带通采样以及ASKmatlab程序.doc

3软件无线电 指导教师：杨强 报告人：张畅附录(1)、SDR低通采样理论%parametersfs = 5e4;%采样频率注意fs至少是f的2倍或2倍以上f = 5e3;%信号的频率N = 1024;n = 1:1024; t= n/fs;deta_t = 1/fs;%采样间隔 %signalssn = sin(2*pi*f*t);%时域采样后的信号w = hanning(N);%加汉宁窗sn1 = sn.*w;%加窗减少频率泄露Sn_fft = fft(sn1);%频域信号Sn = abs(Sn_fft); %figuresfigure(1);plot(t,sn);title(s(n)的时域波形);grid on;xlabel(t);xlim(0 0.021);ylabel(幅度);figure(2);xax = -N/2:N/2-1/N*fs/1000;%将f轴单位变为kHzplot(xax,20*log10(fftshift(Sn);title(s(n)的频域波形);grid on;xlabel(f(kHz);ylabel(幅度(dB);ylim(-200 100);(2)、SDR带通采样理论%parametersf = 1.3e3;%基频fo = 100e6;%载波频率N = 1024;n = 1:1024;fs = 4e3;%采样频率t= 0:0.001:2;st = cos(2*pi*(f+fo)*n/fs);%带通抽样信号St1 = fft(st);St = abs(St1); st0 = cos(2*pi*(f+fo)*t);St0 = fft(st0);St2 = abs(St0); figure(1);plot(n,st);title(带通抽样信号时域图像);xlabel(n);xlim(0 1026);ylabel(幅度);grid on; figure(2);plot(t,st0);title(带通原始信号时域图像);xlabel(t);ylabel(幅度);grid on; figure(3);xax =-N/2:N/2-1/N*fs/1000;plot(xax,20*log10(fftshift(St);title(带通信号抽样后频域图像);xlabel(f(kHz);ylabel(幅度(dB);grid on;(3)、频率调制信号%频率调制%parametersfs = 1e3;%抽样频率ts = 1/fs;%采样率N = 1024;n = 0:1:N-1;t = n/fs;kf = 100.1;A = 100;Aw = 10;fc = 10000;%载波频率fm = 10;%调制信号频率mf = kf*Aw/(2*pi*fm);%signalss1 = A*cos(2*pi*fc*t).*cos(mf*sin(2*pi*fm*t);s2 = A*sin(2*pi*fc*t).*sin(mf*sin(2*pi*fm*t);s = s1-s2;%频率调制信号S0 = fft(s);S1 = fftshift(S0);S_0 = abs(S1);%figuresfigure(1);plot(t,s);title(频率调制信号时域图像);xlim(0,0.5);xlabel(t(s);ylabel(幅度);grid on;figure(2);xax = -N/2:N/2-1/N*fs/1000;plot(xax,20*log10(S_0);title(频率调制信号频域图像);xlabel(f(kHz);ylabel(幅度(dB);grid on;(4)、幅度调制信号、DSB信号、USB信号%parametersclear all;clc;close all;fs = 1e3;%抽样频率ts = 1/fs;%采样间隔N = 10000;n = 1:N;t = n/fs;ma = 0.5;fc = 200;%载波频率x = cos(2*pi*fc*t);%生成载波fm = 1;%调制信号频率m = cos(2*pi*fm*t);%基带信号%signalss = (1+ma*m).*x;%幅度调制信号s1= m.*x;%双边带信号DSBs2 = cos(2*pi*(fc+fm)*t);%SSB信号中的USBS1 = fft(s);S_1 = abs(S1);S2 = fft(s1);S_2 = abs(S2);S3 = fft(s2);S_3 = abs(S3);%figuresfigure(1);plot(t,s);title(幅度调制信号时域图像);xlim(0 1.5);xlabel(t(s);ylabel(幅度);grid on;figure(2);xax = -N/2:N/2-1/N*fs/1000;plot(xax,20*log10(fftshift(S_1);title(幅度调制信号频域图像);xlim(0.19 0.21);xlabel(f(kHz);ylabel(幅度(dB);grid on;figure(3);plot(t,s1);title(双边带调制信号时域图像);xlim(0 1.5);xlabel(t(s);ylabel(幅度);grid on;figure(4);xax1 = -N/2:N/2-1/N*fs/1000;plot(xax1,20*log10(fftshift(S_2);title(双边带调制信号频域图像);xlim(0.19 0.21);xlabel(f(kHz);ylabel(幅度(dB);grid on;figure(5);plot(t,s2);title(USB调制信号时域图像);xlim(0 1.0);xlabel(t(s);ylabel(幅度);grid on;figure(6);xax1 = -N/2:N/2-1/N*fs/1000;plot(xax1,20*log10(fftshift(S_3);title(USB调制信号频域图像);xlim(0.19 0.21);xlabel(f(kHz);ylabel(幅度(dB);grid on;(5)、2ASK信号%2ASK信号的时域和频域分析clear all;clc;close all;%清除一切。m = 1 1 1 0 0 0 1 0 1 1 0 1;%数字信号的序列（自己随便产生的）Lm = length(m);%序列的长度F = 200;%数字信号的带宽(1或0的带宽是200Hz)f = 800;%正弦载波信号的频率A = 1;%载波的幅度Q = f/F;%频率比，即一个码元宽度中的正弦周期个数M = 500;%一个正弦周期内的采样点数t = (0:M-1)/M/f;%一个正弦信号周期内的时间%signalscarry1 = repmat(A*sin(2*pi*f*t),1,Q);%一个码元宽度内的正弦载波信号Lcarry1 = length(carry1);%一个码元宽度内的信号长度carry2 = kron(ones(size(m),carry1);%载波信号ask = kron(m,carry1);%调制后的ASK信号N = length(ask);%ASK信号的长度tau = (0:N-1)/(M-1)/f;%时间Tmin = min(tau);%最小时间Tmax = max(tau);%最大时间T = ones(size(carry1);%一个数字信号1dsig = kron(m,T);Ask = fft(ask);Ask0 = abs(Ask);%imagesfigure(1);plot(tau,dsig);grid on;axis(Tmin Tmax -0.2 1.2);title(数字信号序列的图像);figure(2);plot(tau,carry2);xlim(0 0.06);grid on;title(载波时域图像);figure(3);plot(tau,ask);grid on;axis(Tmin Tmax -1.2*A 1.2*A);title(2ASK信号的时域图像);figure(4);xax = -N/2:N/2-1/N*Lm*F;plot(xax,20*log10(fftshift(Ask0);xlim(-300 300);title(2ASK信号的频域图像);grid on;(6)、16路信道化发射机%parametersclc;close all;clear all;a = 1;%幅度fs = 50;%内插前采样频率k = 1:16;%16路信号I = 16;%内插系数N = 1024;fk = 1:1:N;sk = zeros(16,N);%创建16行N列的零矩阵用来存放16路时域信号Sk = zeros(16,N);%创建16行N列的零矩阵用来存放16路频域信号for k = 1:16 sk(k,:) = a*(1+0.5*exp(j*2*pi*k*fk/fs);%输入16路时域信号endfor k = 1:16 Sk(k,:) = fft(sk(k,:);%16路信号频域endfigure(1);xax = -N/2:N/2-1/N*fs;plot(xax,20*log10(abs(fftshift(Sk(:,1:N);title(16原始复信号时域叠加图);xlabel(f(Hz);xlim(-5 25);ylabel(幅度);figure(2);h0 = fir1(265,0.5);HW = fft(h0,N);xax1 = -N/2:N/2-1/N*fs;plot(xax1,10*log10(abs(fftshift(HW);title(滤波器响应);xlabel(f(Hz);ylabel(幅度);%I倍内插，即16倍内插，此时fs变大N_1 = N*16;st = zeros(16,N_1);St = zeros(16,N_1);for k = 1:16 for g = 0:N-1 st(k,g*I+k) = sk(k,g+1); endendsum = zeros(1,N_1);for k = 1:16 sum = sum+st(k,1:N_1);endfor k = 1:16 St(k,:) = fft(sum(1,1:N_1);endfor k = 1:16 St(k,1:N) = St(k,1:N).*HW;endfigure(3);x