IBOC Interference

[KB1OKL]

These excerpts are from an article from several months ago in Radio World written by Dave Obergoenner. He's an engineer who has been involved in installing and maintaining IBOC equipment since the very beginning and still installs and maintains it. This man should be commended for standing up and speaking about what is most likely on the mind of the vast majority of technical people in radio today, he unreservedly opens up with his reservations about the looming power increase and about IBOC in general and he doesn't even mention the debacle that is AM IBOC since he only installs FM.

Some of his comments on the power increase:

"My observation is that anything greater than a 3 dB increase in IBOC power will not only cause problems for other broadcasters on first-adjacent and co-channel frequencies, but will also have a great potential for increased self-interference for stations."

"This will force listeners with HD Radios to lock them in analog mode, something some of the new radios are not even capable of, even if the clueless consumer would have any idea how to do it in the first place.

The radio has no idea that the IBOC carriers are not in any way connected with the analog station the consumer is trying to listen to. This is a basic, fundamental flaw in the HD Radio system that will cause all kinds of grief in the future if IBOC power levels are increased, and the radios are in greater circulation."

He also finds problems with the current power level:


"I’ve already personally measured stations using separate antennas, where the IBOC power is equal to, or even greater than the analog carriers in some locations. This causes a great deal of self-interference to the host station! Even the best radios cannot perform in these cases, so they just blast out loud noise bursts while traveling these parts of the coverage area."

"The other issue is interference to stations on first-adjacent frequencies ... 200 kHz away. There are already atmospheric conditions that cause frequent interference between first-adjacent stations from the IBOC carriers at the 1 percent power level, especially at this time of the year, as I write, when the "Sporadic E" is causing FM stations’ signals to travel a good deal farther than expected."

"I’ve already had situations where a local, non-IBOC station’s signal is quite listenable, but an HD Radio-equipped radio will be taken over by a co-channel (same frequency) station that is running HD Radio from a hundred miles away! "



More at:

http://www.rwonline.com/article.aspx?articleId=88744&mnu_id=14

 

[Play Freebird]

These excerpts are from an article from several months ago in Radio World written by Dave Obergoenner. He's an engineer who has been involved in installing and maintaining IBOC equipment since the very beginning and still installs and maintains it. This man should be commended for standing up and speaking about what is most likely on the mind of the vast majority of technical people in radio today, he unreservedly opens up with his reservations about the looming power increase and about IBOC in general and he doesn't even mention the debacle that is AM IBOC since he only installs FM.

If you dig out an old issue of Radio World from, say, 15 years ago, you'll see that Dave appeared as the "poster boy" in Harris ads for the CD Link and Digit FM exciter -- so he's certainly not an anti-digital "Luddite" -- and for that matter, neither am I.

Our problem is with the interference caused by the hybrid system -- and the fact that this harm is placed disproportionately on smaller, independent stations.

 

[HowardMBurgers]

These excerpts are from an article from several months ago in Radio World written by Dave Obergoenner. He's an engineer who has been involved in installing and maintaining IBOC equipment since the very beginning and still installs and maintains it. This man should be commended for standing up and speaking about what is most likely on the mind of the vast majority of technical people in radio today, he unreservedly opens up with his reservations about the looming power increase and about IBOC in general and he doesn't even mention the debacle that is AM IBOC since he only installs FM.

And I'll bet if you posted an article from some of the engineers at NPR who tested higher power levels already you'd get a different opinion. The difference is, you'd get actual data from the ones who tested it, not speculation. But you probably wouldn't post those comments or data would you?

 

[KB1OKL]

These excerpts are from an article from several months ago in Radio World written by Dave Obergoenner. He's an engineer who has been involved in installing and maintaining IBOC equipment since the very beginning and still installs and maintains it. This man should be commended for standing up and speaking about what is most likely on the mind of the vast majority of technical people in radio today, he unreservedly opens up with his reservations about the looming power increase and about IBOC in general and he doesn't even mention the debacle that is AM IBOC since he only installs FM.

And I'll bet if you posted an article from some of the engineers at NPR who tested higher power levels already you'd get a different opinion. The difference is, you'd get actual data from the ones who tested it, not speculation. But you probably wouldn't post those comments or data would you?

I think this article stands on it's own merit.

 

[OKCRadioGuy]

There is a broadcaster here that turned off their HD signals at 1 percent due to self jamming. They are using an ERI combined system in which they are injecting the HD into the "reject port" from what I understand. The other broadcaster still is running HD on their stations. I can take a spectrum analyzer and more the whip around and see the IBOC and analog levels NOT follow each other. This is allegedly coming out of the same antenna! I'd hate to see how a seperate antenna wouldn't work right. With all the big boys running out of money, maybe the insanity will slow down long enough for technology to fix the problem before we make more headaches for ourselves (we could only hope!).

 

[briankay]

It seems we can't go by NPR Labs conclusions on IBOC interference.

This document was just submitted (Jan 7th) to the FCC (.pdf 700 kB) http://fjallfoss.fcc.gov/ecfs/docume...?id=7020356180 that outlines flaws in NPR Labs' testing methodology regarding the IBOC power increase. The document provides evidence that NPR had a strong bias against a digital power increase and that they carefully omitted data, which in effect significantly skewed NPR Labs recommendations.

 

[audiophile.]

It seems we can't go by NPR Labs conclusions on IBOC interference.

This document was just submitted (Jan 7th) to the FCC (.pdf 700 kB) http://fjallfoss.fcc.gov/ecfs/docume...?id=7020356180 that outlines flaws in NPR Labs' testing methodology regarding the IBOC power increase. The document provides evidence that NPR had a strong bias against a digital power increase and that they carefully omitted data, which in effect significantly skewed NPR Labs recommendations.

Alan W. Jurison comments are borderline moronic. He's crying because digital signals are only getting out the 70 dBu in indoor enviroments.

Boo-hoo...put up an outdoor antenna. At least there is a easy fix for you, unlike the thousands of stations you'll be jamming if the blanket10x power increase goes through (including superpowered, grandfathered ones, as he suggested)...

 

[Savage]

Why would NPR have "a strong bias against a digital power increase?" That doesn't remotely make sense. It's also demonstrably false. NPR is on record with the Commission (touchingly holding hands with iBiquity and the Joint Parties) supporting the digital increase to -14 dBc or -10 dBc in cases where "no interference to adjacents" can be demonstrated. They even retroactively cobbled their own internet "interference calculator" to produce far more lenient results for digital increases (an ill-advised and ultimately self-defeating move, IMO.)

NPR is more open to the digital increase than I would be - especially considering that pubcasters are in the crosshairs more than are most commercial broadcasters in the IBOC interference department.

If anything, NPR should heed the age-old admonishment to "beware lest they get what they wish for." After all, when the gods are really angry with us, they answer our prayers.

 

[briankay]

Why would NPR have "a strong bias against a digital power increase?"

Because the reserved band typically has more speech and light audio processing and on the whole is a more crowded band in typical metro areas. The points Mr. Jurison makes about, indoor interference, using a single Kenwood receiver for all the tests, and the methods of MOS score calculation which don't stand up to scientific scrutiny, should be a concern whether you are pro or anti power increase.

 

[Savage]

For all the reasons you enumerate, Brian, I think it's self-defeating for pubcasters to be in favor of the increase. Screwing it up for analog in-car listeners (increased self-interference) is not a smart move. Neither will the increased adjacent-channel interference be a good thing for them.

They got their HD subs to program classical, jazz and other niche formats. NPR should have left "bad enough alone."

I think you and I agree on the overall impact and possibly disagree on the comment filed with the FCC.

 

[Carmine5]

When you consider that NPR Labs came up with the concept and engineering for side channels and that Public Radio has been at the forefront of station conversion then, yes, this accusation doesn't make sense. They definitely have skin in the game.

What we do know is that during the testing phase some fighting occurred between NPR engineers and those engineers handpicked by iBiquity, apparently, over methodology and NPR's inclination toward conservatism. This sounds like some residual blow back from that fight.

The whole power increase issue reminds me of a government pork barrel project (like the "bridge to nowhere") in which money, jobs and political survival are at stake, more so than the wisdom of such a project. With this -10 increase it seems as much an issue of invested money, job security, egos and survival of a company (or companies) as it is a matter of engineering or even the wisdom of such an increase.

 

[Savage]

Excellently and wisely stated, Carmine5. And your explanation succinctly sums up why the rest of the radio industry - outside of pubcasters and other Alliance members, that is - is highly skeptical about HD Radio.

Without the upside of fond hopes of stakeholders for an eventual payday from the licensure of HD - essentially taking the form of an annuity were HD to be universally adopted - there IS no real-world reason to adopt the system for broadcasters.

On its own "merits," so to speak, all HD represents are interference, more interference, expense, and maintenance headaches. It's a cheesy glitchy kludged transmitting system stuffed with proprietary technical roadblocks as iBiquity jealously guards its system, withholding vital data from the poor shlubs who have to make HD work in the field.....even from its licensed manufacturers. Take a casual stroll through any HD technical manual and note all the BOLDFACE PROPRIETARY WARNINGS and dire threats about disclosure or even photocopying.

Kind of makes you think of an electrified 10-foot high razor-wire fence - protecting a manure pile.

 

[Carmine5]

Without the upside of fond hopes of stakeholders for an eventual payday from the licensure of HD - essentially taking the form of an annuity were HD to be universally adopted - there IS no real-world reason to adopt the system for broadcasters.

Licenses and royalties, AKA, the Ibiquity annuity plan. That really sums it up.

Maybe they should put a counter on the company website-a running tally of how many HD Radios sold so far (like McDonald's hamburgers). Of course, that begs the question, can it be trusted.

c5