bppmsource.m

该程序仿真超宽带的脉冲位置调制。是在MATLAB下实现的。

function [sys,x0,str,ts] = BPPMsource(t,x,u,flag,T)

switch flag,

  %%%%%%%%%%%%%%%%%%
  % Initialization %
  %%%%%%%%%%%%%%%%%%
  case 0,
    sizes = simsizes;

    sizes.NumContStates  = 0;
    sizes.NumDiscStates  = 1;
    sizes.NumOutputs     = 1;
    sizes.NumInputs      = 0;
    sizes.DirFeedthrough = 0;
    sizes.NumSampleTimes = 1;   % at least one sample time is needed

    sys = simsizes(sizes);
    
    x0  = [0];
    str = []; ts  = [0 0];

  %%%%%%%%%%%%%%%
  % Derivatives %
  %%%%%%%%%%%%%%%
  case 1,
    sys=[];

  %%%%%%%%%%
  % Update %
  %%%%%%%%%%
  case 2,
      if abs(round(t/T) - t/T) < 1e-8
          sys=rand(1)>0.5;
      end

  %%%%%%%%%%%
  % Outputs %
  %%%%%%%%%%%
  case 3,
      sys = x(1);

  %%%%%%%%%%%%%%%%%%%%%%%
  % GetTimeOfNextVarHit %
  %%%%%%%%%%%%%%%%%%%%%%%
  case 4,
    sys=[];
  %%%%%%%%%%%%%
  % Terminate %
  %%%%%%%%%%%%%
  case 9,
     sys=[];
     
  %%%%%%%%%%%%%%%%%%%%
  % Unexpected flags %
  %%%%%%%%%%%%%%%%%%%%
  otherwise
    error(['Unhandled flag = ',num2str(flag)]);

end