized','position',[0.07,0.07,0.85,0.85],... 'WindowButtonDownFcn',@Draw); %%%%%%% %%%%%% handles.flag = 1; handles.flagMax = 7; fc = 1000 ; %载波频率 fs = 10000; %采样频率 f0 = 100; %码元速率 N = 100; bits = [];sig = [];z = []; SNR = 10; t = 0 : 1/fs : 10*(1/fs)*100 - (1/fs); %%%%%%%%% %%%%%%%%%%%每个码元对应10个载波周期、每个载波周期采样10个点 %%%%%%%%%每个码元周期采样100个点 function Draw(t1,t2) flag = handles.flag; if(flag == 1) %数字信号 %%%%%%%%%% bit = [0 1 1 0 1 1 0 0 1 0]; %10个数字信号 for i = 1 : length(bit) if bit(i) == 0 bits = zeros(1,N); else bits = ones(1,N); end sig = [sig,bits]; end subplot(2,1,1);plot(sig); axis([0,1000,-0.5 ,1.5]); title('信号波形'); xlabel('t'); [Pxx,Pxxc,f] = pmtm(sig,3.5,1024,fs,0.99); hpsd = dspdata.psd(Pxx,'Fs',fs); subplot(2,1,2);plot(hpsd); title('信号波形频谱'); xlabel('t'); %%%%%%%%%%%%%%%%%%% end; if(flag == 2) %调制信号 %%%%%%%%%%%%%%% c = cos(2*pi*fc*t); z = [z,c]; handles.y0 = z.*sig; subplot(2,1,1);plot(t,handles.y0); axis([0 100*(1/fc) -1.5 1.5]); title('调制信号波形'); xlabel('t'); [Pxx,Pxxc,f] = pmtm(handles.y0,3.5,1024,fs,0.99); hpsd = dspdata.psd(Pxx,'Fs',fs); subplot(2,1,2);plot(hpsd); title('调制信号波形频谱'); xlabel('t'); %%%%%%%%%%%%%%%%%%% end; if(flag == 3) %添加噪声 %%%%%%%%%%%%%%%% handles.y1 = awgn(handles.y0,SNR,'measured'); subplot(2,1,1);plot(t,handles.y1); axis([0 100*(1/fc) -1.5 1.5]); title('加噪声后的调制信号波形'); xlabel('t'); [Pxx,Pxxc,f] = pmtm(handles.y1,3.5,1024,fs,0.99); hpsd = dspdata.psd(Pxx,'Fs',fs); subplot(2,1,2);plot(hpsd); title('加噪声后调制信号波形频谱'); xlabel('t'); %%%%%%%%%%% end; if(flag == 4) %带通滤波 Wp = [800 1200]/(fs/2); Rp = 0.1; Rs = 10; [b,a] = ellip(4,Rp,Rs,Wp); handles.y2 = filter(b,a,handles.y1); subplot(2,1,1);plot(t,handles.y2); axis([0 100*(1/fc) -1.5 1.5]); title('带通滤波后的调制信号波形'); xlabel('t'); [Pxx,Pxxc,f] = pmtm(handles.y2,3.5,1024,fs,0.99); hpsd = dspdata.psd(Pxx,'Fs',fs); subplot(2,1,2);plot(hpsd); title('带通滤波后的调制信号波形频谱'); xlabel('t'); %%%%% end; if(flag == 5) %解调 %%%%%%%% handles.y3 = handles.y2 .*cos(2*pi*fc*t); subplot(2,1,1);plot(t,handles.y3); axis([0 100*(1/fc) -1.5 1.5]); title('解调后的信号波形'); xlabel('t'); [Pxx,Pxxc,f] = pmtm(handles.y3,3.5,1024,fs,0.99); hpsd = dspdata.psd(Pxx,'Fs',fs); subplot(2,1,2);plot(hpsd); title('解调后的信号波形频谱'); xlabel('t'); %%%%%%%%% end; if(flag == 6) %低通滤波 Wp = 950/(fs/2); Rp = 0.1; Rs = 10; [b,a] = ellip(4,Rp,Rs,Wp); handles.y4 = filter(b,a,handles.y3); subplot(2,1,1);plot(t,handles.y4); axis([0 100*(1/fc) -1.5 1.5]); title('低通滤波后的解调信号波形'); xlabel('t'); [Pxx,Pxxc,f] = pmtm(handles.y4,3.5,1024,fs,0.99); hpsd = dspdata.psd(Pxx,'Fs',fs); subplot(2,1,2);plot(hpsd); title('低通滤波后的解调信号波形频谱'); xlabel('t'); %%%%% end; if(flag == 7) %抽样判决、硬判决 %%%%%%%%%%%% BITS = [];SIG = [];Z = []; t = f0/2; % for i = 1 : 10 %%%%%判决电平 if(handles.y4(t) > 0.5) Z(i) = 1; %%%%%取0.5为判决电平 else Z(i) = 0; end t = t + f0; end for i = 1 : length(Z) if Z(i) == 0 BITS = zeros(1,N); else BITS = ones(1,N); end SIG = [SIG,BITS]; end subplot(2,1,1);plot(SIG); axis([0,1000,-0.5 ,1.5]); title('硬判决后的信号波形'); xlabel('t'); [Pxx,Pxxc,f] = pmtm(SIG,3.5,1024,fs,0.99); hpsd = dspdata.psd(Pxx,'Fs',fs); subplot(2,1,2);plot(hpsd); title('硬判决后的信号波形频谱'); xlabel('t'); %%%%%%%%%% end; if(handles.flag < handles.flagMax) handles.flag = handles.flag + 1; end ; end end