FCC proposes allowing AM stations to go all-digital

(Source: Radio Insight)

The FCC approved today the adoption of a rulemaking allowing AM stations to transition to all-digital operation.

Hubbard Radio’s “The Gamut” 820 WWFD Frederick MD has been operating in all digital mode since July 16, 2018 in collaboration with HD Radio owner Xperi. The new rulemaking will allow AM stations to go all-digital and establish operating parameters for doing so.

The FCC today also is opening a comment period on the removal of the programming duplication rule adopted in 1992. The rule limits AM or FM stations from airing more than 25% of total hours in an average broadcast week of duplicative programming. The rule applies to commercial stations in the same service (AM or FM) with substantial contour overlap that are commonlyowned or subject to a time brokerage agreement.[…]

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22 thoughts on “FCC proposes allowing AM stations to go all-digital

  1. Mangosman

    You could say that HD radio in the all digital mode will do the same thing. WWFD is only 4.3 kW during the day and 430 W at night. A lot of this power is in the carrier which contains no information.
    DRM on similar frequencies in India is being transmitted on over 30 transmitters with the highest power of 300 kW. A friend of mine listened to a DRM radio factory fitted to a Hyundai I10 in an underground garage and there was no breakup.
    Remember that if you are in North America, no DRM transmissions are aimed at your continent.

    There has been no side by side comparisons between HDradio and DRM on the same frequency on the same transmitter in all digital mode set for the same bandwidth. I wonder why? If HD radio is supposed to be so good you would expect that they would want to prove it!

    In addition DRM in the presence of an emergency can wake the receiver, tune to the emergency broadcast, increase the volume to speak the warning, along with displaying on an screen a map of the location, recommended escapes along with indexed multi-lingual text instructions. The emergency warnings can be limited to the desired area. This is very useful when the population is asleep. HD radio cannot do this.
    The resolution of the images is half the number of pixels in each direction of that used on VGA monitors which have much bigger screens than that on infortainment systems in vehicles and radios. This is better than just icons on HD radio.

    1. Mangosman

      I should add that the HD digital signal power is 0.3 % of the carrier. The carrier as in AM contains no information. DRM contains no carrier to waste electricity. DRM has a few low powered pilot signals to enable the receiver to accurately tune itself and to adjust the RF gain. Hence the DRM signal will be more reliable than all digital HD radio which will also drop out. There is no analog to “blend” with!

  2. Darrell Hagan

    So imagine this – here I am in the wake of the apocalypse after perhaps a big natural disaster or a war. Recovery efforts are underway but slow and spotty. I’d like to see if any radio stations are left which (hopefully) are broadcasting needed information.

    I wonder around and find an old portable radio. Still has batteries and powers up. I turn it on and tune across the band, hearing nothing except on occasional loud buzz. Oh no! I just remembered! Digital AM! Crap. Now I need either a digital receiver or an SDR, computer, and appropriate software. I’m screwed until I find another way to get vital information.

    Reminds me of the DRM disaster. Nearly every DRM station which I’ve tuned into in the past has been far too unreliable in terms of solid decoding to listen to for very long. An analog AM station can fade very close to the noise floor and I can usually still understand enough of the content to make sense.

    Some things should be left alone. While I am generally in favor of and in fact embrace many new technologies, there are some places where the application really isn’t best.

    1. Laurence N.

      On that basis, one could complain about any change at all to radio. Why should we adopt FM stations? What if a disaster occurred, I found an AM-only radio, but the local station has switched to an FM transmitter. Why should we allow television to transmit? If disaster messages are sent over that but I only have a radio, I could be left out.
      I don’t think that’s a good enough argument against this change. The technical arguments elsewhere in this comments section are better points, but those are simply arguing about which digital standard we’re going to use. If we never allow anything to change because we fear that a relatively implausible scenario will arise at a convenient (or technically an inconvenient) time, then the old technology will die slowly rather than being improved. I am unsure about this specific suggestion, and I don’t currently count myself among its supporters, but I will need a better argument if you wish to convince me we should reject it.

  3. Peter L

    Wahh, wahh, wahh. Across every radio forum I visit there is nothing from the peanut gallery but whining about ALLOWING AM stations to punch the MA3 button on their HD Radio importer IF THEY WANT. It’s almost as if everyone on these forums believes that THEY are the target audience of advertisers that pay those radio stations to reach.

    I, for one, welcome our new HD Radio MA3 Overlords! Bring it on!

  4. Steve

    The cited article is incorrect. The FCC did not approve “the adoption of a rulemaking.” It approved the adoption of a PROPOSED rulemaking. It will accept comments for a period of time, and then it will make the rules.

    So, the title of this post might be “FCC proposes allowing AM stations to go all-digital.”

    You can tell the FCC what you think before the rules are made final. Mike S. above links the draft of the document that was approved Nov. 22. On the first page of that, at the bottom, are instructions for making comments. I think we don’t know yet what the comment deadline is, but if you do it in at least the next 30 days I think you should be fine. The sooner the better.

  5. Mangosman

    There are virtually no TV transmitters on TV channels 2 – 6. This gives more digital radio mondiale channels (which are half the width of an analog FM channel) to accommodate all AM and FM channels combined. IN addition there is a much greater data rate available for 3 channels of better sound, coloured slide shows, multipage text and an emergency warning system which will wake the radio say the message and show detailed text warnings with coloured maps.
    This system will also work in the AM band but has less data available. http://www.drm.org

  6. Mangosman

    This decision is in the same poor technical foresight that the FCC and industry have made for example;
    FM radio never reduced the amount of pre-emphasis from 75 to 50 micoseconds causing the a lack of loud high frequency sounds because of transmitter overloads from excessive high frequency boost prior to transmission.

    NTSC analog TV. Your country was the only one to need a hue control on receivers because the phase errors in transmissions could not be corrected hence particularly flesh colours could be any hue. The rest of the world went to PAL or to a lesser extent SECAM which does not have this problem

    ATSC digital TV is only used in North America and South Korea because it cannot handle reflected signals which are common in cities and inside houses using indoor antennas. The rest of the world went for DVB-T or the newer DVB-T2 or to a lesser extent the Japanese ISDB.

    HD radio even its all digital mode in the AM band still uses a wasteful carrier and the lower and the upper side frequencies are identical but with a phase reversal. This reduces the available data rate so is insufficient for good pictures or multipage text. It is also incapable of using the latest xHE-AAC compression which can produce good sounding speech at 12 kbit/s. Whilst MA3 is a 20 kHz wide signal which matches the allocation to analog only AM, the channel grid is in 10 kHz steps so adjacent channel interference will still occur. In analog audio they rely on less energy in higher audio frequencies, this is not the case for the digital data. Also the MA3 trial is low powered, no one has tried it at 50 kW!

    The rest of the world is using DAB+ or DRM. DAB+ is not possible in North America because their frequencies are used by VHF High Television.

    1. Mike S

      The mention of the old acronyms for analog TV standard brought back memories of the fun people had with these competing standards:

      NTSC = Never The Same Color
      PAL = Pretty Awful Looking
      SECAM = System Essentially Contrary to American Methods (there was another one, not in English, which basically translated to It’s Different Because We’re French)

      DAB+ was tried in Canada on the L-band and quickly abandoned. There was no market for it, in part because of the unavailability and high price of receiving equipment. But also, IBOC was gaining ground across the border….

      1. Mangosman

        PAL is not Pretty Awful Looking in fact is the best looking of them all. Living in a PAL country it stands for Peace At Last. No hue errors of NTSC and none of the coloured patterning in SECAM.

        Canada never used DAB+ it used the older DAB version which has poorer error correction and inefficient audio compression. Its major failing was that it was in L band which is 1.7 GHz which as you can see has a similar coverage area as a cell phone. They selected this band because the USA and Canada uses the DAB frequencies for TV and still do (channels 7 – 13). The other countries in Europe who used L band have now moved to 174 – 230 MHz band which has a much greater coverage area. In Australia DAB+ is radiated at 50 kW on high TV towers with a coverage radius of around 100 km (60 mi). Each DAB+ transmitter carries over 20 broadcast sound programs, with the exception of a couple of speech only programs all are in stereo at much higher data rates than HD2 – HD4 or the data rate used in MA3.
        Both DAB+ and DRM radios are selling better than HD radio receivers. The DAB+/DRM VHF low give more reliable reception when not power limited by interference to analog which is still a problem with MA3.

        Now due to impulse interference and in ATSC case poor directivity of antennas at VHF low TV broadcasters in North America have virtually vacated RF channels 2 – 6 leaving it free for digital radio. The cell phone industry are not interested in this band because the antenna will not fit in a phone and the available bandwidth is not enough. So it is available for DRM in this band if the NAB, FCC and CRTC can swallow their prides.

    1. Mangosman

      XPERI now hold the patents and are charging both broadcasters and receiver manufacturers licencing fees. This is on top of any patents for the actual hardware. They use their own digital compression which you will not see in the HD radio standard and is a tightly held secret. So you are unlikely to see any CODEC because the XPERI lawyers will be after them.

  7. Mike S

    Interesting. Just noticed that iBiquity’s main office was in Columbia MD, and WWFD serves Frederick MD.

    US sales of Sangean radios may pick up….

    1. Mangosman

      I have searched on many occasions to find actual numbers of HD receivers sold. xperi as was Ibiquity reluctant to publish the number of HD radios sold or in use.
      https://www.radioworld.com/industry/hd-radio-penetration-nears-50-in-new-car-sales These are new car sales so how long does the average car stay on the road? How many cars are sold each year?
      In 2015 there were only 17.5 million receivers mainly in vehicles in a population of over 300 million people isn’t a high penetration.

    1. Tom Servo

      No. Current HD-capable radios can decode this mode, and most of the station that will likely adopt this will also have some sort of FM simulcast partner, like a translator. So I don’t expect much real-world inconvenience from stations that do this.

      Personally, I’m all for it if it will help end the blight of “sidebands” that spill onto adjacent channels and cause interference after dark to distant stations. Everything I’ve read about WWFD’s test has been that it’s been successful, with few dropouts in the main coverage areas.

  8. Peter L

    I think it’s great, personally, even though I know that the industry will figure out a way to screw this up anyway.

    MA3 mode gives them stereo and text data (to match FM) but not the multi-stream ability that FM has. Still dealing with AM bandwidths, though MA3 is narrower than MA1.


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