function   x = chirp( T, W, p )%CHIRP    generate a sampled chirp signal%-----       exp(j(W/T)pi*t^2)   -T/2 <= t < +T/2%%   Usage:   X = chirp( T, W, <P> )%%      X :  N=pTW samples of a "chirp" signal%      T :  time duration from -T/2 to +T/2%      W :  swept bandwidth from -W/2 to +W/2%%   optional (default is P = 1)%      P :  samples at P times the Nyquist rate (W)%            i.e., sampling interval is 1/(PW)%---------------------------------------------------------------% copyright 1994, by C.S. Burrus, J.H. McClellan, A.V. Oppenheim,% T.W. Parks, R.W. Schafer, & H.W. Schussler.  For use with the book% "Computer-Based Exercises for Signal Processing Using MATLAB"% (Prentice-Hall, 1994).%---------------------------------------------------------------if nargin < 3   p = 1;   end    J = sqrt(-1);%--------------delta_t = 1/(p*W);N = round( p*T*W );    %--- same as T/delta_tnn = [0:N-1]';x = exp( J*pi*W/T * (delta_t*nn - T/2).^2 );