A few weeks before the COVID-19 pandemic shut down much of the world, broadcast engineers in Greenville, North Carolina, launched a test of digital radio signals. The U.S. Agency for Global Media began aiming a digital broadcast at Cuba and Latin America, which included Office of Cuba Broadcasting and Voice of America content.
With this 2020 test, VOA embarked on a new phase of global innovation on a platform called Digital Radio Mondiale (DRM), a versatile digital signal not well known in the U.S., but the only one that can cover the entire spectrum: shortwave, mediumwave and longwave, as well as VHF (FM). As digital radio emerged in the 1990s, VOA was among the first broadcasters testing a signal that promised to even out shortwave radio signals that often faded in and out and were marred by static.
VOA tested the DRM signal in the 1990s at the agency’s Morocco transmitter site, one of five facilities opened in a period of expansion in the previous decade. However, other digital signals became the standard in various markets around the world. The U.S. standard audio digital platform is called HD.
Around the world, as other digital radio platforms were adopted, DRM was held back by the marketplace. Nobody was making commercially available receivers.
By the end of the 1990s, VOA innovation focused more on television, the platform that promised larger audiences, even in some places in the world where shortwave dominated. By the early 2010s, the rallying cry became “Digital First,” as VOA strived to attract readers for its language service websites and began tapping into the growing audiences on new social media sites like Facebook, Twitter, Instagram and YouTube.
By 2020, however, DRM had come full circle.
“You’re no longer limited to just reading the news or playing music,” says Gerhard Straub, supervisory director of the USAGM Broadcast Technologies Division.
Edward R. Murrow Transmitting Station in Greenville, North Carolina
Straub, along with Gary Koster, Broadcast Radio Technician and transmitter expert and Macon Dail, Chief Engineer at the Greenville Transmitting Station, set up the test broadcast in February of this year, not long before the COVID-19 pandemic grounded global travel. The trio put up a DRM signal with Radio Marti and VOA audio along with scrolling text messages and rotating images.
Engineers have received reports of a clear signal as far south as Brazil.
The USAGM test, says Straub, is “coasting along” in the pandemic, but additional content will be added when technicians can travel again. Straub says the VOA signal was taken off in the initial test to concentrate on the OCB digital content and to keep the signal robust. Now that there is good reception data, he noted, the digital bit rate can be increased and VOA content added back into the test in 2021.
A DRM receiver tuned to the VOA test signal.
Because DRM operates at lower power, more radio stations and digital signals can be broadcast on a single transmitter. The platform is starting to grow in countries of interest to Western international broadcasters. DRM signals will soon cover all of China, though its government is expected to attempt to control the stations accessed by its citizens. India built 39 transmitters and, more importantly, 2.5 million vehicles already are equipped with DRM radios. Indonesia, Pakistan, Brazil and North Korea all have nascent DRM operations.
Religious broadcasters, who sometimes target audiences similar to those sought by Western governments, are experimenting with the technology. For example, a missionary group, TWR.org, sent the Bible’s Gospel of Mark from Guam to Cambodia via DRM shortwave.
“You have to stop thinking of it as radio, because it’s not,” says USAGM’s Straub. “We are now broadcasting digital data. Just like we broadcast digital data on the internet, we can broadcast digital data over shortwave without being hampered by an internet firewall that maybe limits what we can send to a particular country.”
Reason enough, Straub believes, for VOA to continue leading innovation in a new-again technology.