Technical question about HD radio

[Len14043]

While listening the WEBN (102.7) in HD 35 miles north of Cincinnati, I tuned to the ajacients i.e. 102.5 and 102.9 and heard audio on both channels. How is this possible when WEBN's digital sidebands are on 102.5 and 102.7?

 

[IBOCRocks]

While listening the WEBN (102.7) in HD 35 miles north of Cincinnati, I tuned to the ajacients i.e. 102.5 and 102.9 and heard audio on both channels. How is this possible when WEBN's digital sidebands are on 102.5 and 102.7?

Because they aren't on 102.5 and 102.9. They're close, though. That's the dirty little secret. With a decent, modern radio, all of this "interference" from FM-IBOC simply isn't there.

 

[Len14043]

While listening the WEBN (102.7) in HD 35 miles north of Cincinnati, I tuned to the ajacients i.e. 102.5 and 102.9 and heard audio on both channels.  How is this possible when WEBN's digital sidebands are on 102.5 and 102.7? 

On my original post, I meant to say "How is this possible when WEBN's digital sidebands are on 102.5 and 102.9". Sorry.  Phrased another way, How is it possible to hear 102.7 in HD, while 102.5 and 102.9 were occupied by other stations instead of digital hash?

 

[IBOCRocks]

While listening the WEBN (102.7) in HD 35 miles north of Cincinnati, I tuned to the ajacients i.e. 102.5 and 102.9 and heard audio on both channels. How is this possible when WEBN's digital sidebands are on 102.5 and 102.7?

On my original post, I meant to say "How is this possible when WEBN's digital sidebands are on 102.5 and 102.9". Sorry. Phrased another way, How is it possible to hear 102.7 in HD, while 102.5 and 102.9 were occupied by other stations instead of digital hash?

Simply put, you shouldn't hear digital hash on 102.5 and 102.9. The "hash" is set just outside the carrier on 102.7. Now, if you were right at 102.7's transmitter site, you may hear the digital hash, but you'd probably have analog interference at that point as well.

Here's one for you...I can hear an HD or analog signal on 94.5 and 94.7 while sitting in the same spot about halfway between the transmitter sites!

 

[SayNoToIBOC]

IBOCRocks wrote": Because they aren't on 102.5 and 102.9. They're close, though. That's the dirty little secret. With a decent, modern radio, all of this "interference" from FM-IBOC simply isn't there".

You're dreaming, buddy - THIS is HD Radio's dirty little secret:

http://www.orbitcast.com/archives/hd-radios-dirty-little-secret.html

 

[radioskeptic]

In response to Len14043’s follow-up question (“On my original post, I meant to say ‘How is this possible when WEBN's digital sidebands are on 102.5 and 102.9’. Sorry. Phrased another way, How is it possible to hear 102.7 in HD, while 102.5 and 102.9 were occupied by other stations instead of digital hash?”), IBOCRocks replied:

“Simply put, you shouldn't hear digital hash on 102.5 and 102.9. The ‘hash’ is set just outside the carrier on 102.7. Now, if you were right at 102.7's transmitter site, you may hear the digital hash, but you'd probably have analog interference at that point as well.”

What does he mean by “The ‘hash’ is set just outside the carrier”?

Actually, the digital signals for 102.7 are inside the channels of 102.5 and 103.9. (See iNiquity’s own diagram at http://beradio.com/currents/radio_currents_071706/index.html#fm. It’s in the fourth story, and it has links. And note that they’re asking to widen the digital mask!)

At 40 dB below the analog carrier level, the “HD1” signals (which are between 129 and 199 kHz from the FM carrier) can’t have nearly the service area of the analog signal, especially when short-spaced first-adjacents produce interference! But they can interfere with your reception of a distant first adjacent that you might otherwise be able to hear if you’re close enough to the transmitter.

Note to IBOCRocks: A carrier frequency is not a channel, so you can be on it or off it, but not inside or outside of it. And yes, FM signals do have carrier frequencies and sidebands, though the pattern of FM sidebands is different from, and far more complex than, that of AM sidebands. I suggest you get a basic textbook on electronics and brush up on theory if you want to be an oracle on technical matters, but why would you? Your real purpose in posting here is to spread heat, not light. From the tone of your postings, it’s apparent that your only goal is to defend iNiquity’s half-baked technology from criticism, however legitimate.

 

[vsa]

Amen!

 

[SayNoToIBOC]

Amen !

 

[IBOCRocks]

In response to Len14043’s follow-up question (“On my original post, I meant to say ‘How is this possible when WEBN's digital sidebands are on 102.5 and 102.9’. Sorry. Phrased another way, How is it possible to hear 102.7 in HD, while 102.5 and 102.9 were occupied by other stations instead of digital hash?”), IBOCRocks replied:

“Simply put, you shouldn't hear digital hash on 102.5 and 102.9. The ‘hash’ is set just outside the carrier on 102.7. Now, if you were right at 102.7's transmitter site, you may hear the digital hash, but you'd probably have analog interference at that point as well.”

What does he mean by “The ‘hash’ is set just outside the carrier”?

Actually, the digital signals for 102.7 are inside the channels of 102.5 and 103.9. (See iNiquity’s own diagram at http://beradio.com/currents/radio_currents_071706/index.html#fm. It’s in the fourth story, and it has links. And note that they’re asking to widen the digital mask!)

At 40 dB below the analog carrier level, the “HD1” signals (which are between 129 and 199 kHz from the FM carrier) can’t have nearly the service area of the analog signal, especially when short-spaced first-adjacents produce interference! But they can interfere with your reception of a distant first adjacent that you might otherwise be able to hear if you’re close enough to the transmitter.

Note to IBOCRocks: A carrier frequency is not a channel, so you can be on it or off it, but not inside or outside of it. And yes, FM signals do have carrier frequencies and sidebands, though the pattern of FM sidebands is different from, and far more complex than, that of AM sidebands. I suggest you get a basic textbook on electronics and brush up on theory if you want to be an oracle on technical matters, but why would you? Your real purpose in posting here is to spread heat, not light. From the tone of your postings, it’s apparent that your only goal is to defend iNiquity’s half-baked technology from criticism, however legitimate.

Interesting. You have no idea who I am, yet I need to "brush up" on my electronics. I do like how you take the semantics of what I say and use it to try and discredit what I write. How many HD systems have you installed? I've done several, and have done the spectral analysis and mask measurements on each of them, so I don't need your "help" to understand how it all works. I was describing how IBOC works to a non-technical person.

I can tell by YOUR tone ("iNiquity"...how cute!) that you are here to try and discredit anything positive that anyone has to say.

Obviously, I'm in the presence of sheer genious, so I'll just sit back and wait for the inevitable snarky reply from the desparate souls on the anti-IBOC crew.

Thanks for trying to school me...didn't need it though. You may want to use that education to teach SayNo and SUPERCASTER. They like to make wild claims while not having a clue how the stufff works.

 

[SUPERCASTER]

The iBiquity/HD Radio adjacent channel system is defective, inferior, unnecessary, and is politically driven by lobbyists, and supported by a cartel. HD Radio never had a comprehensive, independent, impartial, engineering, reception or interference impact study done. To adopt such an unnecessary adjacent channel system as a standard for digital broadcasting, that could seriously adversely effect hundreds of stations, and millions of listeners, could not be considered an informed engineering decision, but totally politically driven.
Having installed HD transmitting equipment only indicates to me you have a personal and financial interest in HD Radio's success that is influencing and biasing your views and statements.
Installing HD transmitting equipment has nothing to do with the impartial detailed engineering studies that should be made before this problematic HD system gets final FCC approval.
Your totally baseless and uninformed criticisms of stangers is typical of an ignorent bigot, and your opinions
of others are inflamatory, spurious, and have no more substance then the electrons they are written on.
Having a few thousand HD Radio's in the hands of a miniscule number of technicians and early adopters is not a reason to disrupt radio broadcasting forever for many hundreds of millions of listeners in North America, nor interfere with station frequency asignments to the point where some stations providing valuable local service to their communities may be forced to shut down.
There is an alternative FM digital broadcasting system that has already been accepted by the FCC, does not use adjacent channels, is totally compatible with the current station assignments, has equal or better coverage, is simpler, open, and much less costly.
FMeXtra www.dreinc.com
AM digital may have to wait for a compatible In Band On Channel system suitable for night time operation.
Your attacks and criticism of HD opponents, and statements about HD Radio/iBiquity/HD consortium (Alliance) are totally biased by your involvement, as you claim you are involved in the installation, operation and adoption of this flawed, unnecessary technology.

 

[SayNoToIBOC]

IBOCRocks wrote: "Interesting. You have no idea who I am, yet I need to "brush up" on my electronics. I do like how you take the semantics of what I say and use it to try and discredit what I write. How many HD systems have you installed? I've done several, and have done the spectral analysis and mask measurements on each of them, so I don't need your "help" to understand how it all works. I was describing how IBOC works to a non-technical person. I can tell by YOUR tone ("iNiquity"...how cute!) that you are here to try and discredit anything positive that anyone has to say. Obviously, I'm in the presence of sheer genious, so I'll just sit back and wait for the inevitable snarky reply from the desparate souls on the anti-IBOC crew. Thanks for trying to school me...didn't need it though. You may want to use that education to teach SayNo and SUPERCASTER. They like to make wild claims while not having a clue how the stufff works."

Hey IBOCRocks, I'm here to discredit HD Radio, too !

 

[radioskeptic]

Sorry about taking so long to reply, but I’ve been “off-line” since about 2 PM Saturday (9/2).

“You have no idea who I am,” wrote IBOCRocks. But in fact, I strongly suspected that he had some kind of financial interest in the success of IBOC, and he very helpfully confirmed that when he said that he has installed “several” IBOC systems.

As for me, I can proudly say I’ve installed none. That’s not surprising, though, since I’ve been out of radio for over a decade -- and I think I made the right career choice in leaving the field, in view of baleful effects the wave of consolidation encouraged by the notorious 1996 Telecom Act has had on the industry!

But while I suspected that IBOCRocks and the other IBOC advocates who are regulars on this board (1q2w3e, autopaint-1, I.B.Iquity and pullitin) had some sort of financial interest, and considered them verbal bullies, I never pictured them as all-around “losers,” the way they’ve tried to portray SayNoToIBOC, Supercaster, vsa, audiophile and other IBOC opponents.

I doubt that the IBOC opponents are adolescents, or arrested adolescents, as the IBOC advocates suggest; but if they were, how would that invalidate their criticisms of the system? (Is patriotism the last refuge of the scoundrel? Not always. Sometimes the ad hominem attack is!)

But let’s turn back to the question of IBOC and first-adjacents.

There are a dozen Class B stations in New York City, or in nearby North Jersey towns, with Class B first-adjacents in Philadelphia, or in nearby South Jersey or SE Pennsylvania towns Let’s just look at one such pair as an example.

New York’s WFNY is on 92.3, and Philadelphia’s WXTU is on 92.5. Look at their 60 dBu contours – AND their 40 dBu’s – as shown on the Radio-Locator maps. (Just go to www.radio-locator.com and enter the call letters, then click on “View Coverage.”) You’ll see that each station’s 40 overlaps the other’s 60, meaning the difference is less than 20 dB at some locations. And remember that the digital “HD-1” signal of each station is 40 dB below the level of its own analog signal.

It’s obvious that the unplotted 30dBu of each station would also overlap the other’s 70 dBu (the city-grade, or principal community, contour). And of course, in a broad swath of central New Jersey, some of these NY/Phila first-adjacent pairs have a difference in analog signal strength of less than 10 dB. With first-adjacents this close, how can IBOC signals NOT suffer interference – at times even within their city-grade contours, depending on propagation conditions?

(A suggestion for SayNoToIBOC: Maryland, too, is part of the East Coast "Megalopolis," and should be a happy hunting ground for more such unhappy first-adjacent pairs!)

 

[SayNoToIBOC]

"(A suggestion for SayNoToIBOC: Maryland, too, is part of the East Coast "Megalopolis," and should be a happy hunting ground for more such unhappy first-adjacent pairs!)"

Hey, thanks for the support to the anti-IBOC'ers ! I only listen to nighttime AM. Actually, I hold a CIA TS/SCI/poly clearance, and if I had any sort of blemished past, I wouldn't be holding this clearance (believe me, it a real pain to get). I too, believe these pro-IBOC'ers must have some sort of direct interest in HD Radio/IBOC (David, certainly has). It is funny, that the first review on Amazon for the Receptor HD was obviously written by someone in the HD Radio Cartel, and it is dated, even before the radio was in stock. A lot of my rants are just to bother these sh*lls, but the posts are truthful. Should I try daytime FM for the first-adjacents ?

 

[audiophile.]

I'd like to comment on earlier question on the digital signals.

The digital signals are transmitted fron 123 to 198 kHz out from the main FM carrier (yes...right on top of the first adjacent station which is 100 to 300 kHz out!).

It is possible if the receiver that has an IF bandwidth as wide as barn door you will hear hiss and analog-type distortion mixed together. This will also depend on the strength of the digital signal in relation to the analog signal(s) at the time of reception.

I surmise some of the broadcasters are keeping a low profile (and lower digital power level) until IBOC is approved to avoid listener complaints and 'stirring the anti-IBOC pot'.

In my OEM radio car all I hear a loud coarse hiss on first adjacents of IBOC stations (and in many cases where FM stations where receivable before).

 

[IBOCRocks]

I surmise some of the broadcasters are keeping a low profile (and lower digital power level) until IBOC is approved to avoid listener complaints and 'stirring the anti-IBOC pot'.

I surmise that that is a pretty wild accusation, and I'm offended. I certainly haven't done that with any stations I've dealt with, and can say with 100% certainty that I have not met another Engineer who has done that either. To do so would be unethical (and foolish, since you'd lose HD coverage by doing that).

I suggest that you get some proof before throwing out things like that.

The conspiracy thoery stuff if getting old.

 

[audiophile.]

I'm not sure why you would be personally offended. As screen name I don't even know who, or where you are!

Furthermore there is nothing illegal or wrong about running the digital transmission level conservatively. Several AM stations have shutdown their digital signals because of complaints, so it would seem plausable that some have reduced the power also.

We can not put IBOC signals on the air and call it 'research' (IE It's OK (or not OK) on my radio). Too many variables. The problem here is lack of independant scientific studies on IBOC. Then this whole discussion becomes moot when a real independant study is done.

What you do at your station, as long as it is not overpowered, is up to you.

PS I do know for a fact that some broadcasters are using a rule loophole with IBOC to gain themselfs a significant advantage. That's all I will say for now....

 

[IBOCRocks]

I'm not sure why you would be personally offended. As screen name I don't even know who, or where you are!

Furthermore there is nothing illegal or wrong about running the digital transmission level conservatively. Several AM stations have shutdown their digital signals because of complaints, so it would seem plausable that some have reduced the power also.

We can not put IBOC signals on the air and call it 'research' (IE It's OK (or not OK) on my radio). Too many variables. The problem here is lack of independant scientific studies on IBOC. Then this whole discussion becomes moot when a real independant study is done.

What you do at your station, as long as it is not overpowered, is up to you.

PS I do know for a fact that some broadcasters are using a rule loophole with IBOC to gain themselfs a significant advantage. That's all I will say for now....

Easy. I'm offended simply because you are suggesting that activities are occuring that simply aren't. I think that it's simply more "secret squirrel" accusations by a group that thinks that this is one big conspiracy. Since I fall into the class of people running IBOC, I take offense that someone would think that we'd purpously "cripple" the IBOC carriers, only to turn them up after a ruling. It simply isn't necessary - I have not received a single complaint from ANY of the installs I've done, and I am running fully to spec.

Again, a lot of tinfoil hat stuff, but that's all. In fact, let's look at your claim that there is no independant study. There's no reason why there couldn't be one. So what's holding you guys back? Do it, and prove your claims!

As for loopholes...some may be using a loophole, though it's pretty convenient that you can lob that out without proof. I'm not aware of any loopholes out there that could gain anyone a "significant" advantage, but if there's a problem, then the loophole will be closed. Simple.

 

[audiophile.]

It simply isn't necessary - I have not received a single complaint from ANY of the installs I've done, and I am running fully to spec.

Yes, but how many average listeners would know to call you? I haven't found any average listeners who can extract a legal ID out of the hiss...

Again, a lot of tinfoil hat stuff, but that's all. In fact, let's look at your claim that there is no independant study. There's no reason why there couldn't be one. So what's holding you guys back? Do it, and prove your claims!

So are you suggesting we go to Congress to authorize a true independant study, like the Mitre report?

As for loopholes...some may be using a loophole, though it's pretty convenient that you can lob that out without proof. I'm not aware of any loopholes out there that could gain anyone a "significant" advantage, but if there's a problem, then the loophole will be closed. Simple.

Well, I'm not sure I want to let the cat out of the bag, but it is very real and people are doing it. I'll give one hint: The suggestion was 'use the loophole now' and hope that it could be grandfathered.

 

[IBOCRocks]

It simply isn't necessary - I have not received a single complaint from ANY of the installs I've done, and I am running fully to spec.

Yes, but how many average listeners would know to call you? I haven't found any average listeners who can extract a legal ID out of the hiss...

Again, a lot of tinfoil hat stuff, but that's all. In fact, let's look at your claim that there is no independant study. There's no reason why there couldn't be one. So what's holding you guys back? Do it, and prove your claims!

So are you suggesting we go to Congress to authorize a true independant study, like the Mitre report?

As for loopholes...some may be using a loophole, though it's pretty convenient that you can lob that out without proof. I'm not aware of any loopholes out there that could gain anyone a "significant" advantage, but if there's a problem, then the loophole will be closed. Simple.

Well, I'm not sure I want to let the cat out of the bag, but it is very real and people are doing it. I'll give one hint: The suggestion was 'use the loophole now' and hope that it could be grandfathered.

The listeners could call me, they could call the station I was "interfering" with, which could call me. The stations themselves could call me. Bottom line is that nobody is complaining. Period.

I don't think Congress needs to authorize anything. If the anti-IBOC crowd wants an independant study, let them do it. This issue isn't worthy of a Congress-authorized anything. The small, yet vocal anti-IBOC crowd are the only people making the allegations...do your studies and back up the claims! It's pretty obvious so far that the general public doesn't care about HD either way. It's mostly DX'ers, diciples of Leonard Kahn, or the group of broadcasters who are against iBiquity's licensing.

Again, if the general public is smart enough to call us because their garage door opener no longer works, I think they could call someone if there's a bad hiss somewhere. It's just not happening. If it were, you guys wouldn't need to be here.

 

[audiophile.]

The listeners could call me, they could call the station I was "interfering" with, which could call me. The stations themselves could call me. Bottom line is that nobody is complaining. Period.

I don't know the specifics of what you installed. Maybe it's not bothering anybody in your instance, or then again maybe they don't know who or what is causing it (maybe they assume their radio antenna is busted, because it sounds indentical to white noise).

I don't think Congress needs to authorize anything. If the anti-IBOC crowd wants an independant study, let them do it. This issue isn't worthy of a Congress-authorized anything. The small, yet vocal anti-IBOC crowd are the only people making the allegations...do your studies and back up the claims! It's pretty obvious so far that the general public doesn't care about HD either way. It's mostly DX'ers, diciples of Leonard Kahn, or the group of broadcasters who are against iBiquity's licensing.

So if we do this study will you accept the results, or just reject it too as DX'ers bias? To me it seems partially futile because you will reject the results unless it is independant.

Again, if the general public is smart enough to call us because their garage door opener no longer works, I think they could call someone if there's a bad hiss somewhere. It's just not happening. If it were, you guys wouldn't need to be here.

Apples to oranges. If you are close enough to make the garage door opener not work to overload, then I think it may be safe to assume they may be able to tell who is causing the problem since probably every piece of electronic gear in this home is whispering with your audio.