FCC Proposes Authorizing Voluntary All-Digital AM Broadcasting!

Discussion in 'Amplitude Modulation' started by NA5B, Nov 25, 2019.

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  1. AG6QR

    AG6QR Premium Subscriber QRZ Page

    It's true that AM broadcast is primarily talk these days. That's because the audio fidelity on AM is so much worse than FM, so all the music got chased to the other broadcast band.

    But would that be true with digital? If digital AM combined the fidelity of FM with the range of AM, it could bring music back to MW. If its fidelity is so bad that it's only suitable for talk, what's the point?
    WA3VJB and KK4HPY like this.
  2. K5UJ

    K5UJ Ham Member QRZ Page

    The main point is to get through the RFI on the band, especially what's generated in new cars. FCC, instead of dealing with forcing manufacturers to make RFI quiet products (because that's bad for business) is using digital transmission as a band aid fix. Music has nothing to do with it.
  3. N2DTS

    N2DTS Ham Member QRZ Page

    Are you saying you want MORE government regulation?
  4. AC0OB

    AC0OB Subscriber QRZ Page

    The reason the fidelity of AM is not that of FM is because of the transmitted bandwidth. FM requires a 200 Khz occupied bandwidth and is allowed to transmit up to a 15kHz audio passband, which means for 100% modulation, the deviation is +, - 75 kHz.

    Historically, and in my view, had the AM industry not been so greedy about shoehorning in so many AM stations, and the FCC had allowed the same audio passband as FM, then AM today would have the same fidelity as FM and a much longer reach.

    "If you want to revitalize AM, increase transmitted Analog bandwidth to 30 kHz, Increase power to overcome the increased noise floor, thin the herd by getting rid of deadbeat stations with 24/7 Satellite feeds, and define a hard and fast receiver bandwidth standard."

    N1BCG, WA3VJB, K4KYV and 1 other person like this.
  5. WA3VJB

    WA3VJB Ham Member QRZ Page

    I agree with other on here who have pointed out it's the programming, not technical limitations, to blame for lost listenership on the "Standard Broadcast" band. Failed attempts should provide clues: AM Stereo, nighttime pissweak authorizations, pinched bandwidth, slack ownership rules, "translators" on FM, digital overlays on an AM signal, abandoned local mandates like news and community service. There's a parallel available with the Amateur Service, where nascent "digital" has been pushed as a savior of the hobby for recruitment and retention. Someone get back to me as to how that works out.
  6. AC0OB

    AC0OB Subscriber QRZ Page

    I was wondering about that as well and there is an article by Larry Todd in


    about this very thing.

    I don't agree with his proposing a different band for AM but the DRM+ technology is available.

    Most radio IC chipsets can decode DRM+ as well as Xpri's HD.

  7. K4KYV

    K4KYV Subscriber QRZ Page

    Here's the conflict of interest: broadcasters forced by the FCC to use a proprietary format (HD) that they must pay an annual subscription fee to use.
  8. N1BCG

    N1BCG Ham Member QRZ Page

    Having had to go through this with two AMs and two FMs, it was explained at the NAB convention years ago that HD was chosen because it would permit AM stations to continue transmitting their analog signal, albeit with limited bandwidth, while adding digital sidebands. Implementation on FM was simpler but required extremely linear transmitters. This would allow a transition period during which the digital sidebands would be gradually increased over time, eventually replacing the analog signal.

    By contrast, DRM is all or nothing, and broadcasters (here) were unwilling to give up nearly their entire audience as a means of encouraging digital receiver sales.

    The early demos were less than convincing and utilized unrefined codecs that sounded like low-bitrate internet streaming. Remember RealAudio? It was a surreal experience to remove the demo headphones and have the smiling sales rep ask "Pretty amazing, huh?" Yes it was, but not in the way he wanted. But, our company was all about being cutting edge, so...

    On the upside, I was told to "dispense with" the backup AM transmitters at the lowest cost possible and I had plenty of space at home for the rescue. The mains would become the backups and we'd be getting all new HD transmitters. Actually, the Harris FM transmitters received new HD-ready linear modules but the AM HD project was cancelled and so were my plans for Iron-Fest.

    Broadcasting with an 8 second delay (super-fun for live remotes) and the regular tweaking of the analog delay to improve blending in fringe areas made the HD experience memorable. The worst part? No one gave me a clear explanation why FM sounded bad or how having all those channels were going to compete with satellite. What it did do is divide up the advertising pie into tiny slivers.
    Last edited: Dec 2, 2019
  9. K4KYV

    K4KYV Subscriber QRZ Page

    I have yet to hear anything wrong with analogue FM on a good receiver connected to good speakers. I suspect any improvement via "HD" over regular FM would be inaudible to me or to most other listeners, even with the best receiver and audio chain. Most ordinary "consumer-grade" receivers these days are crap.

    Since the FCC has mandated the HD format for broadcasters, they should also mandate no annual subscription fees beyond the initial cost of the equipment.
  10. AC0OB

    AC0OB Subscriber QRZ Page

    I agree and that complaint has been brought up.

    The FCC's document FCC-CCIRC1911-05 states this all-digital format is a voluntary situation where no one is forced into using the MA3 digital mode, so you can stay analog AM and not be forced into it.

    But the equipment to transmit this digital signal is licensed by Xperi. Xperi bought DTS which had bought out Ibiquity's IBOC.

    The equipment and licensing costs are ridiculous:

    From the NPR FCC-CCIRC1911-05:

    "E. Conversion Costs and Receiver Availability
    33. Licensing and equipment costs. We tentatively conclude that the costs of conversion to all-digital, while variable by station, do not appear to be prohibitive and emphasize that such costs will be entirely voluntary. Commenters express concern regarding the cost of conversion given that the only all-digital system available to broadcasters is a proprietary, fee-based system.114 At present, Xperi charges a one-time licensing fee of around $10,000 for single main channel broadcasting and additional annual fees based on a percentage of revenues for each additional subchannel. We seek comment on the licensing costs of the HD Radio system and whether this fee presents an obstacle to the adoption of all-digital broadcasting. Are HD Radio license fees a disproportionate burden on smaller broadcasters, as argued by
    108 See proposed 47 CFR § 73.405 at Appendix B. We note that the Media Bureau previously issued a Public Notice seeking comment on the NRSC-5-A Standard. See Comment Sought on National Radio Systems Committee’s “In-Band/On-Channel Digital Radio Broadcasting Standard NRSC-5,” 20 FCC Rcd 10712 (MB, 2005). If we adopt the NRSC-5-D Standard in this proceeding, we propose to dismiss the 2005 Public Notice as moot. We seek comment on this.

    34. In addition to the HD Radio license, AM operators converting to all-digital broadcasting
    will have equipment and installation costs. The Commission has stated that it favors digital systems that
    do not require burdensome investments in new broadcast transmission equipment.116 AM stations that are
    already broadcasting in hybrid mode will need minimal equipment changes to convert to all-digital and
    thus will be able to do so at relatively little cost.117 Similarly, California and Missouri Broadcasters
    estimate that the cost for converting an analog AM station has fallen from $45,000 in 2002 to around
    $12,000 for current equipment.118 Xperi states that transmitter equipment sold by several manufacturers
    is compatible with the MA3 mode.119 We seek comment on the cost and availability of digital
    transmission equipment. Has the average cost of acquiring the equipment and licensing to convert to
    digital operation, in total, gone down in the years since adoption?

    35. In the case of WWFD, extensive upgrades, repairs, and modifications were necessary to
    prepare the station’s physical plant for digital operation.120 The WWFD modifications were carried out
    by a team of experts, including Kintronic and Cavell, Mertz, and Associates for the antenna system and
    Broadcast Electronics, Nautel, and GatesAir for the transmitters.121 Even so, ongoing transmitter issues
    “prevent the full benefits of MA3 transmission from being demonstrated at WWFD.”122 Specifically,
    even after considerable testing and upgrades, undiagnosed carrier-to-noise ratios impaired reception of the
    secondary and tertiary carriers.123 How likely is it that AM broadcasters, particularly early adopters, will
    encounter similar technical obstacles? What technical support will be available to converting AM
    broadcasters and/or their engineering consultants? Is extensive site rehabilitation likely to be necessary
    for other (particularly older) AM facilities? If so, what level of expertise and expense is likely to be
    required to duplicate the WWFD experiment? On the other hand, will some legacy AM antenna systems
    that are unable to pass digital carriers in the MA1 mode be capable of doing so using MA3?..."

    So we're talking at least $25k for a minimal upgrade, assuming of course your transmitter can already transmit digital. If not, then another $45k and up is in the picture.

    It seems to me that the only winners would be Xperi, Nautel, BE, and certain Broadcast engineers familiar with the technology and those are very few. I am familiar with the technology but none of my customer base is even remotely interested because of the IBUZZ fiasco.

    I pointed out in my comment to the FCC that while this 64-QAM technology is feasible, it lacks a lot of validation in terms of some of the problems noted in the testing, such as signal dropouts near power lines and bridges, interference protection, transmitter output power measurement, mask (bandwidth) compliance, etc.

    What bugs me is the fact that the NRSC has not tested the MA3 digital mode:

    "The NRSC has not tested or evaluated the MA3 mode, although all-digital operation is included in the NRSC-5 IBOC standard.20 The HD Radio digital technical operating parameters are set out in the NRSC-5 standard and in periodic publications issued by iBiquity/HD Radio (HD Radio Specifications).21" Page 4.

    I do not think that community AM stations with TPO's of 0.25 to 1 kW will sign on to this.

    Some of the larger corporate stations with TPO's of 5kW to 50 kW may do so.



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