"I-Buzz"

[VeteranPD]

The problem lies with the crappy am radios that have proliferated the marketplace for years and are probably worse than ever today.. On IBOC AM the digital signal should be down about 60 dB, as I recall, at second adjacent. Sadly, am radios lack the rejection needed. You need to beat up on the radio manufacturers not IBOC stations. Long Island's am 740 in Huntington has been ranting about the alleged splash from WOR and WABC. However, if you look at the spectrum analyzer, you'll see that both WOR and WABC have the required second adjacent attenuation which should make 740 listenable in it's primary coverage area.
My gripe with IBOC is that the signals are fragile and difficult to lock in. I suspect part of the problem is that the digital power is a small fraction on the analog power. Until it's "plug n' play good" market acceptance will be difficult. IMHO HD AM sounds pretty darn good when you can latch onto it. I listened to WOR's HD Saturday in the middle of a big thunderstorm. The bolts of volts were flying all over the neighborhood and not a crackle was heard on the HD signal.
I would love to hear a music intensive AM like Canada's CHOW (also 740) in HD.

 

[davideduardo]

All the locations mentioned in the above "Link to the full story" are within WPHT's 1210 AM (class A - old class 1a) 50 kw non-directional primary fulltime contour.

The USABLE contour of any AM is about 20% inside the innermost radio-locator red curve. Essentially, no listening talkes place outside that area, as shown by Arbitron diary returns.

Radio-locator is clearly labeled as "for entertainment purposes only" and the contours in many cases do not take into account all the variables of coverage, and the outer curves are vastly exaggerated.

The "local", "distant" and "fringe" lines on the AM maps corresponds to the predicted 2.5, 0.5, and 0.15 mV/m contours respectively (of the horizontal groundwave propogation only).

An in a metro, 10 mv/m is about the minimum for any listening to take place due to manmade noise, atmospherics, etc.

 

[Mike Walker]

They're not "vastly exaggerated" (radio reception contours) for radio nerds like me with 200' longwire antennas in the back yard. All 15 of us

It seems to me that a big problem with AM HD is that it uses the same "RF Mask" created for analog AM. The problem is, this mask was for analog audio, transient in nature, rather than a continuous digital stream, which is "always-on". It's one thing for a cymbal crash (or other transient, high frequency event) to "splatter" onto an adjacent channel for a fraction of a second...quite another for that same level to be present ALL THE TIME.

 

[PhilGalasso]

Sadly (or not, depending on your perspective) the days of very long distance AM reception are coming to a close.

Of course, the biggest threat posed by nighttime IBOC transmission is actually to LOCAL AM reception. Nighttime skywave will propagate the IBOC digital sidebands of distant stations as it propagates the analog component. If a strong IBOC station, propagated via nighttime skywave, is on your first adjacent, it will cause a very annoying hiss on your local station. For example, WTWP, a 50 kW station on 1500 kHz can be expected to totally trash local stations on 1490 and 1510 when they light up their IBOC at night. The AM band will probably end up sounding like the high end of the 40 meter ham band during the Cold War, when Russian white noise jammers jammed numerous Western shortwave broadcast stations operating on that band outside of the Americas. I am already hearing IBOC hiss during the day on stations operating on second adjacent channels with respect to IBOC stations.

The Europeans got it right with DRM. They are using it on both mediumwave (AM) and shortwave and those digital signals propagate quite well over long distances. The disadvantage to both IBOC and DRM is the expense of the receivers.

IBOC is a high-performance automobile equipped with square wheels and a rag stuffed into the carburetor. Those who designed the AM version should be garrotted!

 

[Mike Walker]

But K2PG, in urban areas of the US, there's something on nearly every frequency across the AM dial. NOT SO IN EUROPE. They have ROOM on the MW (AM) band for DRM. We don't.

 

[R.F. Burns]

Sadly (or not, depending on your perspective) the days of very long distance AM reception are coming to a close.

Of course, the biggest threat posed by nighttime IBOC transmission is actually to LOCAL AM reception. Nighttime skywave will propagate the IBOC digital sidebands of distant stations as it propagates the analog component. If a strong IBOC station, propagated via nighttime skywave, is on your first adjacent, it will cause a very annoying hiss on your local station. For example, WTWP, a 50 kW station on 1500 kHz can be expected to totally trash local stations on 1490 and 1510 when they light up their IBOC at night. The AM band will probably end up sounding like the high end of the 40 meter ham band during the Cold War, when Russian white noise jammers jammed numerous Western shortwave broadcast stations operating on that band outside of the Americas. I am already hearing IBOC hiss during the day on stations operating on second adjacent channels with respect to IBOC stations.

The Europeans got it right with DRM. They are using it on both mediumwave (AM) and shortwave and those digital signals propagate quite well over long distances. The disadvantage to both IBOC and DRM is the expense of the receivers.

IBOC is a high-performance automobile equipped with square wheels and a rag stuffed into the carburetor. Those who designed the AM version should be garrotted!

And again I recite the mantra..Theer is no new spectrum for anything but a compatible digital system in the US. DRM is not compatible. End of story.

 

[PhilGalasso]

But K2PG, in urban areas of the US, there's something on nearly every frequency across the AM dial. NOT SO IN EUROPE. They have ROOM on the MW (AM) band for DRM. We don't.

DRM occupies a standard AM channel, not the 30 kHz occupied by an AM IBOC signal.

 

[R.F. Burns]

But K2PG, in urban areas of the US, there's something on nearly every frequency across the AM dial. NOT SO IN EUROPE. They have ROOM on the MW (AM) band for DRM. We don't.

DRM occupies a standard AM channel, not the 30 kHz occupied by an AM IBOC signal.

IBOC falls within the NRSC MAsk and meets FCC requirements. DRM doesn't

 

[PhilGalasso]

And again I recite the mantra..Theer is no new spectrum for anything but a compatible digital system in the US. DRM is not compatible. End of story.

After February 17, 2009, there will be PLENTY of room for a terrestrial, digital-only radio service in this country. With very few exceptions, the low VHF-TV channels will be vacated. That would be a natural home for digital radio.

As for compatibility, an IBOC signal that takes up nearly THREE channels on the AM band is compatible? If IBOC goes bust (and there is a good chance that it will join AM stereo and FM quad as the next electronic Edsel), the Castro government could buy some IBOC transmitters through a third country and use them quite effectively as jamming stations. The "I-Buzz" interference does remind me of the white noise jammers used by the Soviet Union at the height of the Cold War. Yes, IBOC falls inside the NRSC mask...but that mask extends into the second adjacent channels! There is still enough digital signal at the ends of that skirt to cause a very annoying hiss in many receivers. The radio in my Dodge Neon can hear it quite well.

Of course, the American consumer will be the ultimate arbiter of whether or not IBOC succeeds. If the receivers don't sell, IBOC will flop. Programming content is the thing that drives satellite receiver sales and subscriptions. FM stations can achieve "CD quality" audio in ANALOG by simply turning off their Optimods, Omnias, or other processors or by running them in the "Proof" or "Classical" mode. (How many program directors would tolerate that?) IBiquity's high licensing fees will also deter a lot of small market stations, especially struggling AMs, from adopting IBOC. If other technological advances in broadcasting were administered the way IBOC is, we would still be listening to FM in mono and watching TV in black and white.

 

[R.F. Burns]

And again I recite the mantra..Theer is no new spectrum for anything but a compatible digital system in the US. DRM is not compatible. End of story.

After February 17, 2009, there will be PLENTY of room for a terrestrial, digital-only radio service in this country. With very few exceptions, the low VHF-TV channels will be vacated. That would be a natural home for digital radio.

As for compatibility, an IBOC signal that takes up nearly THREE channels on the AM band is compatible? If IBOC goes bust (and there is a good chance that it will join AM stereo and FM quad as the next electronic Edsel), the Castro government could buy some IBOC transmitters through a third country and use them quite effectively as jamming stations. The "I-Buzz" interference does remind me of the white noise jammers used by the Soviet Union at the height of the Cold War. Yes, IBOC falls inside the NRSC mask...but that mask extends into the second adjacent channels! There is still enough digital signal at the ends of that skirt to cause a very annoying hiss in many receivers. The radio in my Dodge Neon can hear it quite well.

Of course, the American consumer will be the ultimate arbiter of whether or not IBOC succeeds. If the receivers don't sell, IBOC will flop. Programming content is the thing that drives satellite receiver sales and subscriptions. FM stations can achieve "CD quality" audio in ANALOG by simply turning off their Optimods, Omnias, or other processors or by running them in the "Proof" or "Classical" mode. (How many program directors would tolerate that?) IBiquity's high licensing fees will also deter a lot of small market stations, especially struggling AMs, from adopting IBOC. If other technological advances in broadcasting were administered the way IBOC is, we would still be listening to FM in mono and watching TV in black and white.

Like it or not yes IBOC is legal and it's way to soon to suggest that it will fail. It is already far more successful than AM stereo ever was, with more stations operating and more different radios available with more coming on line every day. Sony is coming out with a new HD table radio. in NY first adjacent analog DXing isn't possible due to the sidebands of our high power AM facilities. So whether the interference is 100% or 65& those first adjacent channels are no good for anything but getting an ID and since DXing is so unimportant today that the DXer has no weight in any consideraton, if they ever did. As to interference, I own 2 HD radio (soon to be 3) and I have no interference problem. When I tune to any of our 5 AM HD stations I have no IBOC interference. The only place I've heard complaints about IBOC sidebands are from DXers. you don't read complaints from people in any of our newspapers. No one that I know has asked what is wrong with the AM stations in NYC. Only those few AM Dxers and a few radio fans who listen to AM in wideband mode (A very small percentage of people) have anything negative to say about the introduction of IBOC and with IBOC's DSP selectivity on these radios is outstanding

 

[Mike Walker]

Yes DRM does occupy a signal 10khz AM channel. A DIFFERENT ONE FROM THE ONE SENDING ANALOG! That's a pretty important distinction, as stations are only allotted ONE of those 10khz channels. We have THOUSANDS of AM stations in this country, not the hundreds, or dozens in countries using DRM on mediumwave.

HD does indeed put information into adjacent channels. But it's at a level consistent with what has been allowed for analog. After all, it hasn't been that long since 15khz or greater modulation was not only legal, but common on AM music stations. And they were ALL OVER adjacent channels.

 

[rbrucecarter5]

HD does indeed put information into adjacent channels. But it's at a level consistent with what has been allowed for analog. After all, it hasn't been that long since 15khz or greater modulation was not only legal, but common on AM music stations. And they were ALL OVER adjacent channels.

I think it is vastly misleading to imply that the audio level of IBOC sidebands is comparable to that of wideband AM stations. All it takes is one time, tuning from the analog channel to digital sideband, especially the upper one - to convince an objective listener that the digital sidebands are much louder than the analog.

The only time I can ever remember when I heard interference 10 or more kHz away from the main channel that was actually louder was from a Spanish station in Midland, TX, that was overmodulated, distorted, and clipping. As I recall, that is exactly the way the local Hispanics wanted their music to sound. The analog clipping created harmonics that were somewhat digital in appearance on a spectrum analyzer. It is too bad the FCC turns a blind eye to such excesses.

 

[R.F. Burns]

HD does indeed put information into adjacent channels. But it's at a level consistent with what has been allowed for analog. After all, it hasn't been that long since 15khz or greater modulation was not only legal, but common on AM music stations. And they were ALL OVER adjacent channels.

I think it is vastly misleading to imply that the audio level of IBOC sidebands is comparable to that of wideband AM stations. All it takes is one time, tuning from the analog channel to digital sideband, especially the upper one - to convince an objective listener that the digital sidebands are much louder than the analog.

The only time I can ever remember when I heard interference 10 or more kHz away from the main channel that was actually louder was from a Spanish station in Midland, TX, that was overmodulated, distorted, and clipping. As I recall, that is exactly the way the local Hispanics wanted their music to sound. The analog clipping created harmonics that were somewhat digital in appearance on a spectrum analyzer. It is too bad the FCC turns a blind eye to such excesses.

I don't know how old you are but in days gone past first adjacents were unlistenable. It may not have been a problem with 1 KW local stations but here where we have many 50 KW facilities first adjacent frequencies were inaudible. Now, you might say that the interference only rendered the frequency useless 60% of the time instead of 100% of the time but it waas useless for anything other than maybe catching an ID. I believe at one time 50 KW WQXR was licensed for 20 Khz service on 1560 Khz. Forget your analog receiver with analog filtering where reciever selectivity sloaps off from center carrier down any number of DB. The problem is in the receiver. Take a look at the transmited carrier on a spectrum analyzer and you'll see that in reality the Iboc carrier falls inside the NRSC mask. Like it or not, the IBOC station is complying with the law and that's all that matters.

 

[Mike Walker]

Yeah in the 70s and 80s, AM music stations were VERY W I D E! They SMASHED adjacent channels for many miles, with EXTREME levels of pre-emphasis, and VERY BROAD high frequency response. It sounded GREAT locally, but caused interference like crazy.

Still I LOVE the sound of broadband AM. There's something very attractive (to me) about it. "The sound of a gallon (wideband audio) being squeezed into a quart jar (10khz AM channel)", I've always called it. And it sounded GOOD!

 

[Tom Wells]

I would love to hear a music intensive AM like Canada's CHOW (also 740) in HD.

Ouch! CHOW is one of the few AM fidelity showcases left.

 

[Chuck]

Yeah in the 70s and 80s, AM music stations were VERY W I D E! They SMASHED adjacent channels for many miles, with EXTREME levels of pre-emphasis, and VERY BROAD high frequency response. It sounded GREAT locally, but caused interference like crazy.

Still I LOVE the sound of broadband AM. There's something very attractive (to me) about it. "The sound of a gallon (wideband audio) being squeezed into a quart jar (10khz AM channel)", I've always called it. And it sounded GOOD!

Somehow that worked. And it really did sound good. The problem is there are probably 3 times as many AM stations now as there were back then, and there is no more space allocated to put them in. (Well very little if you count expanded band). That's bad.

I'm not sure that compounding the problem is a step in the right direction for AM. The 15KHz modulation splatter was intermittent. The IBOC sidebands are constant. I think all but the most powerful AM stations are going to have problems. I hope I'm wrong. AM has enough problems without adding new ones. I know this is supposed to be AM's salvation; for 50 KW stations in major metro's, it probably will be. The downside is everyone else loses. None-the-less, it's what we have, so we might as well figure out how to deal with it.

 

[R.F. Burns]

Yeah in the 70s and 80s, AM music stations were VERY W I D E! They SMASHED adjacent channels for many miles, with EXTREME levels of pre-emphasis, and VERY BROAD high frequency response. It sounded GREAT locally, but caused interference like crazy.

Still I LOVE the sound of broadband AM. There's something very attractive (to me) about it. "The sound of a gallon (wideband audio) being squeezed into a quart jar (10khz AM channel)", I've always called it. And it sounded GOOD!

Somehow that worked. And it really did sound good. The problem is there are probably 3 times as many AM stations now as there were back then, and there is no more space allocated to put them in. (Well very little if you count expanded band). That's bad.

I'm not sure that compounding the problem is a step in the right direction for AM. The 15KHz modulation splatter was intermittent. The IBOC sidebands are constant. I think all but the most powerful AM stations are going to have problems. I hope I'm wrong. AM has enough problems without adding new ones. I know this is supposed to be AM's salvation; for 50 KW stations in major metro's, it probably will be. The downside is everyone else loses. None-the-less, it's what we have, so we might as well figure out how to deal with it.

There are still many questions about full time IBOC that need to be answered. One important issue is the effect on low powered stations which were licensed when the level of interference from stronger neighbors was lower. In other words they were shoehorned into an already overcrowded band. Most of these station shouldn't have been licensed to begin with and now you have owners asking why the perceived rules have changed midstream. In fact the rules haven't changed, but theses stations are quickly learning that their weaker signal doesn't have quite the penetration it once did. If you own a station which depends on selling time to a deep fringe audience to survive, you're quickly learning that you are in a similar position to the fellow caught speeding on a highway. “But officer I've traveled this route for 10 years at a speed of 80 MPH and this is the first time I've received a speeding ticket”. The reply would be “just because you've gotten away with this for 10 years doesn't mean you have a right to speed”. That might sound callous but I think it represents what many small station owners will hear after they report larger operations for causing interference. In radio terms, if you own a class 1A station you don't have to protect anyone within your allotted band width. The responsibility for protection lies with those who choose to share your frequency.

 

[rbrucecarter5]

I don't know how old you are but in days gone past first adjacents were unlistenable. It may not have been a problem with 1 KW local stations but here where we have many 50 KW facilities first adjacent frequencies were inaudible. Now, you might say that the interference only rendered the frequency useless 60% of the time instead of 100% of the time but it waas useless for anything other than maybe catching an ID. I believe at one time 50 KW WQXR was licensed for 20 Khz service on 1560 Khz. Forget your analog receiver with analog filtering where reciever selectivity sloaps off from center carrier down any number of DB. The problem is in the receiver. Take a look at the transmited carrier on a spectrum analyzer and you'll see that in reality the Iboc carrier falls inside the NRSC mask. Like it or not, the IBOC station is complying with the law and that's all that matters.

I am a geezer - it appears that first adjacents were more of a problem in your area, which I assume to be urbanized East - than they were in the West. Vast portions of the band were blank when I was growing up, and the occasional first adjacent was important because it added one more station to your limited options. DX'ing was not a hobby for me, it was a way for me to hear the music I enjoyed - in a backwater town where the only options were country music, censored top-40, and Spanish.

Much of the country is still the same way. It is shocking to me to hear IBOC sideband pairs from stations hundreds of miles away - and not a trace of their analog audio in the middle. The IBOC sidebands are QUITE pervasive during the daytime, and nighttime operation is going to be a disaster.

If the FCC is incompetant enough to make this legal, broadcasters will soon discover that the burden is on them to make the band listenable again. Remember - HD won't work if sidebands from a thousand miles away jam your own sidebands. And I think this is very likely, almost inevitable.

 

[R.F. Burns]

I don't know how old you are but in days gone past first adjacents were unlistenable. It may not have been a problem with 1 KW local stations but here where we have many 50 KW facilities first adjacent frequencies were inaudible. Now, you might say that the interference only rendered the frequency useless 60% of the time instead of 100% of the time but it waas useless for anything other than maybe catching an ID. I believe at one time 50 KW WQXR was licensed for 20 Khz service on 1560 Khz. Forget your analog receiver with analog filtering where reciever selectivity sloaps off from center carrier down any number of DB. The problem is in the receiver. Take a look at the transmited carrier on a spectrum analyzer and you'll see that in reality the Iboc carrier falls inside the NRSC mask. Like it or not, the IBOC station is complying with the law and that's all that matters.

I am a geezer - it appears that first adjacents were more of a problem in your area, which I assume to be urbanized East - than they were in the West. Vast portions of the band were blank when I was growing up, and the occasional first adjacent was important because it added one more station to your limited options. DX'ing was not a hobby for me, it was a way for me to hear the music I enjoyed - in a backwater town where the only options were country music, censored top-40, and Spanish.

Much of the country is still the same way. It is shocking to me to hear IBOC sideband pairs from stations hundreds of miles away - and not a trace of their analog audio in the middle. The IBOC sidebands are QUITE pervasive during the daytime, and nighttime operation is going to be a disaster.

If the FCC is incompetant enough to make this legal, broadcasters will soon discover that the burden is on them to make the band listenable again. Remember - HD won't work if sidebands from a thousand miles away jam your own sidebands. And I think this is very likely, almost inevitable.

I'm guessing the areas you refer to are rural areas with very low population denisity. The major difference between what was and what is, is that you have access to many more choices to get your news and information today then you ever did before. We had a home in upstate NY when I was growing up and the TV received 2 or 3 stations poorly, even with a deep fringe antenna. Today with cable of satellite you'd never know you weren't in NYC where even in the 60's we had 7 VHF's and an assortment of UHF's. If you can hear those IBOC sidebands and they are loud enough to mask the analog first adjacent, maybe a nice HD radio will bring in some new digital AM signals with a noise floor that even a local AM can't beat. By the way, I do live in the North East and the population density here is the highest in the country.

 

[rbrucecarter5]

I'm guessing the areas you refer to are rural areas with very low population denisity. The major difference between what was and what is, is that you have access to many more choices to get your news and information today then you ever did before. We had a home in upstate NY when I was growing up and the TV received 2 or 3 stations poorly, even with a deep fringe antenna. Today with cable of satellite you'd never know you weren't in NYC where even in the 60's we had 7 VHF's and an assortment of UHF's. If you can hear those IBOC sidebands and they are loud enough to mask the analog first adjacent, maybe a nice HD radio will bring in some new digital AM signals with a noise floor that even a local AM can't beat. By the way, I do live in the North East and the population density here is the highest in the country.

Yep - the other 99.9% of the land area of the country that is rural. While it is true that satellite radio and satellite TV are widely available, penetration into rural areas is slow at best. But really appreciated when people finally figure out it is available and they can get into town to get the equipment (assuming they can afford it). What doesn't have good penetration is wideband internet. So my bet is on satellite radio for those folks.

I am probably not your target audience as I am in a city. But I travel extensively to rural areas. Even though the digital sidebands sound really loud, it has been widely reported that the digital signal is not robust. At least not nearly as robust as C-Quam, which actually WORKED more than over the city grade contour. No wonder it is the fallback plan of Ibiquity.