function [y,iflaw]=dopnoise(N,Fs,f0,d,v,t0,c);%DOPNOISE Complex noisy doppler signal.%	[Y,IFLAW]=DOPNOISE(N,FS,F0,D,V,T0,C) generates a complex %	noisy doppler signal, normalized so as to be of unit energy. %%	 N  : number of points.  %	 FS : sampling frequency (in Hertz).  %	 F0 : target frequency   (in Hertz).  %	 D  : distance from the line to the observer (in meters).  %	 V  : target velocity    (in m/s).  %	 T0 : time center                  (default : N/2).  %	 C  : wave velocity      (in m/s)  (default : 340).%	 Y  : Output signal.%	 IFLAW : Model used as instantaneous frequency law.%%	Example :%	 [z,iflaw]=dopnoise(500,200,60,10,70,128);%	 subplot(211); plot(real(z)); %	 subplot(212); plot(iflaw); hold; ifl=instfreq(z,11:478,10);%	 plot(ifl,'g'); hold; sum(abs(z).^2)%	 axis([0 468 -0.01 0.51])%	F. Auger, July 94, August 95.%	Copyright (c) 1996 by CNRS (France).%%	------------------- CONFIDENTIAL PROGRAM -------------------- %	This program can not be used without the authorization of its%	author(s). For any comment or bug report, please send e-mail to %	f.auger@ieee.org if (nargin <= 4), error ( 'At least 5 parameters are required' ); elseif (nargin == 5), t0=N/2; c=340.0;elseif (nargin == 6), c=340.0;end;if (N <= 0), error ('The signal length N must be strictly positive' );elseif (Fs<0), error ('The sampling frequency FS must be positive');elseif (t0<1)|(t0>N), error ('T0 must be between 1 and N');elseif (f0<0)|(f0>Fs/2), error ('F0 must be between 0 and FS/2');elseif (v<0), error ('V must be positive');else r=0.9; rr=r*r; r2=r*2; vv=v*v; x=randn(2*N,1); tmt0=((1:2*N)'-t0-N)/Fs ; dist=sqrt(d^2+(v*tmt0).^2); iflaw=(1-vv*tmt0./dist/c)*f0/Fs;  y=zeros(2*N-2,1); for t=3:2*N,  y(t)=x(t)-rr*(x(t-2)+y(t-2))+r2*cos(2.0*pi*iflaw(t))*y(t-1); end;  y=hilbert(y(N+1:2*N) ./ sqrt(dist(N+1:2*N)));  y=y/sqrt(sum(abs(y).^2)); iflaw=iflaw(N+1:2*N);end;