function [y,pm0]=anaqpsk(N,Ncomp,f0);%ANAQPSK Quaternary Phase Shift Keying (QPSK) signal.% 	[Y,PM]=ANAQPSK(N,NCOMP,F0) returns a complex phase modulated signal% 	of normalized frequency F0, whose phase changes every NCOMP point according%	to a discrete uniform law, between the values (0, pi/2, pi, 3*pi/2).% 	Such signal is only 'quasi'-analytic.%	%	N     : number of points%	NCOMP : number of points of each component (default: N/5)% 	F0    : normalized frequency.              (default: 0.25)% 	Y     : signal% 	PM0   : initial phase of each component	   (optional).%%	Example :%	 [signal,pm0]=anaqpsk(512,64,0.05); clf; figure(gcf);%  	 subplot(211); plot(real(signal)); subplot(212); plot(pm0);%%	See also ANAFSK, ANABPSK, ANAASK.%	O. Lemoine - October 1995%	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 == 0), error('The number of parameters must be at least 1.');elseif (nargin == 1), Ncomp=round(N/5); f0=0.25;elseif (nargin == 2), f0=0.25;end;if (N <= 0), error('The signal length N must be strictly positive' );elseif (f0<0)|(f0>0.5), error('f0 must be between 0 and 0.5');end;MatlabVersion=version; MatlabVersion=str2num(MatlabVersion(1));if (MatlabVersion==4), rand('uniform'); end;m=ceil(N/Ncomp);% jumps=round(3*rand(m,1));% This is a modification proposed by Alpesh Patel, McMaster Universityjumps=floor(4*rand(m,1)); jumps(jumps==4)=3;pm0=pi*kron(jumps,ones(Ncomp,1))/2; pm0=pm0(1:N,1);tm=(1:N)'-1;pm=(2.0*pi*f0*tm+pm0);y = exp(j*pm);