How digital radio could break North Korea’s information blockade

Software-defined radio might prove valuable for increasing information flows into and out of N. Korea
March 17th, 2014

While North Korea recently ranked second-to-last on Reporters Without Borders’ World Press Freedom Index, new ways of using digital radio broadcasting might prove a valuable tool for those who wish to increase information flows into and out of the country.

So-called software-defined radio (SDR) technology, brought into the country on USB devices, could be used for receiving and, potentially, sending data – text, audio and video files – on radio band frequencies.

SDR technology is a radio communications system where all components typically implemented via hardware for standard radios have been made into software. Loaded onto a flash drive-sized USB-dongle, they have the potential to turn any computer with a USB port into a receiver and transmitter. 

Radio experts and NGO representatives said that something like this might have potential as a new way of bringing information into North Korea, and in certain cases provide a tool for citizen reporters working inside the country to bring information out.

“Radio experts and NGO representatives said that something like this might have potential as a new way of bringing information into North Korea”


By using so-called digital radio modes, data files such as pictures, text and video can be easily embedded into radio transmissions, an SDR dongle developer explained to NK News. The setup would include the USB dongle, the required software and drivers, and a computer, allowing the broadcasted files to be saved to a drive for later viewing.

“With a (digital) mode like DRM+ (Digital Radio Mondiale), that is something that could be done,” said the developer, who requested anonymity. “With bitrates of up to a hundred kilobytes per second it could provide a streaming video, but it wouldn’t be very high-quality if it is real-time. It would essentially be slightly more than an ISDN connection

He said that there are two likely options for setting up such transmissions into North Korea: using VHF bands coupled with satellite, or using short-wave (SW) frequencies combined with so-called spread spectrum technology.

Short-wave signals bounce off the ionosphere and therefore have longer ranges, allowing broadcasters to transmit from abroad, but they are more susceptible to being jammed by authorities.

“To circumvent that you would have to use spread spectrum,” said the developer. With spread spectrum technology, the signals hop between frequencies within a given range according to a predefined algorithm, and is therefore less susceptible to frequency jamming. The software on the receiving end compiles the signals sent on the different channels and puts it back together.

VHF is line-of-sight transmission, meaning it has shorter range and would need to be amplified via satellite to obtain sufficient range.

However, “VHF on satellite would be quite hard to jam, because the authorities would either have to cover the whole country with jammers, or they would have to put their own satellite up to jam it, which would be costly and require geostationary technology, which I don’t believe North Korea has,” the developer said.

Even with low-earth satellites, which orbit the earth only every few minutes, they would only be able to jam it occasionally, he said.

It would also require anyone who wants to transmit into North Korea to get the project sanctioned by a government or commercial actor, letting the broadcaster make use of their satellites.

“One-thousand words of text might transfer within a few seconds”

Thomas Witherspoon, radio ham and director of tech- and radio-NGO Ears To Our World, told NK News that the type of frequencies utilized would also determine how much data could be sent in a given time period. SW transmissions have long range but low power, so that “a simple HF transceiver might be able to move a message accross the border from anywhere within North Korea, but 1,000 words of text might take several minutes to transfer,” he said. However, “VHF or UHF frequencies, on the other hand, allow for much wider bandwidth, thus less transmitting time and more reliability. One-thousand words of text might transfer within a few seconds.”


Computing in Korea | Picture: Eric Lafforgue


If certain challenges could be overcome, the idea could significantly impact the information landscape in North Korea, said Mark Freeman, who recently presented the “Behind the Curtain” project on North Korea’s media environment.

“Any way that electronic information can come in is just going to be incredible. And the idea of having citizen journalists sending things out would also be amazing. These are the sort of things that can radically change a country,” he said.

“Regarding transmitting from inside North Korea – this is a long way into the future, but imagine there are groups inside the country who would be interested in broadcasting independent media themselves. It’s a long way into the future, but now, many things that were unavailable a decade ago are today possible.”

“The idea of having citizen journalists sending things out would also be amazing. These are the sort of things that can radically change a country”

Witherspoon of Ears to Our World suggested that while a certain amount of R&D would be required, it could be done with the proper combination of funding and backing.

“I believe it’s viable,” he said. “With a little innovation and support from a visionary NGO, this simple communications tool could quickly become a reality.”

SDR dongles currently on the market, such as the RTL-SDR or FUNCube dongles, are priced from $20 and up, but a tailored setup would need to be developed for this specific case, taking into account the need for concealment, the specific frequencies to be used, and North Korea’s computer ecosystem.

While technically feasible, several sources pointed out that the challenges for such a project would be significant. Hardware and software still has to be physically brought into North Korea and, particularly if it were to be used for transmitting from inside the country, the risks of being caught could be high, because local signals could be detected and pinpointed fairly easily by authorities.

“The risks of being caught could be high, because local signals could be detected and pinpointed fairly easily by authorities”

“There are ways of doing things in a more covert manner. But in the end, as soon as you’re transmitting stuff, by its very nature, it is being broadcast, even if it’s intended to be received by someone specific,” the SDR-developer said, adding that it would also require significantly higher technical literacy from the user, because the computer would need to be modified to give it transmitting capabilites. The signal would be weak and require amplification, even as those who use it still would have to be fairly close to each other.

And even for merely receiving signals, the risks might be higher than they are for those North Koreans who today listen to foreign broadcasts on standard radio devices. According to Nat Kretchun, co-author of the 2012 InterMedia report “A Quiet Opening” on changes in North Korea’s media environment, standard radios “are relatively good devices to avoid inspections because they are either easy to hide or can be passed off as legal,” whereas computers are subject to greater scrutiny than many other devices.

“There may also be a more easily traceable record of what the computer was used for,” he said.


Since the dongles must be coupled with a computer with the appropriate software, there is also the question of listenership. The 2012 InterMedia report, citing a 2010 Broadcasting Board of Governors (BBG) survey of 250 recent defectors, notes that 16 percent had access to computers. However, Kretchun also pointed out the importance of secondary listenership when assessing potential impact.

“Most North Koreans get most of their non-official news through rumors and word of mouth, and radio is certainly a source that seeds a lot of word of mouth,” he said. The BBG survey estimates direct listenership to foreign radio broadcasts at 27 percent, and notes that only 32 percent of the respondents said they “did not share with anyone” from what they had heard, whereas those who did share did so with friends and neighbours (44 percent), immediate family members (28 percent) or colleagues (4 percent).

“The biggest problem is how to get the equipment inside North Korea. Once this is solved all the other problems are less than none”

The biggest challenge to realizing such a project would be logistic rather than technical, suggested Park Sang-hak, chairman of Fighters For A Free North Korea, an NGO that has organized several balloon-launches from across the North-South border. “The biggest problem is how to get the equipment inside North Korea. Once this is solved all the other problems are less than none,” he told NK News last week, noting that it would probably require assistance from someone inside North Korea.

Kretchun of InterMedia said that the entry barriers might be higher than for, say, balloon-launches carrying USB-sticks and DVD’s, but that “for those who could overcome the barriers, receiving the information would be much more efficient, reliable, cheap and potentially safer,” adding that the content provided could be more in-depth.

“Balloons generally carry fliers with simple messages,” he said.

Additional reporting by JH Ahn.

Picture: Ole Jakob Skatun

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About the Author

Ole Jakob Skåtun

Ole Jakob Skåtun is a freelance journalist. In addition to reporting on Korean affairs for newspapers in his native Norway, his previous work also includes freelance work from Russia. His Twitter handle is @OleJakobS