pulse shaper

Let's first implement this as a phase shifter. We take a range in the spectrum and offset the phase inside a window. This seems to be a bad idea as it generates signal everywhere, and we can't control the time offset arbitrarily.

Now let's assume we can twist the signal only on a fixed region of the spectrum

Now let's assume we split the spectrum with a gaussian selection. The selected region gets twisted while the rest is kept as is. The signal is formed back.