【信号处理】数字双相码仿真含Matlab源码

close all clear all %采样点数的设置 k = 14; %每码元采样数的设置 L = 128; N = 2^k; M = N/L;%M为码元个数 dt = 1/L;%时域采样间隔 T = N*dt;%时域截断区间 df = 1.0/T;%频域采样间隔 Bs = N*df/2;%频域截断区间 t = linspace(-T/2,T/2,N);%产生时域采样点 f = linspace(-Bs,Bs,N);%产生频域采样点 EP1 = zeros(size(f)); EP2 = zeros(size(f)); EP3 = zeros(size(f)); for x=1:1000 % 取样1000次 K = round(rand(1,M)); %产生一个长度为M的随机序列K，0和1等概出现 original = zeros(L,M); %产生一个L行M列的original矩阵，初始化为全0矩阵 Manchester = zeros(L,M); %产生一个L行M列的Manchester矩阵，初始化为全0矩阵 for i=1:M if K(i)==1 original (:,i)=1;%原码 Manchester (1:L/2,i)=1; %使manchester矩阵第i列前L/2个元素为1 else original (:,i)=0;%原码 Manchester (:,i)=1; %使manchester矩阵第i列为1 Manchester (1:L/2,i)=0; %使manchester矩阵第i列前L/2个元素为0 end end %分别重排nrz、manchester矩阵为1行N列的矩阵 original = reshape(original,1,N); Manchester = reshape(Manchester,1,N); %做傅里叶变换并算出功率谱密度 ORIGINAL = t2f(original,dt); P1 = ORIGINAL.*conj(ORIGINAL)/T; MANCHESTER = t2f(Manchester,dt); P2 = MANCHESTER.*conj(MANCHESTER)/T; %求功率谱密度的均值 EP1 = (EP1*(x-1)+P1)/x; EP2 = (EP2*(x-1)+P2)/x; end figure(1) %开启一个编号为1的绘图窗口 subplot(2,2,1); plot(t,original); %画原码的时域图 axis([-3,3,min(original)-0.1,max(original)+0.1]); title(’原码’,’fontsize’,12); xlabel(’t(ms)’,’fontsize’,12); ylabel(’original(t)’,’fontsize’,12); grid on subplot(2,2,2); plot(t,Manchester) ; %画数字双相码的时域图 axis([-3,3,min(Manchester)-0.1,max(Manchester)+0.1]); title(’数字双向码’,’fontsize’,12); xlabel(’t(ms)’,’fontsize’,12); ylabel(’Manchester (t)’,’fontsize’,12); grid on subplot(2,2,3);plot(f,EP1); %画原码的功率谱密度图 axis([-5,5,0,0.3]); title(’原码功率谱密度图’,’fontsize’,12); xlabel(’f(kHz)’,’fontsize’,12); ylabel(’P1(f)’,’fontsize’,12); grid on subplot(2,2,4);plot(f,EP2) ; %画数字双相码的功率谱密度图 axis([-5,5,0,0.15]); title(’数字双相码功率谱密度图’,’fontsize’,12); xlabel(’f(kHz)’,’fontsize’,12); ylabel(’P2(f)’,’fontsize’,12); grid on