Category Archives: DRM

Mark explores North Korean DRM broadcasts over shortwave

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In the last issue of Radio Waves, we featured an article by Hans Johnson at Red Tech about DRM broadcasts originating in North Korea. This caused me to question exactly what these DRM broadcasts were (Voice of Korea?) and why they’ve chosen to use DRM as the mode. 

Of course, who really knows? North Korea isn’t public about any of their activities, so we rely on information from enthusiasts who have taken it upon themselves to investigate and confirm. Johnson assumed, “The most likely use [of DRM] would be as an audio feed to other stations and sites.” He used Radio New Zealand’s DRM service as an example, but I felt this to be unlikely with North Korea who doesn’t seem to use FM, MW, or shortwave relay sites in other parts of the world. 

Fortunately, our friend Mark Fahey is an expert on North Korean media, broadcasts, and propaganda. Mark is the author and curator of the dynamic Behind The Curtain project. 

I reached out to Mark via text message regarding North Korea’s use of DRM. Here’s what Mark shared with me earlier this week. This roughly follows the string of messages we exchanged.

Mark writes:

[October 3, 2022] I have been turning into the North Korean DRM today  on the new reported frequency in the [Red Tech] magazine: 6140kHz, though it’s not VOK, it’s a relay of 819kHz Pyongyang.

This service is called KCBS – Korean Central Broadcasting Service – it’s the main domestic service that is available on MW (a few FM outlets) and domestic SW across North Korea.

I will grab an audio ID off DRM for you at the top of the next hour – 0100 UTC. The DRM broadcast is only running one audio stream. It’s ACC audio 14.56kbps. As for purpose, maybe to feed the national AM relays, but also could be for North Korean ships, etc.

The other DRM frequency of 3205kHz is not on the air at the moment. I will check for it over the next 24hrs etc.

I just recorded the top of the hour. It was going in and out of DRM sync – I will send it now. I will grab a better sample tonight when there is a darkness path. The sun is well up in Pyongyang & Sydney at the moment (Noon Sydney – 10AM North Korea). Here is the Top Of The Hour ID from 10 minutes ago…

KCBS 6140 kHz (October 3, 2022)

I will record the station opening as well tomorrow morning – this domestic service also has an interval signal (the same tune as VOK–the first bars of “The Song (Hymn) of Kim Il Sung”). The opening is at 2000 UTC.

[October 4, 2022] OK here you go: both audio files (one from 6140kHz and the other from 3205kHz) are just from minutes ago as KCBS Pyongyang signed on. The signals go in and out of DRM lock here and this morning 3205kHz was the better–displayed at SNR at 13dB but still the DRM signal was breaking up.

Both DRM transmitters are running the same program: the main MW national service as heard on 819kHz in Pyongyang.

So I’m sure this DRM has nothing to do with the Voice Of Korea and is for domestic purposes.

I actually do not think it has anything to do with feeding remote transmitters as the DPRK has fibre and microwave links already in place for that purpose. I myself think it’s more likely intended for North Korean fishing vessels, navy, merchant shipping etc. But of course, nobody truly knows!

KCBS 3205 kHz (October 4, 2022)

KCBS 6140 kHz (October 4, 2022)

Thank you so much for your recordings and insight, Mark!

As I mentioned, Mark has a massive DPRK audio repository on his website Behind The Curtain. These are recordings you simply can’t find anywhere else, including hours of pristine Pyongyang FM recorded on a CC-Crane Witness Mark personally smuggled into Pyongyang.

In fact, the above photo is the CC Witness in Mark’s hand overlooking central Pyongyang.

Mark told me that the CC Witness was ideal–he used it on a number of content gathering trips to North Korea as it resembled an MP3 player or dictation recorder rather than a radio. Since it wasn’t suspected as being a radio recording device, it passed through the North Korean border each time without incident.

It’s an understatement to say that Mark took a number of risks to gather North Korean media from “Behind the Curtain.” Thank you, again, Mark, for sharing this info about DPRK DRM broadcasts.

Visit Behind the Curtain

Check out numerous recordings from North Korea in Mark’s archive.

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Radio Waves: WRMI Damaged by Ian, VOK Podcast, and North Korea Increases DRM

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Radio Waves:  Stories Making Waves in the World of Radio

Welcome to the SWLing Post’s Radio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!

Shortwave Station WRMI Damaged by Ian (Radio World)

The vast Okeechobee, Fla., antenna farm of privately-owned WRMI, which transmits programming to the world via shortwave radio, was hit hard by Hurricane Ian.

WRMI has 14 transmitters and 23 antenna systems. “We had winds up around 100 miles per hour, and that did a real number on our antenna field,” said Jeff White, general manager of WRMI.

“So far we have three antennas that are probably destroyed beyond repair: one to Europe, one to Africa and one to Central America and the South Pacific.”

As pressing as rebuilding these three antennas is for WRMI, “The biggest job we have at the moment is putting back up dozens of telephone poles that carry the transmission lines from the transmitter building to the antennas,” said White. [Continue read at Radio World…]

>>–Click here to donate to WRMI’s Hurricane Relief Fund.–<<

Voice of Korea programming available as a podcast

Many thanks to SWLing Post contributor, Alex, who notes that some of VOK’s language services are now available in podcast form. If you wish to hear some old school propaganda in high fidelity, this is a good way to do so: check it out on Castbox.

North Korea Doubles Digital Radio Output (Red Tech)

After years of experimentation, the famously secretive nation has switched on another DRM shortwave transmitter. The big question: Why?

Click here to read the full story in Red Tech’s latest issue (see page 12) or click here for page 12 only.

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Radio Waves: Fast Radio Bursts, Czechia DRM AM Trial, Kumartuli Radio Shop, and Ekho Moskvy Off Air

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Radio Waves:  Stories Making Waves in the World of Radio

Welcome to the SWLing Post’s Radio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!

Astronomers detect a radio “heartbeat” billions of light-years from Earth (MIT)

The clear and periodic pattern of fast radio bursts may originate from a distant neutron star.

Astronomers at MIT and universities across Canada and the United States have detected a strange and persistent radio signal from a far-off galaxy that appears to be flashing with surprising regularity.

The signal is classified as a fast radio burst, or FRB — an intensely strong burst of radio waves of unknown astrophysical origin, that typically lasts for a few milliseconds at most. However, this new signal persists for up to three seconds, about 1,000 times longer than the average FRB. Within this window, the team detected bursts of radio waves that repeat every 0.2 seconds in a clear periodic pattern, similar to a beating heart.

The researchers have labeled the signal FRB 20191221A, and it is currently the longest-lasting FRB, with the clearest periodic pattern, detected to date.

The source of the signal lies in a distant galaxy, several billion light-years from Earth. Exactly what that source might be remains a mystery, though astronomers suspect the signal could emanate from either a radio pulsar or a magnetar, both of which are types of neutron stars — extremely dense, rapidly spinning collapsed cores of giant stars.

“There are not many things in the universe that emit strictly periodic signals,” says Daniele Michilli, a postdoc in MIT’s Kavli Institute for Astrophysics and Space Research. “Examples that we know of in our own galaxy are radio pulsars and magnetars, which rotate and produce a beamed emission similar to a lighthouse. And we think this new signal could be a magnetar or pulsar on steroids.”

The team hopes to detect more periodic signals from this source, which could then be used as an astrophysical clock. For instance, the frequency of the bursts, and how they change as the source moves away from Earth, could be used to measure the rate at which the universe is expanding. [Continue reading…]

CRA Runs DRM Digital AM Trial in Czechia (Radio World)

Transmission company CRA looks at possibility for reusing analog transmission facilities

Czech transmission services company ?eské Radiokomunikace (CRA) is testing the DRM medium-wave digital radio system on 954 kHz.

According to a tweet from Marcel Prochazka, director of legal and regulatory affairs for CRA, the transmissions are originating from ?eské Bud?jovice in South Bohemia and operating at a power of 3.16 kW from a 107-meter HAAT antenna. Continue reading →

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Radio Waves: DRM Demo in Australia, Decoding the JWST, the ARDC, and EV Makers Dropping AM Radio

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Radio Waves:  Stories Making Waves in the World of Radio

Welcome to the SWLing Post’s Radio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!

Australia Demonstrates DRM on AM, FM (Radio World)

Since September 2020, ABC Radio has been quietly trialing DRM technology in Victoria

The public-service Australian Broadcasting Corp. and its transmission contractor BAI Communications Transmission Network hosted a public demonstration of Digital Radio Mondiale broadcasts on June 29, 2022. ABC highlighted the use of DRM on both AM and FM in Wagaratta, Victoria.

According to the DRM Consortium, the demonstration was the culmination of almost two years of COVID-impacted work to assess the performance of DRM services in Australia’s VHF and medium-wave bands.

Previously, the Australian Amateur Radio Experimenters Group reported that AREG member Steve Adler (VK5SFA) had been monitoring “a very un-publicized Digital Radio Mondiale (DRM) trial” on 747 kHz from Wangaratta in August 2021.

The Australian Communications and Media Authority provided ABC with a license variation to conduct the DRM 30 trials from September 1, 2020, to August 31, 2022.

At the public demonstration, senior representatives from the public, commercial and community radio sectors, along with regulators and other interested parties, were able to hear and see the capabilities of DRM broadcasting on AM from Dockers Plains and on FM from Mount Baranduda. They were also able to review the transmission equipment at Wagaratta.[Continue reading…]

Also check out the DRM Consortium’s article on this same topic.

Decoding James Webb Space Telescope (Daniel Estévez)

The James Webb Space Telescope probably needs no introduction, since it is perhaps the most important and well-known mission of the last years. It was launched on Christmas day from Kourou, French Guiana, into a direct transfer orbit to the Sun-Earth L2 Lagrange point. JWST uses S-band at 2270.5 MHz to transmit telemetry. The science data will be transmitted in K-band at 25.9 GHz, with a rate of up to 28 Mbps.

After launch, the first groundstation to pick the S-band signal from JWST was the 10 m antenna from the Italian Space Agency in Malindi, Kenya. This groundstation commanded the telemetry rate to increase from 1 kbps to 4 kbps. After this, the spacecraft’s footprint continued moving to the east, and it was tracked for a few hours by the DSN in Canberra. One of the things that Canberra did was to increase the telemetry rate to 40 kbps, which apparently is the maximum to be used in the mission.

As JWST moved away from Earth, its footprint started moving west. After Canberra, the spacecraft was tracked by Madrid. Edgar Kaiser DF2MZ, Iban Cardona EB3FRN and other amateur observers in Europe received the S-band telemetry signal. When Iban started receiving the signal, it was again using 4 kbps, but some time after, Madrid switched it to 40 kbps.

At 00:50 UTC on December 26, the spacecraft made its first correction burn, which lasted an impressive 65 minutes. Edgar caught this manoeuvre in the Doppler track.

Later on, between 7:30 and 11:30 UTC, I have been receiving the signal with one of the 6.1 metre dishes at Allen Telescope Array. The telemetry rate was 40 kbps and the spacecraft was presumably in lock with Goldstone, though it didn’t appear in DSN now. I will publish the recording in Zenodo as usual, but since the files are rather large I will probably reduce the sample rate, so publishing the files will take some time.

In the rest of this post I give a description of the telemetry of JWST and do a first look at the telemetry data. [Continue reading…]

Helping Secure Amateur Radio’s Digital Future (Hackaday)

The average person’s perception of a ham radio operator, assuming they even know what that means, is more than likely some graybeard huddled over the knobs of a war-surplus transmitter in the wee small hours of the morning. It’s a mental image that, admittedly, isn’t entirely off the mark in some cases. But it’s also a gross over-simplification, and a generalization that isn’t doing the hobby any favors when it comes to bringing in new blood.

In reality, a modern ham’s toolkit includes a wide array of technologies that are about as far away from your grandfather’s kit-built rig as could be — and there’s exciting new protocols and tools on the horizon. To ensure a bright future for amateur radio, these technologies need to be nurtured the word needs to be spread about what they can do. Along the way, we’ll also need to push back against stereotypes that can hinder younger operators from signing on.

On the forefront of these efforts is Amateur Radio Digital Communications (ARDC), a private foundation dedicated to supporting amateur radio and digital communication by providing grants to scholarships, educational programs, and promising open source technical projects. For this week’s Hack Chat, ARDC Executive Director Rosy Schechter (KJ7RYV) and Staff Lead John Hays (K7VE) dropped by to talk about the future of radio and digital communications. [Continue reading…]

Interference causes EV makers to drop AM radio (Radio World via the Southgate ARC)

Radio World reports the Electromagnetic Interference generated by Electric Vehicles is causing some EV automakers to drop AM (medium wave) radio

The article says:

Some EV automakers are dropping AM altogether due to audio quality concerns, but that’s just one piece of the puzzle as radio continues to fight for space on the dash.

“As carmakers increase electric vehicle offerings throughout their lineups, the availability of AM radio to consumers is declining,” said Pooja Nair, communications systems engineer with Xperi Corp., in a Radio World guest commentary. “This is because the effects of electromagnetic interference are more pronounced in EVs than in vehicles with internal-combustion engines.”

In other words, electromagnetic frequencies generated by EV motors occupy the same wavelength as AM radio signals. The competing signals clash, effectively cancelling each other out. As EV motors grow more powerful, AM static tends to increase.

Read the full story at
https://www.radioworld.com/news-and-business/headlines/why-are-some-automakers-ditching-am-radio

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Changes to KTWR’s DRM broadcast schedule effective 3rd July, 2022

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Many thanks to SWLing Post contributor, Mangosman, who shares the following tip from Mike Sabin at KTWR via Alokesh Gupta’s blog:

Due to requests for later broadcasts, improved propagation, and the addition of a program, KTWR is changing its DRM broadcast schedule effective 3rd July, 2022.

KTWR Digital Broadcasts
DRM broadcasts (Effective 3rd July 2022):

Day Time(UTC) Frequency Coverage Area Language
—————————————————
Saturday 1100-1127 12000 kHz China English
Saturday 1128-1230 9910 kHz Japan Japanese, English
Mon-Fri 1215-1245 9910 kHz China Mandarin
Sunday 1500-1545 15205 kHz India English
Sunday 1600-1630 15390 kHz India South Indian languages

(Mike Sabin, KTWR)

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Jerome would like to know more about the Starwaves Truckbox DRM converter

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Many thanks to SWLing Post contributor, Jerome van der Linden, who writes:

Hello Thomas,

Back in January 2019 you featured in SWLing an item about a portable DRM/DAB receiver produced by Starwaves GmbH.

It seems the same company had also produced a DRM/DAB to FM convertor for use in trucks and cars, as this Youtube Link shows:

Click here to view on YouTube.

It shows the unit tuned to 6095khz and later to 13810khz, with music being played, I assume via the converter and transmitted on a free FM frequency the car radio is tuned to.

The video also shows a couple of shots of the converter and remote control, and a second bit of hardware that I’m unsure of its function. This was all back in 2007, I gather. The comments from those that have seen the video are not I suspect from people familiar with SW listening, and the suspicion that a car whip antenna is entirely unsuited to SW reception should be questioned, as I had personal experience of this while in Saudi Arabia in 1990, where SW car radios were not uncommon, and strong signals provided perfectly acceptable audio quality. Sure, 1 metre long whip won’t be much good for SW DX, but who’s going to be doing that while driving a car?
Anyway, I’m curious to know if anyone has ever purchased a Starwaves Truckbox? I gather it is currently not available.

73s
Jerome van der Linden

Thanks for sharing this, Jerome. I, too, am curious if the Starwaves Truckbox made it beyond the prototype stage to be mass produced. Please comment if you have more info!

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Voice of Korea via Digital Radio Mondiale (DRM)?

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Many thanks to SWLing Post contributor, Paul Jamet, who writes:

Hi Thomas,

Several listeners have posted videos on YouTube about receiving broadcasts of “The Voice of Korea” on 6140 kHz DRM – Digital Radio Mondiale.

One video in particular caught my attention, from Indian listeners in the Kerala region:

Indeed, these headphones use a Chinese receiver, the G-226 from GOSPELL which is also sold by TECSUN in Australia: https://www.tecsunradios.com.au/store/product/tecsun-drm-radio/

So, you can see how this receiver works.

All this has aroused my curiosity! And yesterday, Friday 17 June 2022, at 20:00 UTC I connected to several kiwi SDRs in the Pacific area. The DRKP signal could be picked up almost 8,000 km from the transmitter site near Pyong-Yang.

Here attached a screenshot and an audio file recorded with a kiwi SDR located a few kilometres away near Perth, Australia – Distance according to Google Maps, about 7960 km

The signal is encoded in AAC and not xHE AAC

[Audio: Note that the audio level jumps several times, so don’t turn up the volume too high.]

Who is this program for? According to Indian radio listeners, probably to the North Korean fleet in the Pacific. To be continued.

Have a nice weekend. Yours sincerely

Paul JAMET

I would have never guessed VOK would broadcast in DRM. Very interesting indeed. Perhaps we’ll learn more about this with time or someone can confirm whether or not this is actually VOK. Thank you for sharing this, Paul!

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