Will there come a time when broadcasters will give up on HD radio?

[fordranger797]

Just to caution all of you reading this, I am not a broadcast engineer, nor do I know anything about HD radio. However, i'd like to know more about how it works.

To start off, how exactly are these HD signals transmitted? Does it all go through the same frequency? Or is it all allocated like digital television is?

Secondly, is IBOC broadcasting wasting an unnecessary amount of bandwidth?

Third, do the HD signals react the same way digital television signals react? For example, I live in the Seattle area, where even traditional FM broadcasting can suffer due to topography.

Lastly, what is the future of HD radio?

Thanks for the info guys!

 

[MarioMania]

I hope soon

 

[okcradioguy!]

IBOC really should be classified IBAC. In both bands, AM and FM, the digital hybrid system employed actually rides adjacent to the host analog broadcast. In FM, it stays within the guard band of the FM channel with some pretty tight restrictions. Basically the next channel over up/down is the only one generally affected by the digital signal. AM IBOC isn't quite that nice. It slops crap several channels up and down from the main analog carrier. In fact, in many cases, it has a tendency to interfere with the host AM signal. Since AM signals travel quite a distance at night with more powerful stations, that adjacent channel(s) of crap interferes with other AM stations. In my opinion hybrid mode shouldn't even be allowed for the AM broadcast band. A full conversion someday to digital is the only thing that makes some sense, if there are enough radios that can pick it up. Here's the silver lining part of the program: Go to a Chevy or Ford dealership and check out what's in the new trucks and cars now. Yup! HD radio is quietly being stamped out of Detroit. While all of us were on here wailing that HD will never amount to a diddley-damn, low and behold Detroit decided they'd get around to installing it in cars. So here's what I see happening over the course of time. Those that invest NOW in building an audience with useful programming on HD2s are going to find those properties eventually gaining some ground. As more and more year models of new vehicles come out with HD, there will be a time that it will make some sense to go 100% digital, dumping the analog AM all-together. Many AM stations simply have very little audience left. Granted, some are doing fine, but most of them have power, and a lot of it to overcome the noise issues. I suspect there will be quite a few 100% digital AM stations in the next 10 years. I would like to see the FCC do some things to enhance that trend. One thing they could do that would help a lot is allow an analog and a 100% digital AM station to be counted as one in the market caps. That would encourage the big boys to "sacrifice" one of their lesser AM stations to offer both an analog and the digital only signal in a market. I would also like to see a new window opened for new digital-only AMs to simulcast existing analog AM stations, with a very, very strict requirement for the paired stations to remain simulcasted 100%. The X-band deal turned out be a huge joke. I wouldn't want to repeat that "fix".

 

[jhardis]

In FM, it stays within the guard band of the FM channel with some pretty tight restrictions.

What do you mean by "guard band?"

Standard FM is allowed a 75 kHz frequency deviation for modulation. So, in the simplest of viewpoints, a station at 101.1 MHz requires spectrum from 101.025 MHz to 101.175 MHz. It actually requires more than that since FM modulation generates essential harmonics. However, keeping it simple, the adjacent stations would require spectrum from 100.825 MHz – 100.975 MHz and 101.225 MHz – 101.375 MHz. So, by "guard bands" for the station at 101.1, I presume you mean 100.975 MHz – 101.025 MHz and 101.175 MHz – 101.225 MHz (each 50 kHz wide). Again, this is not wasted spectrum—it is essential to accommodate harmonics from the modulation.

Basic IBOC (that is, not "extended") requires spectrum from roughly 130 kHz to 200 kHz off carrier. So, for that station at 101.1 MHz, the IBOC signal can be found at 100.900 MHz – 100.970 MHz and 101.230 MHz – 101.300 MHz. These are not in the "guard bands." These are squarely in the core channels of the adjacent stations.

And as for "tight restrictions," prior to the IBOC era, the FCC required that off carrier power in this range be below 0.3% of the station's total power. With the introduction of IBOC, the FCC allowed a factor of 3 increase, to 1%. Since then, IBOC proponents have been fighting for yet another factor of 10 increase, to 10%.

- Jonathan

 

[iyiyi]

Broadcasters are not going to give up on HD radio. HD provides too many options and versatility for future growth that analog is incapable of doing.

The analog FM channel is 200kHz. Modulation is +/- 75kHz with 25kHz guard bands on each side. The FCC allows a slightly higher modulation swing if SCA subcarriers are added.

The digital HD signal does extend an extra 100kHz into each adjacent channel. This digital data has been known to "woosh" analog signals of the adjacent stations. This digital HD data does not adversely affect HD signals on adjacents, or vice versa, only analog signals are degraded.

-

 

[dougw9wi]

To start off, how exactly are these HD signals transmitted? Does it all go through the same frequency? Or is it all allocated like digital television is?

IBOC stands for "In Band On Channel". That means the digital signal is broadcast within the same 88-108 or 540-1700 band as the analog signal, and on the same channel within that band as the analog signal. (Digital TV might be considered an "IBDC" system -- digital TV is broadcast in the same frequency band as analog was, but on different channels)

Arguably, IBOC is not actually "on channel". Some of the digital sidebands "spill" outside the analog channel. Some of the analog signal also spills outside the channel; the FCC had limits for how much of this "spill" you could have in analog. The digital signal complies with these limits.

(on the other hand... the analog "spill" was relatively weak & infrequent. The digital "spill" is continuous and just weak enough to fall within the old analog limits. In other words, it does cause more interference than the analog spill did.)

Third, do the HD signals react the same way digital television signals react? For example, I live in the Seattle area, where even traditional FM broadcasting can suffer due to topography.

HD Radio uses a different modulation technology, one that is better suited to mobile reception and reception in rough terrain when compared to the technology used by digital TV. I don't have any firsthand experience.

Lastly, what is the future of HD radio?

The big problem with HD Radio, as I see it, is the transition from analog. Digital power has to be severely limited to prevent the digital signal from interfering with the analog. But the result of low digital power is poor digital coverage; many listeners who get a decent analog signal can't get the digital. And as long as they can't receive the digital signal they won't buy digital radios. Switching to all-digital mode allows a large increase in digital power and essentially the same coverage as analog. But since almost nobody has a digital receiver, switching to all-digital mode throws away your entire audience.

What I suspect will happen on AM... is that station groups with more than one AM station in the same market will convert one of the smaller AM stations to all-digital, and then use it to rebroadcast the signal of another larger AM station that continues to operate in analog. Once enough digital receivers are in place (maybe, "If" enough...) they convert the larger AM station & either shut down the small station or convert it to some other format.

On FM... I don't know that I see a path to full-digital. Due to an ill-advised (IMHO) FCC ruling, HD subchannels (only possible on FM) may be relayed in analog by FM translators. I think we'll find this to be the main application for HD FM: to allow station groups to establish inexpensive commercial LPFM stations over FM translators.

 

[davideduardo]

So here's what I see happening over the course of time. Those that invest NOW in building an audience with useful programming on HD2s are going to find those properties eventually gaining some ground. As more and more year models of new vehicles come out with HD, there will be a time that it will make some sense to go 100% digital, dumping the analog AM all-together. Many AM stations simply have very little audience left. Granted, some are doing fine, but most of them have power, and a lot of it to overcome the noise issues. I suspect there will be quite a few 100% digital AM stations in the next 10 years. I would like to see the FCC do some things to enhance that trend.

There are two problems with this analysis:

First, the average age of cars on the road in the US is now over 10 years. So it would take a decade for just half of the existing cars to be replaced with ones with HD assuming 100% of all vehicles had it installed as of today.

Second, in-car listening is about 1/3 of all radio listening. So replacing half of the car radios in a decade only changes potential listening for 1/6th of all measured listening. I see very little progress in converting "radios" outside of the car... in fact, those locations are becoming more and more based on listening on mobile devices where HD is irrelevant.

 

[spunker88]

On FM... I don't know that I see a path to full-digital. Due to an ill-advised (IMHO) FCC ruling, HD subchannels (only possible on FM) may be relayed in analog by FM translators. I think we'll find this to be the main application for HD FM: to allow station groups to establish inexpensive commercial LPFM stations over FM translators.

iBiquity probably wanted this to happen to increase the HD station count. How many of the stations using the HD LPFM loophole would drop HD if they were no longer allowed to do this?

 

[iyiyi]

iBiquity probably wanted this to happen to increase the HD station count. How many of the stations using the HD LPFM loophole would drop HD if they were no longer allowed to do this?

No. It is just one example of HD's versatility. Thanks to HD, WMVY radio listerers still have an OTA signal after WBUR threw them off of 92.7, for instance. Rhode Island Public Radio receives additional income by leasing their HD2 as a kicker.

-

 

[JaneChristo]

Will there come a time when broadcasters will give up on HD radio?

For FM radio? Never. It's here to stay....and will only get better

On AM Radio? Who knows! The future of AM (with or without HD) is seriously in doubt.

 

[KB1OKL]

Just to caution all of you reading this, I am not a broadcast engineer, nor do I know anything about HD radio. However, i'd like to know more about how it works.

To start off, how exactly are these HD signals transmitted? Does it all go through the same frequency? Or is it all allocated like digital television is?

Secondly, is IBOC broadcasting wasting an unnecessary amount of bandwidth?

Yes

Third, do the HD signals react the same way digital television signals react? For example, I live in the Seattle area, where even traditional FM broadcasting can suffer due to topography.

Yes but if your FM receiver does not receive the digital info it reverts back to analog unless you are talking a secondary channel then it comepletely drops out like digital TV, AM radio reverts back to analog except not in synch and the IBOC exciter causes a lousy pinched frequency response on AM.

Lastly, what is the future of HD radio?

It will probably limp along for a while longer and die a slow merciful death.

Thanks for the info guys!

message above

 

[stewie]

For FM radio? Never. It's here to stay....and will only get better

On AM Radio? Who knows! The future of AM (with or without HD) is seriously in doubt.

"Never" <- such an absolute word.

The more likely scenario? FM (HD or NOT) becomes what AM radio was to me growing up -> a place for my parents. Radio (FM, AM and HD) is becoming so far outpaced by mobile technology that using the term "never" is something I sure as heck wouldn't bet on.

 

[JaneChristo]

"Never" <- such an absolute word.

LOL! True...but does that mean we can never use the word never? ;-)

The more likely scenario? FM (HD or NOT) becomes what AM radio was to me growing up -> a place for my parents.

True...but the original question was:


Will there come a time when broadcasters will give up on HD radio?

FM Broadcasters are pretty much hooked on the ability to have numerous streams.....And FM broadcasters are not giving it up. They will more likely try to make the whole over0the-air digital experience better.

 

[KB1OKL]

They will give up on it slowly over a period of time, in fact they have been for a period of time now, after all how long can they continue to spend money on a system which most people doesn't even know exists and if they do know it exists don't listen to it? How long has it been in place, 6, 7 years now? It still doesn't work any better than the first day it was implemented and you can't get them in stores, on and on, it's dead, it just doesn't know enough to lie down. Strubie somehow connived the car makers to put it in some cars because after all how much more does it cost the car manufacturer, 2 more cents? Hey even they'll spend 2 cents on the very remote chance that it would be a success.

 

[dumber than a box of hair]

FM Broadcasters are pretty much hooked on the ability to have numerous streams...

Interesting choice of words..."hooked." Considering that the HD secondaries cost money to produce (even if it's just placing a computer in a closet somewhere, someone has to provide the programming), don't make any money and the vast majority of stations don't have HD at all, it makes one wonder what exactly it is they're "hooked" on.