Numbers stations are shortwave stations ... send the audio – ideally a powerful shortwave transmitter, but for an intelligence agency on a budget, online streaming will work.

This is KDDI Corp.’s Yamata Transmitting Station, the nation’s only facility broadcasting shortwave radio programs ... who served as a guide when the station was shown to media representatives ...

Radio transmission in the 1.7-30 MHz frequency range worldwide. Like AM radio, shortwave signals reflect back from the ionosphere and follow the curvature of the earth. As a result, shortwave (SW ...