Finally An Inexpensive Route To Digital Radio Listening

An inexorable trend over the last decade or more has been the exodus of AM radio stations from the low frequency and HF broadcast bands. The bandwidth and thus audio quality at these frequencies puts them at a disadvantage against FM and internet streamed services, and the long-distance advantage of HF has been reduced by easy online access to overseas content. The world has largely moved on from these early-20th-century technologies, leaving them ever more a niche service.

Happily for medium- and long-wave enthusiasts there is a solution to their decline, in the form of DRM, or Digital Radio Mondiale, a digital scheme that delivers cleaner audio and a range of other services in the same space as a standard-sized AM channel. DRM receivers are somewhat rare and usually not cheap though, so news of an Android app DRM receiver from Starwaves is very interesting indeed.

DRM uses a licensed encoding scheme from the Fraunhofer Institute, and this product follows on from a line of hardware DRM receivers that Starwave have developed using their technology. It uses the Android device as a front-end for any of a number of SDR receivers, including the popular RTL-SDR series. It supports the VHF variant of DRM, though we’re guessing that since the best chance of finding a DRM channel for experimentation is on HF that an RTL-SDR with the HF modification will be required. We think it’s an interesting development because the growth of DRM is a chicken-and-egg situation where there must be enough receivers in the wild for broadcasters to consider it viable.

29 thoughts on “Finally An Inexpensive Route To Digital Radio Listening

    1. Lots of common item in RF are, or patented, but patents expire and then everyone can eventually use.
      US2290159A Frequency modulation system (1940)
      US4680777A Quadrature-quadrature phase shift keying (1984)

    1. Digital Radio Mondiale predates the popularisation of Digital Rights management as a negative word. They’ve been trying to get it running since the early 2000’s.

  1. > and the long-distance advantage of HF has been reduced by easy online access to overseas content.

    But when a government doesn’t want their citizens to listen to a foreign online station all they need to do is implementing a filter or cutting a cable. A real transmitter in another country is impossible to turn off, and much harder to jam effectively for all population. Nostalgic memories aside, that’s a good reason why analog HF should be kept alive.

    Also, If I’m stranded on a desert island with some broken electronics around, with some luck I could put together a small analog transmitter using salvaged parts then key a SOS with a screwdriver, but if every station out there is looking for digital modes then I’m lost.

    1. I haven’t played with the recent drm software, but i know Dream could also demodulate AM.
      The typical transmitter used for DRM, can also be used for both.
      So i guess if needed, you could still revert if shortwave goee digital

    2. “impossible to turn off”
      suuure, keep telling that to yourself. Apart from physical destruction of the transmitter (be it overt or covert), a narrowband signal is easy to jam.

      1. I clearly meant transmitters outside of a country. HF allows propagation of radio signals from continents away, that’s why you can listen to distant shortwave (HF) stations during night but will never be able to do the same with a FM (VHF-UHF) radio station, no matter how powerful it is.
        Regarding jamming, if every “enemy” transmitter needs at least one (probably more if your country is wide) transmitter on the same frequency to be jammed effectively, a single cable cut, or 100 rules in a firewall, can easily cut 100 online radio stations, so my point stands.

        Just to be clear, I’m not against digital modes, I just don’t want the analog ones to go away.

    3. I believe this is one or more of the Ham radio frequencies.

      It is illegal to talk to some countries on ham radio unless their country agrees to it.

      There is also an undefined rule to avoid controversy on ham radio and most things we could say to a foreigner might violate the undefined rule. It is also illegal to have profanity on Ham radio as well.

  2. India is already using DRM Digital Medium Wave on a large scale. My favourite thing about DRM is Diveemo, where they can broadcast TV on Long, Medium and Short Wave. It has 144 lines resolution at 8 frames per second, and it looks surprisingly good on the 2 inch colour screen built into a digital radio. 📺

    1. With limited means, i’ve received shreds of India’s shortwave DRM transmission. The quality was atrocious – much worse than standard AM – because they used one DRM channel to transmit two mobile phone voice quality talk radio channels.
      The BBC had some programmes for a while, and those were standard quality. Not good, not terrible. Completely identical to 2000’s era internet streaming, with the heavy compression used.
      I’ve never managed to get it running properly. The often used ne602 mixers don’t seem to work as well as they should, or i’ve struck a batch of bad fakes.

  3. I don’t want restrictive codec licensing on a common shared resource. Imagine if someone enforced a patent in AM broadcasting.
    Keep the airwaves properly managed open and free

    1. Like that patent on Frequency Modulation in the 1940’s.
      The fantastic thing about patents, is that they expire. They do slow down innovation, as well as accelerate it in some ways, but it could be far worse. Imagine a world where patents lasted as long as copyright, the world would be mostly using 1920’s technology today.

      1. Patent holders are more likely to license than exclusive. There’s lots to be made if a patent holder can do it all by themselves. Even more if the burden can be spread around. e.g. ARM. Copyright that wouldn’t work so well.

  4. Maybe where you are, but in the U.S AM (530-1600khz) is alive and well. I struggle to think of a single transmitter that has gone off the air – someone will always buy them.

    It is true that these stations have moved a bit more “down market” (spanish language, religious, etc) but that’s not a bad thing since it allows more communities to be served.

    AM analog is effective technology. It can disseminate critical information to a large number of people with extremely minimal equipment. It should NEVER be turned off.

    1. yes and several are 50,000 watt stations tied to the US national emergency broadcast system in addition to normal daily programming. These cover large sections of several states and in to Canada during the day and Hundreds of miles further at night, so not likely to go away any time soon…

    2. The US AM broadcast band runs from 535 to 1705 kHz. Transmitter frequencies can be no closer than 5 kHz from the edge of the band, leaving 530 to 1700 kHz as usable frequencies.

      The number of AM stations have been declining for years. https://wirelessestimator.com/articles/2019/3511-broadcast-stations-added-in-the-past-decade-as-am-continues-its-decline/

      The FCC maintains a list of silent stations at https://www.fcc.gov/media/radio/silent-am-list

      The band should be repurposed. Analog TV went away, AM radio should as well.

  5. Digital radio versions for most radio stations is already available! The online services of all radio stations can be picked up generally on all Internet radio models. Stations output on the online services can also be bluetoothed and amplified on most sounds systems at home and in the car.

  6. I went to demonstrations of DRM at BBC short wave site (Rampisham) in mid 1990s. It has lots of use snd promises but the chicken and egg (receivers & transmitters) problem is huge. Pity as it works really well on medium wave, now there is better bandwidth.

  7. Well a big step is getting news out that it even exists. I didn’t know about DRM until like last week.

    Though personally I don’t see the need for digital radio, we got the internet already. I think terrestial radio is better off keeping analog, for simplicitys sake. Why change for changes sake? If AM needs better quality why not increase it’s frequency space, or is it that crowded in the US?

    Over here in scandinavia the MW band is empty, I know of a radiostation that wants to start up on the MW band but is not allowed, because of anti-analog sentiments in the regulator.

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