What if HD Radio's Sub-Channels Had a Secondary Carrier?

[RadioEngnr]

On the main HD1 if HD signal drops, Analog takes over, but if your listening to a sub channel, and it drops as many of you know, its gone... But as the subject states, what if the HD2's, HD3's could have a secondary carrier to fall back on if the HD signal drops, why not utilize the channels that DRE (Digital Radio Express) uses in the SCA, think of the money stations would save because they wouldn't have to up their power to get that HD signal out there, When I tested DRE many years ago that signal far surpassed my HD carrier DRE doesn't own the rights to those channels in the SCA band and for those who have satellite radio, in the larger markets Satellite radio is simulcast on the SCA of a radio station so if your in a parking garage or surrounded by large buildings you still can hear your 60's on 6, so why not HD radio?

I know iBiquity would not utilize this for one reason, and one reason only.... Analog Radio Has Got To Die

 

[JohnnyElectron]

I half agree with you; Radio eXtra SCA would be a great HD replacer or analog fallback, but I don't think it will 'fit' with HD-FM as-is and iBiquity would see to it to screw them over if they made progress.
If they could get it pefectly synchronized, even having an AM simulcast to fall-back to rather than no HD-FM2 might be an option?

Also, I believe both Sirius and XM have separate terrestrial repeaters that use their specific bandwidth (not FM or SCA) to duplicate one of the birds so that you could have a local backup for the holes where SatRad doesn't work so hot (underpasses), garages and tunnels. Even with a single local SatRad repeater, you still have LOS in 2 or 3 regular spots.
I'm surprised that SXM hasn't leased a channel or two for stations to use on an SCA or HD2/HD3 situation.

 

[RadioEngnr]

it was 12 years ago when I saw that repeater for satellite radio at a transmitter site, so your right my knowledge on that information is dated and it might have been feeding a separate antenna. and not the SCA of a FM, the box wasn't even rack mounted it was sitting on top of a table

 

[Chuck]

Even if it worked, I don't believe the FCC would allow it without a rule change. They have told me that because FMeXtra utilizes one or more SCA channels, it is a "private broadcast" and not allowed for public consumption. I think that is silly, but it is the rule as it stands. That's too bad, because I think it could have been a viable system.

 

[Ai4i]

I like the suggestion of having an AM fallback.
It would be sooo easy to program a radio such that when a sports or news/talk HD simulcast drops out, the radio would switch to the main AM station. In fact, I have thought about this very idea MANY times.

 

[dumber than a box of hair]

Even if it worked, I don't believe the FCC would allow it without a rule change.

Also, iBiquity would have to alter its own IP in order to permit it. Remember that every HD station pays licensing fees and in turn agrees to be bound by the EULA, which includes creating the digital spectrum to iBiquity's exact specifications. IOW, if it's not in iBiquity's specs, you can't do it.

 

[Kmagrill]

If the "secondary" carrier worked better than the HD2, and it was legal to receive as a public mode, why would you even need HD?

 

[Ai4i]

If the "secondary" carrier worked better than the HD2, and it was legal to receive as a public mode, why would you even need HD?

Audio quality including an infinite s/n ratio, plus building penetration.

 

[Tom Wells]

A great idea, but requires mapping to the proposed "other wavelength" carrier.
AND a synchronised, "fixed" displacement between the originating (analog) signal versus the digital, presumably
at a much higher frequency, where data redundancy is easier to ensure.

A fixed, defined offset would mean that a radio would ALWAYS know where to tune for the accompanying digital feed.


Which is what should have been defined for digital braodcast in the first place.

If that had happened, a major portion of the complaints about HD ibiquity iboc would never have been an issue.

If only RF engineers had been a major force in the development of HD...
Or if those who were, had been able to convince the ibquity upper execs that in an "in-channel" solution was
essentially self-defeating.

 

[dumber than a box of hair]

Audio quality including an infinite s/n ratio, plus building penetration.

And still the crazy notion that the quality difference between FM analog and HD is noticeable to most people refuses to die.

 

[Dr. Bob]

Audio quality including an infinite s/n ratio, plus building penetration.

And still the crazy notion that the quality difference between FM analog and HD is noticeable to most people refuses to die.

Because of two words, multipath and pre-emphasis.

 

[dumber than a box of hair]

Audio quality including an infinite s/n ratio, plus building penetration.

And still the crazy notion that the quality difference between FM analog and HD is noticeable to most people refuses to die.

Because of two words, multipath and pre-emphasis.

And still the still crazier notion that most people know or care what multipath or pre-emphasis are refuses to die.

If multipath is an issue with the analog signal, it will cause drops back to analog with the HD signal...and more than likely the listener is gone anyhow.

Look, we can sit here and argue all the technical jargon, sales figures and lies from iBiquity we want to, but the end result is: The public neither knows nor cares about HD radio. It's just not that much better than analog. It clearly isn't resonating with enough listeners to make a difference. And after more than ten years of trying six ways from Sunday to get it out there, it's time to stick a fork in it. Throwing more money and time at it isn't going to magically change it into a must-have. It's dead. Its promoters just don't know when to quit.

 

[Ai4i]

Audio quality including an infinite s/n ratio, plus building penetration.

And still the crazy notion that the quality difference between FM analog and HD is noticeable to most people refuses to die.

We were talking about using an AM station for fallback

 

[Kmagrill]

Audio quality including an infinite s/n ratio, plus building penetration.

And still the crazy notion that the quality difference between FM analog and HD is noticeable to most people refuses to die.

Because of two words, multipath and pre-emphasis.

And still the still crazier notion that most people know or care what multipath or pre-emphasis are refuses to die.

If multipath is an issue with the analog signal, it will cause drops back to analog with the HD signal...and more than likely the listener is gone anyhow.

Look, we can sit here and argue all the technical jargon, sales figures and lies from iBiquity we want to, but the end result is: The public neither knows nor cares about HD radio. It's just not that much better than analog. It clearly isn't resonating with enough listeners to make a difference. And after more than ten years of trying six ways from Sunday to get it out there, it's time to stick a fork in it. Throwing more money and time at it isn't going to magically change it into a must-have. It's dead. Its promoters just don't know when to quit.

Other than a few engineers, I've never heard any general listener complain of pre-emphasis screwing up the highs. Having listened to lightly processed FM in the studio and A/B switching between on-air and program buss, it's pretty hard to tell any difference at all, except the processed audio is slightly fuller sounding. Multipath may be a problem in some places, but even in locations like San Francisco and Portland, there are large areas of clear reception. Most towns aren't nearly as problematic and, even if they were, HD is also affected by multipath, as has been pointed out already.

In FM HD vs analog, the quality is not an issue that's going to attract listeners. Most cannot tell the difference and of those that can, many prefer analog to the compression artifacts of HD. If you listen to the spots promoting HD, it's clear that they know quality is not the seller, it's the multicasting. The only thing going for HD is multicasting. Surround sound could, eventually also be a technical bonus, but not yet. So, if HD is to gain ground, stations are going to have to put some effort into the HD2 and 3 streams without expecting much of a reward for quite some time.

Incidently, someone earlier lamented that it's too bad a radio engineer wasn't involved in the concept of HD. In fact, quite a few were. Lucent (Bell Labs) was one of the originators of what is now the Ibiquity system. The fact that there may be some technological ideas today that might have been less evident in 1993, doesn't mean that some smart guys weren't working on the system.

 

[dumber than a box of hair]

We were talking about using an AM station for fallback

Oh, great. Like that'll work.

"Excuse me, Mr. Repair Person. Why does my car's radio keep switching to muddy sound all by itself when I don't even change the station or adjust anything? I paid good money for this, and I expect it to work correctly. If you can't fix it I want the radio changed or my money back." And guess what? They CAN'T fix it.

Let's keep laser-beam-focused on the big picture. Having to continually chase our tails pursuing all the "fixes" (that aren't really fixes) for this horrible piece of technology just isn't going to cut it. Please, SOMEONE, put it out of our misery.

 

[DaveBayArea]

Because of two words, multipath and pre-emphasis.

Indeed, those are the two advantages major advantages. There are definitely situations where the HD signal is able to decode in strong-signal high-multipath conditions. Also, the lack of fancy processing for the highs can be advantageous. The downside is that most stations exhibit some weird artifacts in place of the multipath noise. I understand Day Sequerra has something called a Neural Audio Processor that fixes a lot of this, but I have yet to hear one with a 48 KHz HD broadcast.

The downside for our station is that the few places where HD provides a clear advantage is overwhelmingly negated by the problems it causes with adjacent-channel interference.

Dave B.

 

[rbrucecarter5]

The only thing going for HD is multicasting.

Incidently, someone earlier lamented that it's too bad a radio engineer wasn't involved in the concept of HD. In fact, quite a few were. Lucent (Bell Labs) was one of the originators of what is now the Ibiquity system. The fact that there may be some technological ideas today that might have been less evident in 1993, doesn't mean that some smart guys weren't working on the system.

That is also its biggest issue. If you are only listening to a station's HD-2 or higher channel, when multipath or other reception issues cause it to drop, you get dead silence. that is much more annoying than having the sound go back and forth from muddy to good.

They may have had some smart engineers working on the system, but even smart engineers can make mistakes. Like locating the sideband outside the channel, just so they could preserver RDS, SCA, and a few other services. All of these functions are duplicated by HD, and HD can do them better. If they had placed the HD subchannels inside the bandwith of the station, not only would there be no complaints about adjacent channel interference, but the gain / bandwidth product would help HD range much more than any plan to boost sideband power.

So - yeah - the engineers screwed up by:

(1) not realizing the fundamentals of the gain / bandwidth product
(2) underestimating the number of first adjacent reception scenarios across the country
(3) outright lying about the nature of AM receivers presently sold (ALL new AM radios are inherently broadband)
(4) not realizing an HD-2 dropout would be so annoying
(5) attempting to cover up defects in the system by silencing and insulting all critics
(6) not testing enough to uncover the defects in the system
(7) not building in fall back plans like C-Quam for AM and narrowing the channel for HD FM in case there were insurmountable problems

And I can think of lots more. Respect for engineers does not come solely from years on the job, job title, degree received, or who they are. It comes from the number of successful designs completed. And HD is a huge black mark on the resumes of all involved in its engineering. Lets call it exactly what it is - an engineering disaster.

 

[Ai4i]

(5) attempting to cover up defects in the system by silencing and insulting all critics

Should not have been burried in the middle of the list.

 

[Dr. Bob]

Audio quality including an infinite s/n ratio, plus building penetration.

And still the crazy notion that the quality difference between FM analog and HD is noticeable to most people refuses to die.

Because of two words, multipath and pre-emphasis.

And still the still crazier notion that most people know or care what multipath or pre-emphasis are refuses to die.

If multipath is an issue with the analog signal, it will cause drops back to analog with the HD signal...and more than likely the listener is gone anyhow.

Look, we can sit here and argue all the technical jargon, sales figures and lies from iBiquity we want to, but the end result is: The public neither knows nor cares about HD radio. It's just not that much better than analog. It clearly isn't resonating with enough listeners to make a difference. And after more than ten years of trying six ways from Sunday to get it out there, it's time to stick a fork in it. Throwing more money and time at it isn't going to magically change it into a must-have. It's dead. Its promoters just don't know when to quit.

You are correct that people don't care what multipath or pre-emphasis, they care about content and the experience. Using your logic, FM wouldn't have happened because, hey, it wasn't that much better than AM (and it took decades for it to be widely accepted), and FM stereo would not have happened because there's a big noise penalty over mono and most people won't notice or care. I have heard and continue to hear from listeners that get an auto with and HD radio and lament when they must switch cars back to a standard radio; some miss the sub-channels but many comment about the "clarity" of HD verses the analog FM.

I'm smart enough to know I won't change your mind (and most others on this board) but if, as you say, the system is dead, why are more automakers including it in their vehicles? Do you think they all have been "hoodwinked" by iBiquity? You are entitled to you own opinion but not your own facts.

 

[Dr. Bob]

Maybe some non-coms or commercial FM stations in very small markets are lightly processed but most commercial stations in markets of any size are at least moderately processed (I'm being very generous) so pre-emphasis is a consideration; more so that it used to be when the source material was vinyl. As I said in my other post, it ain't just me; I hear from listeners that have to switch back from HD to analog and complain about the "clarity" of the analog FM.