Digital radio signals

[Opcom]

Most beacons in this range have left the airwaves, but some are still on, by my observations.

http://www.dxinfocentre.com/ndb.htm

These SW BC 'digital' stations show up on the same web page as the beacons.

http://dxinfocentre.com/hepburn/vox_dx_sw.html

Are these the "Digital Radio Mondiale" format? Is that the only format used for digital SW BC stuff? And, is a decoder an option to hang off an I.F. of a radio?