IBOC rules published in Federal Register

[rbrucecarter5]

(1360) left their IBOC on "accidentially" at night and the range of the digital signal was restricted about the 50mv/m contour due to the analog signals coming in on 1350 and 1370.

This is a foreshadowing of things to come on the 14th. I am really glad I am not a station engineer who openly advocated this debacle. It is very likely there will be substantial coverage problems - not only for the digital signal, but also for the analog signal due to high levels of background noise from HD stations on adjacent frequencies. And when that happens and nighttime audiences decrease dramatically due to coverage problems - guess whose neck is going to be sticking out on the chopping block: the engineers who advocated this digital system! I would not want to be in their number. Prudent engineering practice would have dictated a lot more testing under real world conditions at night. It doesn't seem wise at this point to perform a nationwide experiment with a vital resouce: the nation's airwaves. Stations are supposed to operate in the public interest. ALL of the public, not just people within a protected contour. All the people includes impoverised rural listeners in the western 2/3rds of the nation.

 

[dumber than a box of hair]

guess whose neck is going to be sticking out on the chopping block: the engineers who advocated this digital system! I would not want to be in their number.

...which is probably why the marketing of HD Radio was aimed directly at management, and not engineering. It's perfect. If it works, management takes the credit...and if it kills the AM band, management can always blame the engineers for not telling them in advance.

 

[vsa]

No reason to get worked-up into a lather. The solution is already being planned. Key members of both houses of Congress are readying bills, with the advice of iBiquity and the NAB, that will amend the laws of physics. The only thing that's been holding it up is satcater efforts to attach a rider that would keep their birds up in the sky in perpetuity. The NAB is strongly opposed.

 

[Tom_Ray]

All we can do is HOPE THE LAWSUITS START POURING IN,IN WASH DC!!

And on what grounds? The FCC regulations, as published, are laws.

Tom Ray
WOR

 

[Tom_Ray]

HD radio will save the AM band you know.

If you're trying to put words in my mouth, it won't work. I have never made this statement.

Tom Ray
WOR

 

[Tom_Ray]

Tom, as you're well aware, NRSC mask compliance measurements are made with the spectrum analyzer in "peak-hold" mode for at least ten minutes. This amount of time is specified in the FCC rule (73.44) because it takes a while for analog sideband peaks to "accumulate", because they are of short duration and have a low average power.

Try changing the analyzer from peak-hold to averaging mode, then compare the occupied bandwidth of an NRSC-compliant analog-only station with one running HD. I would expect a big increase in energy on the first-adjacent channels and beyond, because the digital sidebands are continuous.

Shouldn't the averaging method do a better job of representing "real world" interference than the peak-hold method?

The NRSC measurements are made in averaging mode. As are the HD measurements. And yes, in averaging mode they fit under the present mask.

Tom Ray
WOR

 

[Tom_Ray]

We will see how your nighttime audience more than 10 miles away from the towers enjoys IBOC hash from WLW and WGN mixing with your analog audio. Because WLW and WGN analog signals will make digital decode very difficult except in the central part of the city. Have fun - I don't envy your future problems after September 15th.

They'll probably enjoy it just fine - because they won't hear any! I participated in the tests. We were 85 miles from the WOR antenna before there was any significant noise from WLW's HD. And that was to the side of the secondary lobe.

And the digital decoded just fine to the 80 mile point.

I already know what to expect from and to the WOR signal - I WILL be having fun - as I simply sit back. Nothing anyone hears will be worse than what Fidel shoots up the coast every night.

Tom Ray
WOR

Tom Ray
WOR

 

[Len14043]

[/quote]

They'll probably enjoy it just fine - because they won't hear any! I participated in the tests. We were 85 miles from the WOR antenna before there was any significant noise from WLW's HD. And that was to the side of the secondary lobe.

And the digital decoded just fine to the 80 mile point.

I already know what to expect from and to the WOR signal - I WILL be having fun - as I simply sit back. Nothing anyone hears will be worse than what Fidel shoots up the coast every night.

Tom Ray
WOR

Tom Ray
WOR

[/quote]

I applaud your station for being at the forefront of digital radio. However, I am skeptical that it will work for the majority of the AM stations. I live in Cincinnati and have decoded WLWs digital signal for nearly 200 miles north on I-71. The decoding was fine if you were on a highway away from powerlines and other sources of noise. Whenever I left I-71 and went into a small town, the digital signal would fail due to the powerlines, neon signs, televisions, etc. We had a severe thunderstorm and WLWs digital signal failed in downtown Cincinnatti which is about 30 miles from the tower (admittedly, the analog signal was nearly unlistenable due to the continuous crackling.) When you did your testing, did you remain on the highway or did you travel through towns where the noise level is generally higher? Please don't interpret my skepitcism as being anti-IBOC. I would love to see this technology succeed. I believe it works well for FM based upon my experience and works well for the more powerful AM stations during the day. I am just having a difficult time envisioning how the digital signals will be effective at night due to the increased noise brought about by the skip. After September 14, I hope my skepticism proves to be unfounded and your critics here are proven wrong. Good luck with your station.

 

[vsa]

HD radio will save the AM band you know.

If you're trying to put words in my mouth, it won't work. I have never made this statement.

Tom Ray
WOR

I wasn't quoting you, was I? Actually, the FCC has come pretty close to saying it. Let's go back to October 11, 2002.

http://fjallfoss.fcc.gov/edocs_public/attachmatch/FCC-02-286A1.doc

"...The number of active AM stations in the United States reached a peak of approximately 5000 in 1991 and has steadily declined since that time.  Currently, only about 4700 AM stations remain in operation, and these account for only 20 percent of estimated radio advertising revenues.  The record in this proceeding presents compelling evidence that AM IBOC—the only feasible, near-term digital technology option—has the potential to revitalize AM broadcasting and substantially enhance radio service for the listening public..."

Come September 14th, my only regret is that every single AM station on the dial will not be running iBiquity's "in-band-on-somebody-else's-channel" system at night.

 

[rbrucecarter5]

Come September 14th, my only regret is that every single AM station on the dial will not be running iBiquity's "in-band-on-somebody-else's-channel" system at night.

Let's just let it happen - put as many stations on the air in HD as possible, and see what happens.

If I am right, and the band is completely trashed - I won't be celebrating with "I told you so". I will be hoping a solution can be found. I still think a frequency reallocation with only part of the band used for digital with 30 kHz spacing and no protections outside the city of license is the answer.

And - if I am wrong, I will graciously accept the comments from the other side of the issue. But I've been at this DX'ing game for a number of decades, and know what a little noise in the skywave is capable of doing to the band.

 

[Len14043]

Come September 14th, my only regret is that every single AM station on the dial will not be running iBiquity's "in-band-on-somebody-else's-channel" system at night.

Let's just let it happen - put as many stations on the air in HD as possible, and see what happens.

If I am right, and the band is completely trashed - I won't be celebrating with "I told you so". I will be hoping a solution can be found. I still think a frequency reallocation with only part of the band used for digital with 30 kHz spacing and no protections outside the city of license is the answer.

And - if I am wrong, I will graciously accept the comments from the other side of the issue. But I've been at this DX'ing game for a number of decades, and know what a little noise in the skywave is capable of doing to the band.

I would love to see an all-digital test station on the AM band in every market. I believe it is the only viable method for the AM band.

 

[Boulder Engineer]

Here's a thought.

The 1600-1700 AM expanded band is a wasteland ;D

How about putting the suggested all-digital stations in that part of the AM dial?

It would create a compelling reason for a growing listeners to actually use that spectrum.

On the engineering side, it would make things so much easier as the stations in
that part of the band use omni directional broadband sticks.

In the event an existing AM station couldn't use IBOC for technical or interference reasons,
then give them a second all-digital channel to simulcast on up there in the electronic ghetto.

 

[Len14043]

Here's a thought.

The 1600-1700 AM expanded band is a wasteland ;D

How about putting the suggested all-digital stations in that part of the AM dial?

It would create a compelling reason for a growing listeners to actually use that spectrum.

On the engineering side, it would make things so much easier as the stations in
that part of the band use omni directional broadband sticks.

In the event an existing AM station couldn't use IBOC for technical or interference reasons,
then give them a second all-digital channel to simulcast on up there in the electronic ghetto.

That is a great idea and I think it's along the same lines as Bruce's suggestion. For instance, a station on a graveyard frequency may opt to simulcast an all-digital signal on the expanded band instead of the flea powered hybrid signal on the first ajacients. If that scheme became popular, and if the AM band is dying like some posters suggest, the all-digital band could perhaps be expanded down to 1500. I doubt that will happen though because it makes too much sense.

 

[Len14043]

Here is a link to a report on hybrid and all-digital testing in Cincinnati and Washington. The testing was done by Ibiquity and I realize they have a vested interest in its success, but at least you can get an idea on how both modes compare. I wish that station was still broadcasting in Cincinnati so I could do real life testing of my own.

http://www.nrscstandards.org/DRB/Non-NRSC reports/AM_All_Digital_Report.pdf

 

[K6JHU]

What I would like to see is a test of HD, DRM, and Eureka-147 to see which is best. If we are going to propose 'all digital' we might as well use the best system around.

 

[Chuck]

Here's a thought.

The 1600-1700 AM expanded band is a wasteland ;D

How about putting the suggested all-digital stations in that part of the AM dial?

It would create a compelling reason for a growing listeners to actually use that spectrum.

On the engineering side, it would make things so much easier as the stations in
that part of the band use omni directional broadband sticks.

In the event an existing AM station couldn't use IBOC for technical or interference reasons,
then give them a second all-digital channel to simulcast on up there in the electronic ghetto.

That makes entirely too much sense. We couldn't possibly do that.....

 

[Len14043]

What I would like to see is a test of HD, DRM, and Eureka-147 to see which is best. If we are going to propose 'all digital' we might as well use the best system around.

Agreed. Let the best system for AM prevail. For FM, I believe the best system is Ibiquity. While their hybrid system has some problems, it works reasonably well and has a path to the all-digital mode. Other systems for FM do not have a path to the all-digital mode-as far as I know.