"Telamon" wrote

Yes and that would be the case for NRZ data or
non return to zero data.
___________

Once past the pulse transition, NRZ "data" is nothing but a different value
of DC -- the bandwidth of which is infinitely small.

If NRZ data is amplitude modulated onto a carrier via a DC-coupled
modulator, then the effect is to change the amplitude of the carrier from
one steady-state value to another. The occupied spectrum is infinitely
small for steady-state carriers.

For frequency modulation, DC-coupled NRZ data will change the carrier from
one frequency to another, each of which will be infinitely small during
steady-state conditions.

RF