acquisition.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] = acquisition(t,x,u,flag,threshold,numPulse2Observe,falseAlarm,Np,tau,Ts,Ep)

global UWB_SIG_DETECT_ON;
global ACQUISITION_ON;
global NEXT_PULSE_TIME;
global NEXT_HOPPING_ON;
global INTEGRATION_START_TIME;
global DATA_ON;

switch flag,

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

    sizes.NumContStates  = 0;
    sizes.NumDiscStates  = 3;
    sizes.NumOutputs     = 0;
    sizes.NumInputs      = 2;
    sizes.DirFeedthrough = 0;
    sizes.NumSampleTimes = 1;   % at least one sample time is needed

    sys = simsizes(sizes);
    
    x0  = [0 0 0]; % subtotal, number of pulses observed, number of try
    str = []; ts  = [0 0];
    
    ACQUISITION_ON=0;

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

  %%%%%%%%%%
  % Update %
  %%%%%%%%%%
  case 2,
      integrationEndTime=NEXT_PULSE_TIME+floor(2*tau/Ts)*Ts;
      if abs(t/INTEGRATION_START_TIME-1) < 1e-8
          x(1)=0; x(2)=0;
      elseif abs(t/NEXT_PULSE_TIME-1) < 1e-8
          x(2)=x(2)+1;
      elseif x(2)==numPulse2Observe & abs(t/integrationEndTime-1) < 1e-8
          if ACQUISITION_ON==3
              ACQUISITION_ON=2;
              fprintf('Tracking Coeffient=%3.3f percent\n',x(1)/sqrt(Ep)/x(2)*100)
              if x(1)/sqrt(Ep)/x(2)*100 < falseAlarm
                  disp('FALSE ALARM!!. A new acquisition required...');
                  UWB_SIG_DETECT_ON=0; ACQUISITION_ON=0; DATA_ON=0;
              end
          elseif ACQUISITION_ON==0
              x(3)=x(3)+1;
              fprintf('Acquisition Coeffient=%3.3f percent\n',x(1)/sqrt(Ep)/x(2)*100)
              if x(1)/sqrt(Ep)/x(2)*100 > threshold
                  disp('PN Hopping Code acquired...!!');
                  ACQUISITION_ON=1;
              elseif x(3)==Np
                  UWB_SIG_DETECT_ON=0; x(2)=0;x(3)=0;
              else
                  NEXT_HOPPING_ON=1; x(2)=0;
              end
          end
      end
      x(1)=x(1)+u(1)*u(2)*Ts;
      sys=x;
      
  %%%%%%%%%%%
  % Outputs %
  %%%%%%%%%%%
  case 3,
      sys=[];
      
  %%%%%%%%%%%%%%%%%%%%%%%
  % GetTimeOfNextVarHit %
  %%%%%%%%%%%%%%%%%%%%%%%
  case 4,
      sys=[];

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

end