RW Article: AM Radio Must Go All Digital

[Carmine5]

Well, get those poison darts ready. Joe D'Angelo a veep at iBiquity has written an op ed on why AM must go all digital. While his article is obviously self-serving (or iBiquity-serving) he makes some good points. Tests show that digital AM provided a robust, clear signal farther and with less power than analog and that, in the long run, is more cost effective then running an analog plant.

Yes, it means making obsolete millions of radios but statistics show AM is already becoming obsolete in terms of listenership. So why not blow up the current AM scene and start fresh. D'Angelo did say that clock and table radios are becoming a thing of the past which may explain why we haven't seen hardly any new HD Radios in that form factor. But the automobile is digital AMs future.

I tend to agree with the premise that AM must go all digital. It's probably the best way to save the medium for a future generation not to mention that it could greatly improve AM station valuations. As it is many stations are either being given away or simply going dark.

The article is in the Sept. 25 edition of Radio World.

 

[frankberry]

Narrow band, high fidelity FM would provide better coverage and less adjacent channel interference.

 

[KeithE4]

Narrow band, high fidelity FM would provide better coverage and less adjacent channel interference.

Narrow-band, high-fidelity FM is physically impossible. And if any kind of narrowband FM were going to be tried on the medium-wave frequencies, it would have been done 60-70 years ago. There's a reason why they went to VHF for FM.

 

[KB1OKL]

Well, get those poison darts ready. Joe D'Angelo a veep at iBiquity has written an op ed on why AM must go all digital. While his article is obviously self-serving (or iBiquity-serving) he makes some good points.

At least this time we do not have to ask the writer if he works for ibiquity. I think the writer being a VP of ibiquity kind of negates his points, I have also heard that the all digital tests were not exactly a flaming success and that the signal was not so robust, this from DXers who ought to know. Also if a country like Britain legislates an all digital changeover date and it just ain't happening how would we expect a marginal at best system like HD to be a success over here?

 

[frankberry]

You are wrong. Sorry. I did it in the 90s with FCC approval. WQYK-AM. 50,000 watts.
If an FM station backed their modulation down by 30dB or so, that would be narrow band. The frequency response would not change.
Impulse noise is a problem but not as great as with amplitude modulation. Impulse noise doesn't make the audio disappear completely as it does with digital audio.

 

[kevtronics]

Narrowband FM on the AM band was tried decades ago as "Noise-Free Radio". It turned out to not be as "noise-free" as people had hoped, nor was it higher-fidelity than a good AM radio.

DSP-based receiver designs with impulse noise blanking come the closest to delivering "noise-free" AM radio. The factory radio in my 2007 Kia had impulse noise blanking on AM and it worked surprisingly well. The typical power line interference would make the audio sound a bit distorted but otherwise it was still clean and intelligible, with no audible buzzing. Only severe interference would render the audio unintelligible.

 

[frankberry]

Kevin,
I was the person who designed and operated the narrow band FM system for George Yazell.
The frequency response was far better than the AM component (and the station met the NRSC occupied bandwidth while transmitting AM and FM at the same time).
Eliminating amplitude modulation is required for any improvement.
The narrow band FM signal was multiplied and converted to wide band FM within the receiver.

 

[diymedia]

I have been expecting this sort of push for quite a while, and when the "AM Revitalization" NPRM comes out look for a well-organized campaign by HD backers to make the case for why all-digital AM-HD is necessary, backed up with the same rigorous testing that was done for prior developments.

But keep in mind that all-digital AM also sets a precedent: "If we can do it on one band, we should do it for the other." iBiquity et al. know the money's on the FM side, as is most of the qualitative functionality that the system has. If they can set regulatory precedent on AM (where it works least well) it positions regulatory inclination/momentum to eventually do the same for FM.

I sincerely hope those with common sense see D'Angelo's play for what it is: laying the groundwork for an eventual all-digital, mandated transition, using AM-HD as the stalking horse.

 

[TheBigA]

I sincerely hope those with common sense see D'Angelo's play for what it is: laying the groundwork for an eventual all-digital, mandated transition, using AM-HD as the stalking horse.

Honestly what do you expect him to say?

 

[diymedia]

Like I said, I expect him to say what he says. I will be *very* interested in the verbiage of the upcoming NPRM, as well as in the comments filed. The regulatory campaign to advance HD has played out three times already (adoption, "further rules," and FM-HD power increase) so the characters involved and roles they will play are well-understood. This time, I can watch the process unfold.

But for the sake of the band (and medium), I hope to be wrong.

For those who might not be RW subscribers, you can also read it online.

 

[kc1ih]

If radio goes all-digital it should be with a non-proprietary system. We can't have all radio be beholden to one company that can raise their licensing fees anytime they want.

 

[TheBigA]

The regulatory campaign to advance HD has played out three times already (adoption, "further rules," and FM-HD power increase)

And after all that, how many radio stations operate with IBOC? 200? Methinks doth protest too much.

The federal government is not going to mandate a monopoly. Regardless of the statements made by the monopolist. The industry is not united behind this technology. No one at the Radio Show was advocating it as a solution. And the FCC rep didn't mention it. I take that for what it is.

 

[Carmine5]

I have been expecting this sort of push for quite a while, and when the "AM Revitalization" NPRM comes out look for a well-organized campaign by HD backers to make the case for why all-digital AM-HD is necessary, backed up with the same rigorous testing that was done for prior developments.

But keep in mind that all-digital AM also sets a precedent: "If we can do it on one band, we should do it for the other." iBiquity et al. know the money's on the FM side, as is most of the qualitative functionality that the system has. If they can set regulatory precedent on AM (where it works least well) it positions regulatory inclination/momentum to eventually do the same for FM.

I sincerely hope those with common sense see D'Angelo's play for what it is: laying the groundwork for an eventual all-digital, mandated transition, using AM-HD as the stalking horse.

Of course, it isn't just D'Angelo of iBiquity. Ajit Pai, AM's new best bud, has been a proponent of digital AM as well. This may be what has emboldened Team iBiquity to push for it. As for a proprietary vs. non-proprietary system, bring up your concern to him in an email. I'm sure he'll listen.

There's been so much activity with FM recently; new translator CPs, an upcoming LPFM window, a proposed FM TX for AM stations window, that it may be years before the FCC even considers all digital FM. Besides, people seem to like FM as it is. But AM is on life support and the need for another new system of some kind seems warranted.

 

[diymedia]

And after all that, how many radio stations operate with IBOC? 200? Methinks doth protest too much.

The federal government is not going to mandate a monopoly. Regardless of the statements made by the monopolist. The industry is not united behind this technology. No one at the Radio Show was advocating it as a solution. And the FCC rep didn't mention it. I take that for what it is.

The industry's never been united behind this technology—the entire process has been one of struggle—and we've made it this far.

Still, I hope you're right.

I wonder if we, too, are beginning an eventual migration to FM?

 

[MickeyD]

Well this is a move that will kill the AM band. Force a deadline and watch the wave of licenses sent back to the FCC. If you are an AM station just getting by, where will you find the cash to replace your transmission system and/or studio equipment?

What would be different about AM content that is different than what is on today? High-fidelity crap. Sounds like more 3D TV.

 

[rbrucecarter5]

In what sort of fairy tale land do these HD proponents live? You want to kill the AM band? Just go digital and obsolete hundreds of millions of radios. People don't care enough about AM to replace those radios just to receive it.

The narrowband FM modulation scheme is interesting. For at least 20 years, wireless keyboards and mice have used it with +/-6 kHz 455 kHz ceramic filters, running at (formerly) CB frequencies because the glut of excess crystals were cheap once CB died. No reason the same architecture wouldn't work at AM frequencies, but I am concerned about bandwidth. Assuming enough bandwidth for FM modulation to work, a hybrid system of AM and FM modulation could maybe be worked out to allow existing AM radios to work while narrowband FM receivers slowly emerged in the marketplace.

 

[frankberry]

C-QUAM used narrow band FM for their L-R audio. MW FM receivers would be quite simple. Multiply the IF frequency so that the deviation is increased to 75kHz. Use a local oscillator to convert the multiplied IF frequency to 10.7MHz. At that point, it's wideband FM and can be treated as such within the receiver. For the FM signal to work well, the amplitude modulation would need to be reduced or eliminated completely.

 

[Tom Wells]

When I designed and ran a shortwave pirate transmitter in 1990-1991, I designed a certain amount of coupling between the
audio supply and the oscillator supply ( akin to poor regulation to the osc) that resulted in a combination of AM and narrowband FM
that sounded good on AM. I had no receiver with FM demodulation at the time, but had access to a frequency meter that showed
about 30 khz of deviation. There was a yearly pirate radio compendium being published in those days, and they noted that when
my signal was decoded in FM, it was just about if not the highest fidelity shortawave pirate that writer had ever heard.

It was a "bit" detrimental to the sound of the AM, but it still sounded very good with AM demodulation.
The main effect to AM demod was a sort of mild, fuzzy gating effect.

Wow, I just looked at the post and see what I dinosaur I am....I still hit the return key when I feel a line is long enough.
Any such formatting I add with the <return/enter> seems to have no effect, yet there's no good reason for why/where line
breaks occur in the displayed formatting of a post...hmmm....this is what I get for having learned to type on a mechanical
typewriter with real paper and still thinking in terms of doing the "format" live in real time.

 

[boombox4]

How many HD AM receivers are there in the average metro area today that are actually used on a daily basis? Maybe a couple hundred, if that? And they think HD will save AM? If that were going to happen, it would have done so already. People are not going to buy expensive, new AM receivers just to hear what they can already hear on a regular AM radio.

The only way I can see HD "working" is if the entire FM-AM broadcast spectrum goes totally digital, with the end user not being able to switch between AM or FM "bands". Just a bunch of HD radio channels, some happening to use frequencies between 540-1700 Khz, and the other channels happening to use frequencies between 88-108 Mhz.

 

[TheBigA]

The only way I can see HD "working" is if the entire FM-AM broadcast spectrum goes totally digital, with the end user not being able to switch between AM or FM "bands". Just a bunch of HD radio channels, some happening to use frequencies between 540-1700 Khz, and the other channels happening to use frequencies between 88-108 Mhz.

Even then, it wouldn't work. We still have a part of the population that is still not fully converted to digital TV. There would have to be a ten year conversion period, and even then, there'd be holdouts.

Just take these comments for what they are: The comments from a manufacturer who believes in his product. Period.