Tag Archives: Digital Radio Mondiale

All India Radio suspends shortwave and “pure DRM’ transmissions during Covid-19 lock-down

Photo by Karthik Chandran

Many thanks to SWLing Post contributor, Mark Fahey, who notes that All India Radio has suspended a number of their broadcast services during the Covid-19 lock-down.

Mark shares the following Office Memorandum from India’s Public Service Broadcaster.

Click here to download memorandum (PDF).

In terms of shortwave (ESD) services, here’s the relevant section from the Memorandum:

B) NON-ESSENTIAL RADIO SERVICES

The following non-essential radio services may be suspended with immediate effect during the lock-down

ESD

5) All ESD services

6) All transmitters dedicated to ESD

DRM

7) Pure DRM mode operations

a. DRM transmitters may be operated on analogue / simulcast mode to relay the National News Service subject to local circumstances and conditions

FM

8) Stations with a 3rd FM channel may relay audio of DD News or DD India subject to feasibility

On the WRTH Facebook group, Sanjay Sutradhar, did note one shortwave broadcast still in service:

It appears 9380 kHz from Aligarh is radiating AIR Vividh Bharti services, may be on a truncated wattage. 8am & 8.30pm news is extended to one hour dedicated to Covid-19 news in-country and world-wide and developments but it is the common broadcast carried out in-country on all bands, at 1.45 UTC

Mark Fahey asks:

I wonder if they will ever bring AIR’s External Service back–?

That’s the big question, isn’t it? The government lock-down is set for 21 days, but I fully expect it could take much longer if other Covid-19 countries are any indication.

If AIR’s shortwave service is closed for an extended period of time–recognizing they deem it “non-essential”–I wouldn’t be surprised if they made deep cuts or keep it closed. Let’s hope for the best outcome, though.

Stay tuned! We’ll keep you updated.


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Radio Waves: Plant-powered Satellite Comms, BBC Pips, Filter Basics, and Replacing Shortwave

Radio Waves:  Stories Making Waves in the World of Radio

Because I keep my ear to the waves, as well as receive many tips from others who do the same, I find myself privy to radio-related stories that might interest SWLing Post readers.  To that end: Welcome to the SWLing Post’sRadio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!

Many thanks to SWLing Post contributors Marty, Dennis Howard, Dennis Dura, Kris Partridge and Richard Langley and for the following tips:


Plant-powered sensor sends signal to space (Phys.org)

A device that uses electricity generated by plants as its power source has communicated via satellite—a world first.

[…]The device can inform farmers about the conditions of their crops to help increase yield, and enable retailers to gain detailed information about potential harvests.

It transmits data on air humidity, soil moisture and temperature, enabling field-by-field reporting from agricultural land, rice fields or other aquatic environments.

The extremely low power device sends signals at radio frequencies that are picked up by satellites in low Earth orbit. It was developed by Dutch company Plant-e and Lacuna Space, which is based in the Netherlands and the UK, under ESA’s programme of Advanced Research in Telecommunications Systems (ARTES).[]

The eccentric engineer: a tale of six pips and how the BBC became the national arbiter of time (Engineering and Technology)

This edition of Eccentric Engineer tells the story of the BBC Time Signal and how, over the years, it has just got more complicated.

Every engineer needs to know the time, if only so as to not miss lunch. Since 1924, many Britons have been checking their watches against the BBC time signal, known affectionately as ‘the pips’.

The history of the ‘pips’ is almost as long as the history of the BBC itself. The first transmissions from what was then the British Broadcasting Company began in late 1922 and soon afterwards there were suggestions of broadcasting a time signal under the control of the Royal Observatory at Greenwich – then the arbiter of time in the UK.

No one seems to have seen a need for this degree of precision, but early broadcasts did use their own ad hoc ‘pips’, marking the 8pm and 9pm news programmes with a time signal consisting of the announcer playing the Westminster chimes on a piano and later a set of tubular bells. This proved rather popular with listeners, who could now adjust their clocks and watches daily, so the BBC decided to invest in some more high-tech clocks from the Synchronome Company. These provided audible ‘ticks’, which the announcer then simply counted down.[]

What Is Replacing Shortwave? (Radio World)

A joint effort is necessary to bring the digitization of radio to a successful end

Analog shortwave will celebrate about 100 years of existence in 2028 when many hope 5G will have been properly defined, tested and applied, though broadcasting is low on its long list of perceived advantages.

It’s true that shortwave was typically a medium of the Cold War that peaked in 1989 and that afterward its listenership dwindled. Many international broadcasters gave up on it as the post-war transmitters got rustier and the energy bills kept mounting.

After all, when budget cuts are needed, no transmitter will go on strike or write to the press, as happened when the BBC World Service tried to unsuccessfully close its Hindi shortwave transmissions in 2011. In 2020 these broadcasts stopped, when committed BBC Indian listeners, writers and thinkers who opposed it in 2011 did not protest too much.

The slow death of shortwave has been blamed on the internet and satellite. As technology and content are inextricably linked, shortwave created its type of content that is no longer favored by the savvy FM listener, internet user and cellphone obsessed.[]

Filter Basics: Stop, Block and Roll(off) (Nuts and Volts)

A casual observer might think that wireless systems consist primarily of filters connected by the occasional bit of circuit! Block diagrams of transceivers often include as many filters as any other function. This is true at the system level, just as it is at the circuit level — and many circuits behave in a filter-like way, whether intended to be a filter or not! That makes understanding filter basics important for wireless success.[]


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Radio Marti now on DRM: Seeking your listener reports!

Many thanks to Edward R. Murrow Transmitting Station Chief Engineer, Macon Dail, who shareds the following announcement regarding their Radio Marti broadcasts:

We just powered up our 50 kW transmitter using DRM.

We are on a frequency of 7345 kHz and will be on daily from 1700-0200 UTC. We would love hearing from anyone that is able to copy and decode our transmissions.

The broadcast contain two audio programs.

Post Readers: If you successfully receive and decode a Radio Marti DRM broadcast, please send your detailed listener report to:  gstraub@usagm.gov This is certainly a unique opportunity to log a North American DRM broadcast!

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AM Revitalization: DRM Consortium asks FCC to adopt DRM

Many thanks to SWLing Post contributor, Alan, who shares this editorial from Radio World that features edited comments filed with the FCC by the DRM Consortium.

The following unedited letter was taken directly from the FCC comments database:

(Source: FCC Filing [PDF])

In your document (FCC19-123) you rightly highlight the great advantage of AM broadcasts, primarily the ability to cover large areas and number of listeners, while the band itself is losing popularity because of a variety of issues to do with propagation, interference, environmental changes. At the same time, digital audio broadcasting is no longer the new platform it was in 2002. At that time FCC mandated a proprietary system (IBOC, “HD radio”) as the only system to be used in the USA with the possibility of applying DRM for HF.

Since then DRM (the ITU recommended, only digital audio broadcasting for all bands, open standard, has been tested and used all over the world on all bands, short wave, medium wave and FM).

So while you are recommending now pure digital HD, based on the NAB tests and WWFD not completely convincing trial, we would urge the FCC to consider opening the straightjacket of 2002 and allow DRM to be used as a sure, tested, efficient way of digitizing the AM band.

There are several reasons for this:

DRM digital radio delivers in the AM bands significant benefits:

    • Audio quality that is on par or better than FM. DRM of all recognized digital
      standards is the only one using the ultra-efficient and compressed xHE-AAC audio
      codec that delivers at even very low bit-rates exceptional audio quality for speech
      but music, as well. (https://www.drm.org/listen-compare/)
    • Record Data: DRM has been tested in medium wave all over the world in both
      simulcast and pure digital. A list of the main tests (some of which have become ITU
      adopted documents) are included in Annex 4 of the DRM Handbook:
      https://www.drm.org/wp-content/uploads/2019/02/DRM-Handbook.pdf
      At the moment, 35 MW transmitters are on air in simulcast or pure DRM in India.
      http://prasarbharati.gov.in/R&D/
    • Auxiliary Data. DRM is the newest, most complete, open standard for digitizing radio in
      all frequency bands, and is recommended by ITU. DRM has been devised as a direct
      heir to analog AM (SW, MW). It uses 9/10, 18/20 kHz bandwidth and has a useful content
      bit rate of up to 72kbps. It carries up to 3 programs on one frequency and one data channel, while data can be carried on each of the audio channels as well. One of the great advantages of DRM is that alongside excellent audio, the receiver screens will display visual information of any kind required (albums’ titles, singers’ photos, maps, visuals of any sort, data of any kind). The Journaline application allows for extra information from the internet or the RSS feeds of the broadcaster to be captured and displayed. Currently broadcasters like the BBC, All India Radio, KTWR in Guam are using this extra facility that clearly differentiates digital form analog as a superior option.
    • Power/energy efficiency. Using SW or MW in DRM can reduce the power used up
      to 80%). As per calculations made by Ampegon, a medium wave transmitter can
      cover an area of 235000 sq km with a 100kW transmitter. The DRM EPR of such a
      transmitter is about 50kW and the coverage area is the same, while instead of one
      analog programme up to three digital channels and one data channel can be
      broadcast, all in excellent audio quality.
    • Spectrum efficiency (more programmes can be broadcast on one single frequency
      used for one programme in analog) as explained above.
    • DRM, unlike analog, offers enhanced and stable audio quality that is FM-like
      (mono or stereo). DRM also offers multiservice data enabled by applications like
      Journaline (the enhanced text services, more information captured as RSS feeds or
      form other internet source), slideshows, multilingual text (practically being able to
      show any characters of any language not just Latin script), and the Emergency
      Warning Functionality (EWF) in case of disasters.
    • Interference. This has not been noted as the DRM signal will always be lower than
      the analog one. AIR has not noted any interference in its operation of DRM
      transmitters. The mask values required for an optimal functioning of DRM
      transmitters is clearly stipulated in the ITU documents and as long as the network
      planning is correct, and the mask is respected there should not be any issue of
      interference in digital-analog or digital-digital DRM transmissions.
    • Receivers. Currently there are several receiver models and SDR options for the
      reception of DRM in AM. India has almost 2 million new cars fitted with DRM
      receivers, at no cost to the buyers, that are capable of and are receiving DRM
      mediumwave signals. The audio quality is excellent and a sure benefit to the users.
    • DRM is in direct succession to the analog AM (and FM) services, not owned or
      controlled by any single company and immediately available with full know-how and
      technology access by the transmitter and receiver industry.
    • As HD in mediumwave is a bit of a necessary step but still a leap in the dark, it
      would make sense from the practical aspects and even receiver solution availability
      to allow DRM as the best, clearly proven solution of digitizing the AM band (in
      preference or alongside HD) in the US.

In short, the salient advantages of DRM are:

    1. The audio quality offered by DRM is equally excellent on all the transmission bands:
      MW, SW or VHF
    2. Robust signal unaffected by noise, fading or other forms and interference in all bands
    3. Clear and powerful sound quality with facility for stereo and 5.1 surround
    4. More audio content and choice: Up to two and even three audio programmes and one
      data channel on one frequency
    5. Extra multimedia content: Digital radio listeners can get multimedia content
      including audio, text, images and in future even small-scale video, such as:

      • Text messages in multiple languages
      • Journaline – advanced text-based information service supporting all classes of
        receivers, providing anytime-news for quick look-up on the receiver’s screen;
        interactivity and geo-awareness allowing targeted advertising
      • Electronic Programme Guide (EPG), showing what’s up now and next; search
        for programmes and schedule recordings
      • Slideshow Programme accompanying images and animation
      • Traffic information
    6. Automatically switch for disaster & emergency warnings in case of impending
      disasters in large areas, automatically presenting the audio message, while providing
      detailed information on the screen in all relevant languages simultaneously. Great
      potential to become the surest and widest means of alerting the population to
      emergencies.

Therefore, we urge FCC to take a wide view and consider all options including DRM, if AM is worth futureproofing in the USA.

[This filing also included a number of “Useful Press Links]

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DRM30 on a Smartphone: KTWR Shows Us The Way

Image via the KTWR Blog

Many thanks to SWLing Post contributor, Dan Van Hoy, who writes:

[Regarding the reception of DRM via smart phone,] I happened to find this KTWR Guam post about decoding DRM30 with a smart phone, app, and an RTL-SDR:

Convert Smart Phone to DRM 30 HF receiver!

We are pleased to report successful use of an SDR Dongle used to directly receive and Decode DRM 30 over HF today.

The SDR Dongle is an RTLSDR v3 type connected to an android smartphone using an OTG cable (phone or tablet must be OTG capable).

The Software used:
1. Android driver (free)
2. DRM+SDR Android App ($4.99)

The Frequency of the HF broadcast is directly assigned within the DRM+ SDR app with two settings
1. Frequency in Hertz
2. RF Gain (0-512)

Demonstration video showing Clean DRM decode of AAC Audio and Journaline data along with live metadata.  (our signal was very strong, so only a short wire used for Antenna, DX’rs will need an appropriate Antenna)

Now anyone with a smartphone and a $20 SDR can receive DRM 30 HF broadcasts…

Click here to read this post on the KTWR blog.

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Tim Whittaker explains route from proof of concept to development of low-cost DRM receiver

Many thanks to SWLing Post contributor, Ed, who writes:

Here’s some new news about low-cost DRM receiver advancement, and links to an audio presentation explaining the route from proof of concept to development of a low-cost prototype DRM receiver by Cambridge Development. SWLing Post readers might find it interesting:

(Source: DRM Consortium)

16 Jan Low-cost DRM Receiver Advancement

DRM member Cambridge Consultants recently announced an under 10 USD prototype DRM receiver, which was reported in our Newsletter and widely in the industry press. The prototype receiver was unveiled during an Innovation Day at their offices in the UK. Neale Bateman, Encompass Digital Media and a member of the DRM Steering Board, attended the event and spoke to company representative, Tim Whittaker, to find out why the interest in producing this type of DRM receiver. Listen here

Tim also explained the route from proof of concept to development that has helped Cambridge Consultants to produce this low-cost prototype DRM receiver.  Listen here

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KiwiSDR update brings integrated DRM reception!

Many thanks to SWLing Post contributor, Mark Fahey, who shares the following tweet from KiwiSDR:

“Happy Holidays. Software update brings integrated DRM receiver (Digital Radio Mondiale) based on Dream 2.1.1 to all KiwiSDRs. Stock BeagleBone-Green/Black based Kiwis support one DRM channel, BeagleBone-AI Kiwis support four. Development work continues.”

Ironically, I had only recently published a post asking if anyone had ever attempted to decode DRM using a KiwiSDR. Turns out, several readers had by porting the IQ audio output into the DREAM application. Now that KiwiSDR will have a native DRM mode, this will no longer be necessary.

Many thanks, Mark, for sharing this tip! As you say, this is “mega news!”

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