prbs_a - pseudo random binary sequences generation
generation of pseudo random binary sequences u=[u0,u1,...,u_(n-1)]; u takes values in {-1,1} and changes at most nc times its sign. ids can be used to fix the date at which u must change its sign ids is then an integer vector with values in [1:n] .
u=prbs_a(50,10);
plot2d2("onn",(1:50)',u',1,"151",' ',[0,-1.5,50,1.5]);