chap2_figs7_11and12.m

无线通讯系统的matlab仿真程序；主要包括同步

% Chap2_Figs7_11and12.m
clc, clear all, close all 
wn=1;
t=linspace(0,6*pi/wn,1000);

x0(1)=0.1; x0_dot(1)=0.1;
x0(2)=-0.3; x0_dot(2)=0.25;
x0(3)=-0.4; x0_dot(3)=-0.5;
x0(4)=0.85; x0_dot(4)=-0.2;
 
for i=1:4
   figure(1)
   hold on
   x=x0(i)*cos(wn*t)+(x0_dot(i)/wn)*sin(wn*t);
   xdot=-wn*x0(i)*sin(wn*t)+x0_dot(i)*cos(wn*t);  
   
    switch i
    case 1        
         plot(x,xdot,'b')
         plot(x0(i),x0_dot(i),'.b','MarkerSize',12)
     case 2 
         plot(x,xdot,'r')
         plot(x0(i),x0_dot(i),'.r','MarkerSize',12)
    case 3
         plot(x,xdot,'g')
         plot(x0(i),x0_dot(i),'.g','MarkerSize',12)         
    case 4
         plot(x,xdot,'k')
         plot(x0(i),x0_dot(i),'.k','MarkerSize',12)
    end  
      
   axis equal
   axis([-1.1 1.1 -1.1 1.1])
  
  figure(2)
  subplot(2,1,1)
  hold on
  
  switch i
    case 1
        plot(t,x,'b')
        text(0.22,0.26,'a')
    case 2 
        plot(t,x,'r')
        text(2.35,0.52,'b')
    case 3
        plot(t,x,'g')
        text(3.9,0.78,'c')
    case 4
        plot(t,x,'k')
        text(5.9,1,'d')
  end       
  
  axis([0 12 -1 1.1])
  ylabel('\itx','FontSize',11)
  title('Sustained Oscillations of \itx \rmfor Undamped Second Order Systems','FontSize',11)
  
  subplot(2,1,2)
  hold on
  
  switch i
    case 1
        plot(t,xdot,'b')
        text(1.5,-0.25,'a')
    case 2 
        plot(t,xdot,'r')
        text(3.9,-0.55,'b')
    case 3
        plot(t,xdot,'g')
        text(5.5,-0.77,'c')
    case 4
        plot(t,xdot,'k')
        text(7.5,-1.04,'d')
  end      
    
  axis([0 12 -1.15 1])
  xlabel('\itt','FontSize',11)
  ylabel('d\itx\rm/dt','FontSize',11)
  title('Sustained Oscillations of d\itx\rm/dt \rmfor Undamped Second Order Systems','FontSize',11)   
end

figure(1)
plot([-1 1],[0 0],'k')
plot([0 0],[-1 1],'k')
xlabel('\itx','FontSize',11)
ylabel('d\itx\rm/dt','FontSize',11)
title('State Trajectories of Undamped Second Order Systems','FontSize',11)  
text(0.25,1.0,'\omega_{\itn} \rm= 1 rad/sec','FontSize',11)
text(0.15,-1,'Initial State: \itx\rm(0), \itx\rm(0)','FontSize',11)
plot([0.1],[-1],'.k','MarkerSize',12)
text(0.887,-0.91,'.','FontSize',15)
text(0.13,0.125,'a') 
text(-0.36,0.31,'b') 
text(-0.45,-0.55,'c') 
text(0.89,-0.20,'d')