What would save radio is a forth band... Local, free and works!
Someday, FM will be the AM to a new band, and the new band will be cramped too.
Isn't Pulse Modulation basically the same thing as FM? Can't we utilize that?
(Here I go sounding like a complete imbecile again, right?)
FM and AM are modulation schemes. They are not "bands." Without a clear understanding of the difference between a modulation scheme and the frequency band in which it operates, your question makes no sense.
In North America, AM transmission (and the proprietary "HD Radio" digital transmission scheme) is used in the medium-wave band (540-1700 kHz), while FM transmission (and now the proprietary digital "HD Radio" transmission as well) is used in the VHF band, 88-108 MHz.
In Europe, Africa and parts of Asia, AM transmission (and the DRM digital transmission scheme) is also used in the long-wave band. By international treaty, that band is not used for broadcast in the Americas.
It is extraordinarily unlikely that any new frequency band or modulation scheme will be opened for broadcasting in North America in the foreseeable future. This is partially a result of the massive base of existing AM/FM receivers that would be unable to receive a new broadcast band (making it a huge economic challenge to any broadcaster hoping to find an audience there), and partially a result of regulatory policy that mandates spectrum auctions.
Many solid-state AM transmitters (Nautel's AMPFET series, for instance) are based on pulse-width modulation designs.