AM radio is a pretty poor standard considering how much power and bandwidth it uses, due much to the very limited modulation technology available in the 1920s.
DRM (no not that DRM--Digital Radio Mondiale) is a modern digital standard that promises much better spectral efficiency, power efficiency and range. See https://www.drm.org/. It is similar in concept to DAB, using an OFDM carrier, but with more robust error correction and equalisation, and lower bit rate codec to handle larger broadcast areas.
There is a hope that this could upgrade existing AM broadcast infrastructure, allowing rapid coverage of large areas without the expense of building out new towers.
The MW/HF bands are great for coverage because of the longer wavelength, relative to the VHF bands used for FM and DAB.
DRM (no not that DRM--Digital Radio Mondiale) is a modern digital standard that promises much better spectral efficiency, power efficiency and range. See https://www.drm.org/. It is similar in concept to DAB, using an OFDM carrier, but with more robust error correction and equalisation, and lower bit rate codec to handle larger broadcast areas.
There is a hope that this could upgrade existing AM broadcast infrastructure, allowing rapid coverage of large areas without the expense of building out new towers.
The MW/HF bands are great for coverage because of the longer wavelength, relative to the VHF bands used for FM and DAB.