North Korea has returned to digital radio broadcasting after an absence of nearly two years.
The latest Digital Radio Mondiale (DRM) shortwave transmissions began mid August. The country has had periodic DRM broadcasts for many years.
It appears unclear at this time however whether the current series of transmissions will soon end or be the start of a regular service.
Thus far, all of the latest test transmissions have taken place on 3560 kHz, which is actually allocated for amateur radio use.
According to radio enthusiasts in the region, the signal has been clear and very audible.
In 2012, 2016, and 2017, the country’s international service, The Voice of Korea, trialed DRM.
Those tests involved a professional grade DRM modulator, which identified itself as being from the Engineering Research Center of Digital Audio and Video (ECDAV) at the Communications University of China in Beijing.
Pyongyang Broadcasting Station, a Korean-language service for Koreans living in China, Japan, and South Korea, has been carrying out these latest broadcasts, which appear to implement two DRM modulators.
Based on settings and parameters, the first is the open-source, software-based Dream DRM transmitter.
Developed at Germany’s Darmstadt University some 15 years ago, technicians continue to tweak various parameters, such as bandwidth, as they test and learn about the system.
In spite of its age, the Dream DRM transmitter is compatible with any DRM receiver. North Korea could easily put on multiple DRM transmitters using this free system.
North Korean operators also appear to be using a professional-grade DRM modulator, which is most likely from private Chinese manufacturer Beijing Broadcasting Equipment Factory (BBEF). BBEF is best known for selling North Korea a number of shortwave transmitters ranging in power from 20 to 150 kW in 2011.
A professional DRM modulator is more capable than Dream. But North Korea probably cannot manufacturer its own and a single modulator can easily cost many thousands of dollars.
A lot has changed since North Korea last aired DRM broadcasts two years ago. Broadcasters in China and Guam have started regular DRM services and Russia is set to begin a service for Russia Far East.
With so many DRM programs coming on air in the region, North Korea may finally decide to remain on the air for good using the digital radio standard.