clear all;  close all;
syms A B t T positive; syms f real;
A = 1e-3; T = 2e-3;
m = [1 -1 1 1];
ff = linspace(2000,-2000,10000);
set(plot(ff,subs(FTofManyShiftedRect(A,f,T,m),f,ff),'k'),'LineWidth',1.5)
grid on; xlabel('f [kHz]')