Another thought on HD Radio

[jras20]

They need to start including HD Radio on shelf systems built in, WITH OUT extra cost to the customer. No one will buy a 200$ shelf system and then upgrade with another 200$. They also need to start making portable HD Radios for less than 50$. Lets get this going!

 

[Tom Wells]

They should be marketing HD portable radio/hand warmers for the football crowd right now!
What are they waiting for? A nice aluminum case with the main chip heatsinked into the case....
A cable to the 1 lb gel cell in a parka pocket

I find it silly to run a computer just to pick to pick up radio signals, especially given the outrageous inefficiency.

 

[pocket-radio]

Let’s not be to harsh. Radio executives, and I use that term loosely believe, in the digital era, HD is their future. They actually “think” in a time when people prefer to control their content, in ways that suites and mirrors their special uniqueness, and individual snowflake like tastes, that forced fed mass media programming that “sounds better” is the answers to their problems. They actually think that, and I guess that’s why you can hear the same thing on AM/FM as you can on HD. People love it so much, they just want something that “sounds better. ” it’s about the sound, never mind what’s playing or the fact that nobody is listening, or you can’t really pick up an HD station without a lot of trouble and hassles. I mean it’s possible, with a dish antenna mounted on the top of your car. Oh and another thing. Another radio study suggested, people seem to think satellite radio and HD are the same things. Can’t really tell the difference, I guess media over choice and lack of time strikes again.

 

[KB1OKL]

They need to start including HD Radio on shelf systems built in, WITH OUT extra cost to the customer. No one will buy a 200$ shelf system and then upgrade with another 200$. They also need to start making portable HD Radios for less than 50$. Lets get this going!

Upgrade? Upgrade to what? That's ibiquity speak, out here in the real world it's known as ruining your radio reception.

 

[jras20]

They actually think that, and I guess that’s why you can hear the same thing on AM/FM as you can on HD. People love it so much, they just want something that “sounds better. ” it’s about the sound, never mind what’s playing or the fact that nobody is listening, or you can’t really pick up an HD station without a lot of trouble and hassles. I mean it’s possible, with a dish antenna mounted on the top of your car. Oh and another thing. Another radio study suggested, people seem to think satellite radio and HD are the same things. Can’t really tell the difference, I guess media over choice and lack of time strikes again.

I don't believe that. I can pick up HD 84 miles with a dipole antenna and with Video to prove it. If you can't get the HD Signal than the signal isn't clear enough to listen to in the first place.

 

[KB1OKL]

FM reception is line of site as I'm sure you probably already know if you're a DXer, in other words your antenna has to "see" the transmitting antenna. I believe you probably live somewhere with a lot of flat ground like Texas or somewhere like that. HD doesn't go as far as analog because it is modulated at much lower levels simply because it is so wide, if it isn't it will severely interfere with adjacent stations like it already does on AM. Many of us live in hilly states like me here in Ma where it is completely useless unless you live very close to the transmitter. 84 miles is exceptional reception that most people will never achieve with an HD receiver with a dipole or even with a Yagi, 8.4 miles is more like it with a dipole in most locations especially moving in a car.

 

[Mike Walker]

First of all, HD isn't "modulated at much lower levels". The digital CARRIER levels (not modulation) are much lower.

Anyhow, I actually have never heard HD in a moving car. I get stationary reception with my roof antenna and rotor to 100+ miles, in a very hilly area (Wilkes County NC is at the foothills of some of the highest mountains east of the Mississippi). But an engineer friend of mine who works at a statioon in the Raleigh area says that in HIS car, HD stations from the Triangle (Raleigh/Durham/Chapel Hill...a much flatter part of the state) are good to 40 miles or so. Not bad considering the digital carriers are at 1 percent of analog power!

When the 10db increase comes, it'll eliminate the difference between analog and digital reception. And yes there will probably be some cost to pay for this in increased interference. There's a price for "pancaking" a new digital service onto the older analog one! With AM that price can be quite severe...so much so that it can actually (imho) result in a considerable loss of existing listeners...NOT COOL. On FM, however, the effects (to these ears) are VERY minor...something only a dxer (like me!) would notice.

 

[Play Freebird]

But an engineer friend of mine who works at a statioon in the Raleigh area says that in HIS car, HD stations from the Triangle (Raleigh/Durham/Chapel Hill...a much flatter part of the state) are good to 40 miles or so. Not bad considering the digital carriers are at 1 percent of analog power!

I'm familiar with most of those Triangle stations (I did a field strength survey about 15 years ago for someone who wanted to buy one) and they cover like the proverbial dew. The reason is that most are radiating 100 kW non-directional from very tall towers, and as you've mentioned, terrain in that part of NC is relatively flat. Results are similar in Houston, Dallas-Fort Worth, and some Florida markets.

However, the situation is much different in New England, New York, Pennsylvania, Baltimore-Washington, Chicago and suburbs, Southern California, and several other densely populated regions. Problem is, these are congested areas, so if stations turn up their digital sidebands by 10 dB, there's going to be some messy interference.

 

[Mike Walker]

A good point "Play Freebird". Even the most pro-HD person (and i'm pretty close to that on FM) would have to admit that at SOME POINT increasing the digital level WILL cause increased interference, and reduced coverage. So 10db can't be the universal "answer". For some stations it will be 3db. For others perhaps more than 10db could be made to work, in sparsely populated areas with few stations. It should be evaluated on a station-by-station basis.

And I'm STILL in favor of MANDATED inclusion of FMExtra on future digital radios. This would allow a completely separate path to digital for stations not wanting to dip a toe in the Ibiquity swamp, allow a far more cost-effective routo to digital for small stations, and allow big stations even more multicast options (or the ability to offer the same number of multicast channels at a higher bitrate, for better fidelity). Adding FMExtra would be very inexpensive, so why the hell not? And if somebody put Wi-Fi capability in the box, I'd sure as hell buy one! The best path to digital? ALL OF 'EM!

 

[calstymes]

Mike Walker thusly spaketh:

First of all, HD isn't "modulated at much lower levels". The digital CARRIER levels (not modulation) are much lower.

Correct! In AM, the total modulation level is expressed as amplitude power in the sidebands relative to the main carrier. In FM, the total modulation level is expressed as frequency deviation in the sidebands relative to the main carrier. In both of these systems, the digital HD carrier level provided to the total modulation level of the main carrier is considerably lower than that which the analog audio level provides. No doubt that is to what the original poster was referring, even if he did not say it quite correctly. No doubt the engineers who read this message board understood what he meant.

When the 10db increase comes, it'll eliminate the difference between analog and digital reception.

You're sure about that?

And yes there will probably be some cost to pay for this in increased interference. There's a price for "pancaking" a new digital service onto the older analog one!

You think?

With AM that price can be quite severe... so much so that it can actually (imho) result in a considerable loss of existing listeners... NOT COOL.

Not only is it not cool, but the AM system has already reached the point of providing diminishing returns as it is. Increasing the HD carrier power will likely be disastrous. It is not like the physics of this can't be predicted with a high degree of accuracy!

On FM, however, the effects (to these ears) are VERY minor... something only a dxer (like me!) would notice.

Do you think so? Or, do you think it is just possible that the point of diminishing returns provided in the FM system may be exceeded as well? Well, we won't really know until we try, eh? No doubt, the physics of this can be predicted with a high degree of accuracy too!

For answers to these and other burning questions, tune in tomorrow... same bat time, same bat channel.

To the FCC: PLEASE do your federally-mandated job and administrate what you are supposed to administrate and put an end to this madness, at least on the AM broadcast band!

 

[rbrucecarter5]

For some stations it will be 3db. For others perhaps more than 10db could be made to work, in sparsely populated areas with few stations. It should be evaluated on a station-by-station basis.

How is that any answer? In a moving car near the event horizon, the signal strength can swing by decades in fractions of seconds - the picket fence effect. How is a mere one decade of power increase, let alone 3 dB which is only double - going to change anything? Given the lock time required for HD decode, you will never notice a difference.

Inside of office buildings - the same thing. A couple of extra feet of penetration? Maybe 5? One more row of cubicles? Not a very significant increase in HD listeners, considering most people defy their computer departments and stream anyway. I can count half a dozen as I walk down the hall. There are probably hundreds streaming in this floor alone. Headphones or earbuds cost less than radios. do the math.

 

[Play Freebird]

In a moving car near the event horizon, the signal strength can swing by decades in fractions of seconds - the picket fence effect. How is a mere one decade of power increase, let alone 3 dB which is only double - going to change anything? Given the lock time required for HD decode, you will never notice a difference.

R Bruce, you speak the truth. Anyone who doubts this phenomenon should take a drive with a VHF field strength meter and observe the rapid fluctuations in signal level while the vehicle is moving. You'll see 10-20 dB swings even in flat, open terrain. Drive over a hill and the difference will be much greater.

FCC service contours don't really paint an accurate picture of coverage because they are statistically qualified; they represent the area where the specified field strength at 9 meters AGL is exceeded in 50 percent of the locations, 50 percent of the time, based on averages taken across the country. On top of a hill, the signal is usually stronger than at the base, so the top 50 percent of location are generally higher in elevation.

But remember -- population centers tend to favor valleys rather than mountaintops, so in rugged terrain, the field strength reaching most people is significantly lower. If the broadcast transmitter site has a clear shot into the valley, coverage usually will be acceptable, but if a desired community is on the back side of a hill, the signal there might be insufficient. On-channel digital boosters (aka "gap fillers") can solve this problem, but the IBOC system we've adopted doesn't easily accommodate them because they cause destructive interference to the host analog signal. However, under the BMC's 76-88 MHz expanded-band proposal, they could be added with little trouble.

Think of the building penetration problems these repeaters would solve in urban centers where the antenna farm is ten miles out of town. The cellular industry figured this out years ago -- why are the so-called "leaders" of the broadcast industry so obstinate?

 

[Mike Walker]

Cal asks "are you sure?" about my claim that the 10db increase will eliminate the difference between analog and FM coverage. Well, no I'm not of course. I am, howver, CONVINCED of it from the research I've read by CPB and others.

But there will be a "point of diminishing returns". There always is, especially when trying to pancake a new service onto an old one IN THE SAME FREAKIN' SPECTRUM! But these are the lemons we've been given. And after a couple of years listening to HD on FM, I'd say the lemonade THERE can taste pretty sweet.

 

[pqgeorge]

A good point "Play Freebird". Even the most pro-HD person (and i'm pretty close to that on FM) would have to admit that at SOME POINT increasing the digital level WILL cause increased interference, and reduced coverage. So 10db can't be the universal "answer". For some stations it will be 3db. For others perhaps more than 10db could be made to work, in sparsely populated areas with few stations. It should be evaluated on a station-by-station basis.

And I'm STILL in favor of MANDATED inclusion of FMExtra on future digital radios. This would allow a completely separate path to digital for stations not wanting to dip a toe in the Ibiquity swamp, allow a far more cost-effective routo to digital for small stations, and allow big stations even more multicast options (or the ability to offer the same number of multicast channels at a higher bitrate, for better fidelity). Adding FMExtra would be very inexpensive, so why the hell not? And if somebody put Wi-Fi capability in the box, I'd sure as hell buy one! The best path to digital? ALL OF 'EM!

Mike:
Much as I disagree with you about increasing the injection power for IBOC to 10 db. (which, IMHO, would be a disaster waiting to happen), I do agree with you that FMeXtra should be included in any digital radio made for the US market. There is no way that the "Ma and Pa" broadcasters (what's left of them) the non-NPR non-comm's including the grandfathered 10 watt (Class D) or 100 watt college stations or the LPFM's could afford to go with iBiquity. And even if they could, they would sacrifice a good amount of their analog coverage, never mind the very limited digital coverage they would have with IBOC.
I hope that FMeXtra will eventually become a mainstream technology for digital radio, allowing the smaller broadcasters to embrace it and give them the opportunity to expand with digital, including multi-casting and "surround sound" as well. FMeXtra can do that and much more. The cost, $15,000 with no "license fees per stream" at all (unlike iBiquity). You buy the FMeXtra server (with SCA encoder included), add processing and it's yours! Maybe it's time for Digital Radio Express to show what FMeXtra can do for the smaller operations of the world. Even the high-powered stations might embrace it too, instead of IBOC! One can only hope.

 

[Chuck]

I hope FMeXtra becomes mainstream too. I've tried it on our LPFM and translators. It worked quite well. We could actually afford it, and since the FCC seems to think it is OK to rebroadcast a secondary digital broadcast service (HD-2, for instance) on a translator, I think I could pay for the technology in a season of local sports coverage. It would make quite a few people in my area very happy.

The recent issue of Radio World has an article about a station in the Netherlands that is multicasting using FMeXtra. They mentioned that more consumer radios are on the way. That is good news. If just two or three receiver choices were available, I think the technology would gain traction in the US, especially among small broadcasters. Of course the guys who are running HD could use it too along with their Ibiquity system. I don't see much downside, if only there were radios.

 

[Mike Walker]

Didn't I read in Radio World that NPR's tests have shown that with the 10db increase, HD has just as much power to penetrate buildings as analog FM? Now you certainly have a point with FM in a moving car. I find multipath in a moving car so bothersome, that I greatly prefer the sound of mono AM to the multipath noise of analog FM stereo, and believe this is why AM to this day does so well in hilly/mountainous areas. It SOUNDS better in a moving car in these areas!

 

[rbrucecarter5]

Didn't I read in Radio World that NPR's tests have shown that with the 10db increase, HD has just as much power to penetrate buildings as analog FM? Now

I read that, too. There is a $30,000 expensive spectrum analyzer in our lab. It isn't specifically designed for broadcast use, but I hooked it to a whip antenna and took it out into the hall by the row of cubicle. I set it up to look at a local HD station - saw the recognizable shape of the whole channel with HD sidebands. Then I moved it to and from the window, setting a reference level near the window. Then I moved it away. Past an initial 20 feet or so where the signal held in, it started dropping 10 dB every 5 to 6 feet. 5 to 6 feet is about half a cubicle. So a 10 dB power increase won't do much of anything.

Hardly a controlled experiment I know - I wish that piece of gear had a decent export graphic file function, I could have posted it. But still - NPR's assertion that 10 dB more will penetrate buildings as much as analog FM - if I were a Mythbuster I would say: BUSTED!!!! The truth of the matter - analog hardly penetrates these buildings at all, so neither will HD. A little side experiment with a Sony SRF-A1 shows the same thing - FM really good right at the window, 20 feet away - OK, by the time you are 50 feet into the building - GONE. On a hot little DX unit that does really well on even rim shot signals right at the window.

Office workers are streaming. They can't get analog FM very far inside buildings, and they won't get HD no matter what the power.

 

[dumber than a box of hair]

Didn't I read in Radio World that NPR's tests have shown that with the 10db increase, HD has just as much power to penetrate buildings as analog FM?

Yes, you did, but as Robert Heinlein told us repeatedly, TANSTAAFL. According to the NPR Labs report that 10dB increase also brings with it destructive levels of interference to the analog signals, in some cases affecting up to 30% of the analog coverage area.

It is simply folly to believe that, given the way the FCC has (mis)managed the AM and FM bands over the years, you can cram more and more carriers at ever increasing levels into already overcrowded bands and not know that somewhere, somehow, something's gotta give. It may not be the case where you live and work, but given short-spacing on FM and skywave interference on AM in large areas of the country, trying to introduce HD carriers into bands not designed for them just isn't going to work without seriously damaging what's already there: the analog signals from which the radio business makes its money.

 

[Mike Walker]

rbrucecarter5, I would respectfully submit that you didn't prove that HD won't penetrate "as well as analog fm stereo". Instead, it seems to me that you proved it's penetration is just as poor as analog fm stereo. Not quite the same thing, but still you raise a valid point.

If the HD experience has taught us anything, it's that in the real world things often (usually, perhaps) don't work as lab experiments would suggest. After all, the current HD spec on FM was supposed to have been sufficient for comparable coverage/penetration. We know how that worked out.

Still, HD on FM IS receivable to great distances with the use of a decent antenna. In fact, in my experience, digital radio is far more reliable, and to greater distances, than DTV using the same antenna/rotor/preamp. Not a ringing endorsement to anyone in a rural area who, like me, has found DTV to be EXTREMELY lacking in coverage/penetration in comparison to analog. YES DTV looks and sounds FAR better than analog tv...WHEN IT WORKS. But it doesn't work a significant portion of the time (in my location, 40-60 miles from the closest DTV transmitters). HD on FM is rock-solid to far greater distances. Of course, with an indoor antenna that's not properly configured, both are pretty worthless.

 

[rbrucecarter5]

sounds FAR better than analog tv...WHEN IT WORKS. But it doesn't work a significant portion of the time (in my location, 40-60 miles from the closest DTV transmitters). HD on FM is rock-solid to far greater distances. Of course, with an indoor antenna that's not properly configured, both are pretty worthless.

One user is reporting 84 miles with a dipole on Houston stations. I've personally done 70 miles with a dipole on Dallas stations. How much freakin' coverage do the HD folks want? Even with the vast land areas covered by Houston and Dallas FM, by the time you are that far out, cows outnumber people per square mile.