the article says they are originating in NK...
continuous transmission by numbers stations are likely following the old Soviet example of continuous transmission along the fire chain of missile bases, that way you never know when they are going on alert like you would if everything was always quiet then all of a sudden message traffic starts up and down the fire chain telling you something is up
the article says they are originating in NK... Not exactly. It says the transmission was on a frequencey normally used by the NORKs. That doesn't necessarily mean the transmission originated in N. Korea. (Shortwave transmitters commonly step on each others' frequencies when they are hostile to one another.) I do not believe a single, amatuer HAM/shortwave receiver could determine the originating location.