Digital Radio Mondiale (DRM) is a flexible open-source standards-based protocol for digital broadcasting both inside and outside of the broadcast bands. DRM30 is used on the longwave (LW), medium wave (AM broadcast band) and high frequency (HF) (shortwave) spectrum. DRM+ (DRM Plus) is a version of the protocol that is used on VHF bands including the FM broadcast band as well as any dedicated spectrum that a nation may allocate to digital broadcasting.
Currently, DRM30 is starting to be implemented in India in both a "pure-DRM" form as well as hybrid with analog AM (utilizing two adjacent 9 kHz AM channels). In addition, some international broadcasters including Radio France International, BBC World Service, Radio Romania, China National Radio and Radio New Zealand International have regularly scheduled DRM broadcasts on shortwave. None of these broadcasts are currently targeted to North America.
For licensed international broadcasters in the USA, the FCC has recognized and accepts DRM as a standard for broadcasting in the HF spectrum. No US shortwave broadcaster has yet to implement a regular schedule of DRM. The FCC has recently granted a construction permit for a new 10 kW international broadcast station running DRM to be placed adjacent to the Armstrong Alpine Tower in New Jersey. Once on the air, this station will beam programming to Europe using exclusively DRM. DRM is not permitted in the USA for the AM or FM broadcast bands as the FCC has determined that HD Radio would be the standard.
In the LW, AM and HF bands, DRM can operate different modes ranging in bandwidth from 4.5 to 20 kHz wide. A DRM transmission can support up to four services including voice and datacasting services. The sound quality of the streams depend on how many different services operate from the same transmission. Using DRM on HF, shortwave broadcasters can transmit high quality mono or parametric stereo sound.
In the VHF bands, DRM can provide up to a 100 kHz wide digital audio channel which can deliver CD quality sound, multiple streams and datacasting, all in a package that takes up less spectrum than analog FM or hybrid HD Radio.
With compatible radio receivers, DRM can provide datacasting which can including sending still images to semi-interactive news and information services.
The nice thing about DRM is that the station's streams exist as button selections and will display with all other services the radio can receive. There's no need for listeners to remember a frequency. In addition, DRM does not require as much power as a standard analog AM or shortwave signal. The studies have shown that a 10 kW shortwave transmitter running DRM is about the equivalent of a 50 kW+ double sideband AM analog transmitter this meaning less power consumption and potentially a "greener" form of radio.
Currently, there is not a good selection of available DRM receviers. There are a small number of portable sets (including those still in prototype) as well as software that can be ran with software defined radio (SDR) hardware to receive the broadcasts. This will improve as DRM grows and especially if there is ever a DRM-based service in the USA, this can definitely get the receiver industry taking off more. The industry is working towards DRM radio receivers for the AM and HF bands that will be under the $50 price point. Companies like Nautel and Continental Electronics are currently building DRM capable high-powered shortwave and AM transmitters.
REC supports the DRM movement as we feel that a DRM deployment on underused spectrum could bring new community radio services into metropolitan areas where LPFM is not available due to spectrum crowding and reach out to immigrant and religious communities in these areas who are not currently being served by traditional AM and FM radio and in a way where a wireless broadband or internet service subscription is not required.
REC is currently building relationships with those in the industry and those who support the proliferation of DRM and is currently compling the technical aspects of the service to develop a regulatory strategy that could result in a narrowcast type of radio service to serve communities currently excluded from current and future LPFM growth.
REC is interested in hearing from non-profit organizations, especially those in New York City, Boston, South Florida, Chicago, Los Angeles and San Francisco who work with minority language and religious communities that are trying to reach out to the community, especially those who do not subscribe to internet services. Your efforts to put a good word into extended community radio will help us in the regulatory efforts to introduce this type of service across America!
We will have more information at a later time. For now, if you want to read more about DRM, please check out the DRM Consortium official website.
