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Analog Angle Blog

Is the End in Sight for Analog FM Radio?

It’s not news that AM broadcast radio is having a difficult time. With so many alternatives for real-time transmission of news, sports, music, and more via the Internet directly to PCs, handheld mobile devices, and cars, as well as availability of downloaded and stored playback, the need which AM fills is shrinking. Despite the upbeat statistics from the broadcasters which spin the sketchy data in the most positive way possible, the reality is that occasional and dedicated listenership has fallen, and most people seem to get their dose of AM, if any, as accidental background sound at the luncheonette.

AM is not the only broadcast medium which is struggling. The audience of its younger sibling FM is also shrinking for many of the same reasons. The drop has been less severe, since FM at least has the virtue of better quality audio due to its bandwidth and modulation technique, as well as much greater noise immunity (AM is inherently very susceptible to atmospheric and other noise sources).

The standard time-domain representation of amplitude versus frequency modulation does not show the tradeoff: FM is far more resistant to ubiquitous amplitude-induced noise sources, but at a cost of requiring more bandwidth for a given modulating signal

The standard time-domain representation of amplitude versus frequency modulation does not show the tradeoff: FM is far more resistant to ubiquitous amplitude-induced noise sources, but at a cost of requiring more bandwidth for a given modulating signal

However, standard FM – which uses analog frequency modulation of a carrier – may also be have limited days. According to a news report, Norway will be the first county to switch off all analog FM broadcasts by 2017 and replace them with digital audio broadcasting (DAB), sometimes called digital radio and high-definition radio. Other countries are considering similar moves.

In DAB, the analog audio is digitized, compressed using an MPEG algorithm, and then modulates the carrier using coded orthogonal frequency division multiplexing (COFDM). DAB was first deployed commercially in 1995 and is in widespread use in Europe, but has no coverage in the United States and just a little in Canada (see Digital Audio Broadcasting–Wikipedia ).

The advantages of DAB are that you can pack more channels into the spectrum, a precious and limited resource. According to the article, the Norwegian authorities claim “the DAB system in Norway already offers 22 national channels, compared to just five on the FM band, and has the capacity for 20 more.” In addition, the decoding algorithm used for DAB can accommodate fading and multipath, which conventional FM cannot do. The channel encoding can also provide information about what is being played (song title, artist, length, upcoming playlist) which users now expect from their music sources. Although the decoding process is more complex than analog FM, today's ICs and single-chip receivers make the difference negligible, while the benefits are substantial.

[Interestingly, key elements of both AM and FM broadcasting were developed largely by one man, Major E. H. Armstrong. After he invented the superregenerative receiver, he went on to invent the superheterodyne receiver architecture used which formed the basis for low-cost, mass-market five-tube AM radios. After that triumph, Armstrong conceived of and built the first FM transmitter and receiver (it had over 200 vacuum tubes!) to get around the inherent static and other noise susceptibility of AM. Although conventional expert wisdom said he was going the wrong way by using wideband FM, and that narrower bandwidth was the way to reduce channel input noise, he realized that you could trade off bandwidth for amplitude noise resistance, if you used a frequency-modulation scheme. ]

Are we going to miss FM radio itself? I don’t think so. But as FM and AM broadcasts fade away, literally as well as figuratively, it’s important to at least recognize what these two major modulation and demodulation techniques have done to spur wireless circuit design, component development, and system design (filters, for example). In fact, the modulation techniques themselves are disappearing, as they are the basis of almost all wireless and many wireless communication systems, whether analog or digital. Modulation is an analog process, even if the modulating signal is digital – that's physics, you can't get away from it.

What's your view on the potential disappearance of analog FM (and AM) broadcasts? Are you going to miss them, is it an “it's about time” situation, or is it a “don't care” scenario?

Related

AM Radio: The Beat Goes On (for a Little Bit Longer)

What Does Your Noise Nemesis Look Like?

13 comments on “Is the End in Sight for Analog FM Radio?

  1. eafpres
    May 18, 2015

    Hi Bill–I worry that once all RF transissions become digital, you need a more complex receiver.  When the aliens from another planet arrive to colonize the Earth, nobody will remember how to make a simple AM receiver to communicate halfway around the globe at night.  I think just like strategic reserves of fuel we should consider a “virtual stockpile” of simple technologies we can fall back on when the time comes.

  2. Bill_Jaffa
    May 18, 2015

    Maybe not for an alien invasion, but for many types of natural and unnatural disasters. A broadcast transmitter can reach everyone within the signal area, does not need any more infrastructure to reach N+1 listeners. And a basic AM radio is fairly easy to make, you could even go to a crystal version if desperate.

    The know-how to do all our modern technolgy rests on a very thin foundation, and keeping all that infrastructure working takes lots of visible and invisible skills, materials, and parts. It's the theme of many dystopian stories, for sure.

  3. Keith Sabine
    May 19, 2015

    Am radio I have not used probably since the 70's. Fading, interference and lack of bandwith all made it unsucessful. FM on the other hand offered a much higher quality of sound.

    The only problem I have with DAB is that DAB receivers take several seconds to boot up and get going. Apart from that, if they work well (and they do gice good quality sound) then I see no reason not to use them, as the available spectrum is getting more and more challenged.

    We've switched over from amalog TV in the UK to digital and in general there have been few problems; so why not radio too.

  4. eafpres
    May 19, 2015

    Hi Keith–the only time I use AM radio is in the car and then mainly on long trips where I may not get FM stations.  I had XM Radio in the car but dropped the subscription; I don't spend that much time in the car so it wasn't worth it.

    Here in the US things are moving to digital TV  In Colorado that happend over the last few years.  Some ruckus over people needing to get converter boxes but they were cheap and readily available so you don't even hear about it now.  Of course, I suspect cable has a much bigger market share than OTA TV now anyway.

  5. yannig_#1
    May 20, 2015

    I would be sad if FM will be replaced by DAB.

    several reasons :

    At present, FM quality satisfies me completely (for home listening). Different quality from CD, but very well suited for a “comfortable” listening (music or talking).

    If analog FM ends, I would have bought a new device. Device that will be necessarily very different from my tube tuner.

    And I'm probably not the only one in this case.

     

    A nice website : fmtunerinfo 

     

    Yannig

     

  6. Jean-Luc.Suchail
    May 20, 2015

    Analogue transmitters and receivers are simple and they can work in very poor propagation transmissions and at very long distances, not relying on any provider other than the transmitter. In digital, when propagations gets bad, you loose everything, in AM you can still get your favourite programme, with some loss in SNR or distortion.

    Luckily we, Ham Radions we will maintain AM (or rather SSB) and FM as we currently maintain CW…

    F1GFK

  7. Les Hammer
    May 20, 2015

    Unlike the switch to digital TV, which could be done with a cheap converter box installed by anybody, shutting off AM/FM radio would be expensive to replace in the car.  The hardware may be cheap, but getting it installed in your dashboard would not.  This would have to be done over a long period of time – with dual mode radios available and installed in every car now, and the phase out in 20 years when most of last years cars are not running any more.  Any “obsolete your car” in 5 years legislation will get a politician unelected fast.

  8. monle
    May 20, 2015

    Despite the fact that FM is over 50 years old, it sounds great on my Hi-Fi at home and in my car. It provides stereo quality and can carry traffic/music information data (RDS) as well.

    Immunity to environmental interference is more than adequate. I would even say that it is surprisingly good.

    AM is another story: much inferior sound quality, more interference and no stereo (at least in Europe).

    When we compare DAB with FM we will probably come to a similar conclusion as comparing MP3 against vinil records, that is: no real progress in terms of sound quality.

    And DAB receivers must rely on software that can be buggy and requires updates. I've seen this problem, but the device manufacturer was unwilling to fix it. We will have to get used to this.

    I'm also wondering if the digital radio protocol as we know it today will still exist in 20 years. Today's FM is backwards compatible with 50 year old radio receivers, because it's analog (no protocols!). I bet that the lifetime of DAB radios will not even come close to that of our FM counterparts, even if they are (at least in teory) software-upgradeable. But which manufacturer will take care of updating a radio that is anything more than 2 years old?

    In general, I'm in favor of progress; but in this particular case I'm somewhat reluctant.

  9. MWagner_MA
    May 20, 2015

    It seems the same arguments keep poping up in different areas.  Cable tries to tell us that its better to receive another 20channels when I might find only 5 of interest now.  In my car I listen to maybe 3 frequencies, and at times I shut it off because there is nothing worth listening to.  We don't need 20 digital broadcast stations as we don't have enough good content to fill it.  Analog FM is also very good in emergencies as it requires simple equipment (to receive) and is robust in handling some EMI, and its FREE (insuring anyone that wants to get the signal can).

  10. vbiancomano
    May 20, 2015

    AMEN!

  11. pswiatki2
    May 20, 2015

    I develop software for DAB receivers (for automotive industry) and have gathered some experience in the field over the years. Also on the broadcasting side (must interact with broadcasters to solve issues with the receiver when something unexpected happans – then the question becomes: whose fault it was). I can tell you – DAB has all those nifty features but I don't really think the listeners care that much. My favourite; Journaline – a hypertext service where one can read text and follow simple links embedded in it. Think of as a browser for text-only “Internet”, but the content must be received in full first to be usable. Not sure if that's true, but have been told one car company came up with the brilliant idea of embedding a speech synthesizer so that those “pages” can be read to the driver (voice recognition, in turn, takes care of navigating the links, I guess). 

    Then, they say the capacity (well, spectrum efficiency) is much bigger than FM.
    I wouldn't be so sure. They packed 10 services or so in my country and the audio quality
    isn't that high. One can surely pack much more than 10 – making audio quality definitely bad for most of those services crammed into the channel (single multiplex).

    So, that's what's going on in DAB. Some of the “insiders” play with it, but I am pretty sure the general public care less. Yeah, sure – DAB is said to become the only radio medium in Norway. Well, perhaps people there actually care, or they simply have no say (but can easily afford to change their radios). [much] Cheaper for the broadcaster to maintain DAB infrastructure there compared to current FM network – that's probably the major factor that drives this change. 

    Just my 2 cents.

  12. TomC123123
    May 21, 2015

    FM in North America will be around for a very long time.

    Some facts to keep in mind.

    1.  Europe (including Norway of course) has a very different Broadcast Structure than we have in North America. 

    2.  The DAB infrastructure in Europe has been defined and well established for well over a decade.

    3.  The quality of FM here far exceeds (in audio dynamic range and audio frequency response) the performance of our current digital music satellite broadcast systems.  With the ongoing mentality of fitting more channels per RF band, it does not appear that this will turn around.

    TomC

    Detroit, Michigan, USA

  13. sanjjay
    May 23, 2015

    may be

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