chap2_figs7_11&12.m

无线通讯系统的matlab仿真程序；主要包括同步

% Chap2_Figs7_11&12.m
clc, clear all, close all

hold on
max_x=1;
wn=1;
t=linspace(0,6*pi/wn,500);
for n=1:5
    x0=-1+2*rand;
    x0_dot=-1+2*rand; 
    x=x0*cos(wn*t)+(x0_dot/wn)*sin(wn*t);
    if max(x)>max_x
        max_x=max(x);
    end
    xdot=-wn*x0*sin(wn*t)+x0_dot*cos(wn*t);
    figure(1)
    plot(x,xdot)
    plot(x0,x0_dot,'.r','MarkerSize',10)
    axis equal
    M=1.1*max_x;
    axis([-M M -M M])
plot([-M M],[0 0],'k')
plot([0 0],[-M M],'k')
xlabel('\itx','FontSize',11)
ylabel('\itdx/dt','FontSize',11)
title('State Trajectories of Undamped Second Order Systems (Random Initial States)','FontSize',11)
  %if n==1|n==3|n==5
    figure(2)
    subplot(2,1,1)
    hold on
    plot(t,x)
    axis([0 t(end) 1.1*min(x) 1.1*max(x)])
    ylabel('\itx','FontSize',11)
    title('Sustained Oscillations of \itx \rmfor Undamped Second Order Systems','FontSize',11)
    subplot(2,1,2)
    hold on
    plot(t,xdot)
    axis([0 t(end) 1.1*min(xdot) 1.1*max(xdot)])
    xlabel('\itt','FontSize',11)
    ylabel('\itdx/dt','FontSize',11)
    title('Sustained Oscillations of \itdx/dt \rmfor Undamped Second Order Systems','FontSize',11)
    %end
end
figure(1)
gtext('\omega_{\itn} \rm= 1 rad/sec','FontSize',11)