The Digital Radio Mondiale Consortium (DRM) says it’s pleased to learn that the Federal Communication Commission (FCC) of the USA has granted a licence to Digital Aurora Radio Technologies (DART) that will conduct a 2 year experiment for coverage of the state of Alaska with DRM signals in three of the lower shortwave bands around 5, 7 & 9 MHz.The Consortium says that if the tests show excellent results for digital broadcasts to cover the entire state, the next step would be to obtain approval to use the DRM system and the transmission station for a regular broadcasting service.
Alaska has a surface area of approximately 1,300,000 square kilometres. With one DRM transmission, either 10 or 20 kHz in bandwidth, the entire state would be covered with approximately “FM-like” quality for up to 4 simultaneous programmes, such as four different languages of newscasts.
Because of the severe ionospheric propagation conditions at the high latitudes for the state, these experiments will yield valuable information on what is needed to get excellent audio coverage at realistic powers for this concept – that is, for “regional coverage” on the order of hundreds of thousands to perhaps 2 million square kilometres from one shortwave transmitter located “in the middle” of the coverage area.
The full test plan will include several variations of DRM system variables in order to determine which combination works best under the different ionospheric propagation conditions to be encountered. For the latter, this includes sunspot number, season and time of day.
For the former, it involves different levels of audio quality for example with or without stereo and different levels of error correction. Finally, there is the choice of the 3 shortwave broadcasting bands at around 5, 7 & 9 MHz.
(Source: DRM Consortium/R Netherlands Media Network Weblog)