Category Archives: DRM

Radio Waves: Antenna ID, DRM Receiver Requirements Revisited, BBC Broadcasting Technology, and Digital Sound Broadcasting Framework in Kenya

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!


Identify that antenna by sight (Hackaday)

It’s a skill that radio amateurs pick up over years but which it sometimes comes as a surprise to find that is not shared by everyone, the ability to casually glance at an antenna on a mast or a rooftop and guess what it might be used for. By which of course I mean not some intuitive ability to mentally decode radio signals from thin air, but most of us can look at a given antenna and immediately glean a lot of information about its frequency and performance. Is this privileged knowledge handed down from the Elmers at the secret ceremony of conferring a radio amateur’s licence upon a baby ham? Not at all, in fact stick around, and I’ll share some of the tricks. [Continue reading…]

Minimum Receiver Requirement Document Revisited (DRM Consortium)

The latest version of the document (mrr.drm.org) describes the DRM (Digital Radio Mondiale) receiver characteristics for consumer equipment intended for terrestrial reception operating in the frequency bands below 30 MHz (i.e. DRM robustness modes A to D) and also those for the frequency bands above 30 MHz (i.e. DRM robustness mode E). The goals of the document are to: provide guidelines to receiver manufacturers for minimum receiver performance and technical features, to offer confidence to broadcasters that their DRM transmission can be received by all receivers in the market, to assist broadcasters to plan their network and to give full confidence to consumers that all important DRM features are supported by receivers and all DRM transmissions can be received when they acquire a digital DRM receiver.

Click here to download (PDF).

BBC broadcast tech: then and now (Engineering and Technology)

In its centenary year, we look at the BBC’s pivotal role in making the broadcast and radio technology field what it is today.

Daily London broadcasts by the newly formed British Broadcasting Company began from Marconi House on The Strand, on 14 November 1922, using the call sign 2LO, with transmissions from Birmingham and Manchester starting on the following day.

The first broadcast by the young company, which was heard as grainy, muffled speech, was read by Arthur Burrows, who joined the BBC as director of programmes. Notably, he was one of the first people to move from newspaper to broadcast reporting.

At the end of 1922, Scottish engineer John Reith, who was just 33 years old at the time, was appointed general manager of the BBC, which then had a staff of four. Reith is remembered for establishing the tradition of independent public service broadcasting in the United Kingdom.

Within months, the growing organisation moved into the same building as the Institution of Electrical Engineers at Savoy Hill (now the IET’s Savoy Place event venue), where it continued to expand. This was an obvious home for the young BBC, and for the next nine years this is where early innovations of broadcasting occurred.

The British Broadcasting Corporation, as it is known today, was established in January 1927 as a public corporation, and in 1934 it moved from Savoy Hill to the purpose-built Broadcasting House in Portland Place. [Continue reading…]

CA plans digital radio shift on shortage of frequencies (Business Daily Africa)

Kenyan broadcasters will be allowed to adopt a new digital radio standard, which will enable them to use their current spectrum to transmit their signals through a digital network, as the sector regulator moves to address the shortage of analogue frequencies.

The Communications Authority of Kenya (CA) has called for stakeholder and public views on a draft Digital Sound Broadcasting (DSB) framework it has formulated to ensure the efficient use of the available broadcasting spectrum and encourage investment in the sub-sector.

“The objective of this consultation is to develop a suitable framework for Digital Sound Broadcasting in Kenya to address the challenge of high demand and low availability for analogue FM broadcasting frequencies that is currently being experienced,” said the CA. [Continue reading…]


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Reception Reports Requested: “One-Off” DRM Broadcast From Woofferton To India Today

Many thanks to SWLing Post contributor, Mangosman, who shares the following announcement from the DRM Consortium:

Encompass Plans A One-off Broadcast From Uk To India On Nov 4th

Encompass Digital Media will be running a one-off transmission from its site in Woofferton, UK, on Friday 4th of November. This electronic music broadcast will target the whole of India, around 5,000 miles (or about 8,000 kilometres) as the crow flies to the centre of the country. This might be the longest distance Encompass has covered with its DRM transmissions.

Before the actual broadcast, several tests were run using different frequencies, antennas and power combinations. The final test on November 2nd to confirm final set-up was a great success as the audio could be recorded from a KiwiSDR online receiver located in New Delhi. The SNR of 20dB was measured in New Delhi and 23.9dB in Bangalore, which proves the power of shortwave radio and how DRM and its excellent sound, even in shortwave, can travel such long distances. The audio was also decoded in Bangkok, and a listener report came even from Canada!

This experimental broadcast promoting the music of C. M. Obrecht is scheduled for tomorrow [today Nov 4 at time of publishing], 19:00 – 20:00 UTC, on 11710kHz. It will use xHE-AAC codec with DRM Mode B, transmitting at 125kW on a 78* bearing from Woofferton. The audio will be accompanied by ancillary data including a slideshow image of the album cover art.

Although the transmission time will mean it will be quite late in India, Encompass is interested in receiving any reception reports from within the country, particularly from anybody using a car radio. Please send reception reports to Steve Palmer at: [email protected] (This is also the address to use for further information about Encompass’ DRM projects and services).

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Radio Waves: BBC Centenary, RNZ Continues DRM Investment, Hurrican Ian Help from a Ham, and Philips 353A Restoration,

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!


BBC centenary marked at first national radio transmitter (BBC News)

The BBC’s 100th anniversary has been marked in the town that enabled it to make nationwide radio broadcasts.

Opening on 27 July 1925, the Daventry Transmitter was the world’s first long wave transmitting station.

Known as 5XX, it was on Borough Hill in the Northamptonshire town and its first transmission was with the a poem called “Daventry Calling…”.

Sophie Good from the town’s museum said: “Daventry has got a strong affiliation with the BBC.”

The BBC chose the position so the transmitter could cover the maximum land area.

It brought the total audience within listening distance to 94% of the population.

When it opened, the poem by Alfred Noyes was followed by speeches from the postmaster general, external and the mayor of Daventry, introduced by Lord Gainford, BBC Chairman.

The then Prime Minister Stanley Baldwin sent a message, published in the Radio Times, which said he saw “Daventry as another milestone on the road to the social betterment of our people”. [Continue read at the BBC…]

The BBC is celebrating its 100th birthday (NPR / AP)

LONDON — The British Broadcasting Corp. marked 100 years of broadcasting on Tuesday, a century after a group of wireless manufacturers founded the company and began filling the airwaves with its first daily radio service.

The BBC was founded on Oct. 18, 1922, in London and daily broadcasting began a month later. The broadcaster is marking its centenary with a series of special programs, including a guest appearance from King Charles III on The Repair Shop, a program featuring expert craftspeople restoring antiques.

Actress Jodie Whittaker will make her last appearance as the Time Lord on a special episode of Doctor Who on Sunday, before Ncuti Gatwa takes over the role. [Continue reading…]

DRM Member Ampegon Wins a New Shortwave Transmitter Contract with RNZ (DRM Consortium)

In September 2022, Ampegon Power Electronics AG and RNZ (New Zealand public broadcaster) signed a contract to supply a new TSW2100-V4 100 kW shortwave transmitter to New Zealand. The transmitter will broadcast the RNZ Pacific service to millions of people living across the Pacific with high reliability and energy efficiency: Ampegon wins a new Shortwave Transmitter Contract with RNZ – Ampegon.

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Mark explores North Korean DRM broadcasts over shortwave

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

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?


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

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

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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