Full time HD has been affirmed by the FCC

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    I just got the word tonight that stations are now allowed to go full time HD and drop the analog on AM. I wonder how many will do it? Except for auto’s I don’t see a lot of HD radios around. I have two Sony’s myself.I had a 1500 foot Eastern Beverage that at times would lock on KSL 1160 SLC’s HD at night on the coast. But it took a lot uv to get it to lock.

    • This topic was modified 3 months ago by mwdxer1.
    • This topic was modified 1 month ago by Dan Packard. Reason: Changed topic head wording from "oked" to "affirmed"

    This is the first time this has made some kind of sense. Since some stations’ primary listening is to their translator, they have nothing to lose(audience wise)by converting their AMs to all digital and can greatly increase coverage, compared with a translator! Hybrid digital AM stations have been authorized to broadcast full time for several years.


    Apparently it is not in stone yet, but the AM band will be interesting if stations adopt it. Will they keep analog next to digital? I would think they would have to, like a 5 year window, much like the 3.0 TV deal. Who has HD radios, other cars?


    15 years ago when I was still doing a lot of MW DXing (or even listening to broadcast radio) and only had analogue equipment I’d have had a real problem with this.

    Now; yeah, whatever. It is what it is. So what.

    Betcha the news has Leonard spinning circles in his grave, though!


    It allows stations to broadcast a full digital signal with no analog component. They can continue in full analog or in the hybrid mode.


    Just because the FCC okays it, doesn’t mean the station will adopt it any way. Most CEs & GMs I know think there is no money in it.


    There still isn’t a ton of HD radios in cars, are there? I have to think there are next to zero HD radios in houses. How far off base am I?


    In 2018 52% of all new cars came with HD Radio.


    At present, 40 automotive brands are shipping vehicles in North America equipped with HD Radio technology—and more than 50 million HD Radio receivers are on the road, 18% of all cars on the road. The number of vehicle models featuring HD Radio either standard or optional in a feature package: 263; total vehicle models offering HD Radio as standard: 163 (62% of all HD-equipped vehicles). More than half (52%) of all new cars sold in 2018 came with factory-installed HD Radio receivers. And for fun: An HD Radio-equipped car is sold every three seconds in the U.S.


    I am going to ask a dumb question of the tech types here. If an AM was to go full digital, would it still be bound by the same patterns, power, nighttime power etc?

    If I had to make an uneducated guess (I have always been on the programming side) I would say the song would remain the same, as the carrier is still the same. Even if what it is carrying is different.

    Am I on the right path here, or not? What say you?

    • This reply was modified 3 months ago by Chico.
    Steve Naganuma

    Here is some more information.

    FCC Approves Digital AM


    I actually reside within the daytime contour of all-HD WWFD in Frederick, Maryland, The signal remains a novelty; I prefer to listen to “The Gamut” on WTOP-FM HD3 because of AM HD’s awful CODEC and the inability to handle skywave-groundwave collisions. During transitions between daytime and nighttime tbe signal becomes unstable, even at the higher 4300-watt level. Frequent dropouts occur as a result.

    Probably the most annoying feature is the 8-12 seconds required for signal lock-in. Powerlines, bridge overpasses or other RFI also can result in annoying dropouts, much more severe than analog AM. At night, WWFD AM 820 is just annoying digital hash on the dial.

    Perhaps the strangest artifact occurs when you drive close to the WWFD tower array off I-70. The familiar collision between direct-wave and groundwave near any AM station presents itself as a complete signal dropout, not the usual phase-collision we observe in an analog arrangement. Oh yes, did I tell you that younreally need to maintain tight phase tolerances in those directional AM arrays when running HD?

    HD on medium wave (AM band) is too-little, too-late. AM should have been repurposed as a high-power only service where skywave and extend groundwave coverage could have been exploited. Now it’s “AM RIP”… Thank you NAB, FCC, NARBA agreements, etc.

    As an aside, I do recoomend trying The Gamut for a bit… an ccletic mix of rock, folk, oldies, etc. The IDs contain a mix of translators, HD3s, and WWFD…

    • This reply was modified 3 months ago by chessyduck. Reason: Typos
    • This reply was modified 3 months ago by chessyduck.

    Andy Brown once characterized hybrid AM HD as “stuffing 10 pounds of shit into a 5 pound bag”, or words to that effect. If an AM station converts to pure HD, does the 5 lb. bag become larger? Will there be fewer artifacts and anomalies? Most of us have only experienced the hybrid version, which clearly isn’t ideal.

    KRVM-AM is in HD. If I just listen to it casually and not critically I can almost forget that it’s AM (no it’s not FM quality). The signal is less prone to dropouts than SiriusXM, which drops out constantly if anything at all interferes with the signal. That can be tall buildings, parking garages, heavy tree canopy over the road, or just weather. AM HD seems much less prone to dropping out than satellite. Will it be even better if it’s pure HD?


    The HD-only medium wave audio sounds like a good MP3 but does not compare in any way to FM analog stereo or (of course) HD FM. There are just too many coding artifacts although the-pure digital HD AM appears to have better separation than hybrid format.

    Wide-band analog AM experimented by WQXR was another solution but skywave also did not support that format. (BTW, at night WGY and WCBS occasionally kick into HD hybrid mode via skywave when conditions are just right. Our local HD WCAO 600 KHz does work at night but an HD outlet on 1400 fails miserably). WFED 100 kHz (ex-WTOP AM) dropped their HD hyvrid long ago…. the long coding delay would kill live sports play-by-play anyway,


    Hybrid AM is a horrible compromise and only works reasonably well under the best of conditions, such as a strong nondirectional signal. For instance, when KEX ran Christmas music, I found the experience fairly pleasant. Older recordings seemed to do pretty well, newer ones, not so much. I heard the full digital test of KRKO and was quite impressed. I thought it sounded just like FM, but without any noise and at over 200 miles away at night! There were no fades while I was listening. Their analog signal has never been listenable here to anyone other than a dxer and usually, not even then.

    Andy Brown

    “If an AM was to go full digital, would it still be bound by the same patterns, power, nighttime power etc?”

    Yes. Until such time as the dial is all digital which would allow for a reevaluation of spacing and interference rules, everything remains the same pending the actual text of the NPRM (Notice Of Proposed Rulemaking) that everyone is referring to, the fact sheet for which can be found here:


    I suggest anyone really interested in this topic read it. I just skim read it and here’s some of what I gleaned:

    Most of the spacing and interference rules are based on an analog carrier and its power distribution around center frequency. In the all digital mode, there is no analog carrier and the power distribution is different. There are lots of concerns about that in general and heavy doubt about operating that way at night when skywave interference enters into the equation. Also, there appears to be a side in the discussion that doesn’t want to do away with hybrid mode and also the lack of HD receivers penetration side.

    I would add to it that not every station is going to be “all digital ready” due to the narrowband qualities of directional antenna systems.

    I’ll go back and read some more when I have time. Right now I have to record my 3 hour radio show for next Monday.

    Please remember that this a NPRM which means they are soliciting more input from the public (meaning the manufacturers and the lobbies, not us). This means that there will be a cutoff date for comments, then the FCC will re-write the NPRM and put it out again for comments. This cycle can repeat 3 or 4 times before they actually have a proposal the FCC will vote on and a lot can change.

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