to all fellow engineers....

[RadioDoc]

Re: About those mis-placed accusations

> I've been accused of having an agenda. So I thought I would
> post my agenda so there will be no further accusations.
>
> (1) AM IBOC is unworkable at night due to interference. If
> all domestic stations go IBOC at night, I believe the AM
> band will be unusable in the Northern half of the Western
> hemisphere if not beyond, due to the digital sideband powers
> adding together through the root sum squared law to the
> background noise. Reception may only be possible a mile or
> two from the towers of even high power stations.
>
> (2) Daytime AM IBOC is wasted on talk and sports stations.
> The human voice, even with harmonics, is easily accomdated
> by the old analog system. Stereo musical beds and
> commercials on talk and sports stations did not spur sales
> of C-Quam radios, nor will they spur sales of IBOC radios.
>
> (3) Daytime IBOC on music stations requires such drastic
> bandwidth reductions that the music is almost unlistenable,
> due to group delay distortion. All discussions of radio
> bandwidth are irrelevant to group delay distortion, because
> even a low bandwidth radio will receive the harmonics of the
> audio at skewed times.
>
> (4) The lost of first adjacents on FM affects listeners
> primarily in the heavily populated East. They will protest
> the loss of first adjacents vigorously. First adjacents are
> less of an issue in the West.
>
> (5) The addition of HD2 and 3 channels increases diversity
> in programming, and is a good trade-off for the loss of
> first adjacents.
>
> (6) Surround sound is also intriguing, and a possible
> benefit of IBOC.
>
> (7) ALL benefits of FM IBOC disappear if the range is not
> good. Posts like the Boston Acoustics thread worry me -
> most suburban listeners are probably in or beyond the 30
> mile range he is describing. If HD2 and 3, and Surround are
> only usable within 20 to 30 miles of the towers, over
> relatively flat terrain like Indianapolis - it is a stunning
> disappointment. I hear that one company shipping IBOC
> radios had to upgrade the antennas they were providing.
> Coverage (HD, not analog) may be a major concern!
>
> (8) Yes - I am an AM stereo advocate. If the FCC had
> mandated AMAX standards on all radios above $50 like they
> mandated teletext for the deaf on TV's - AM music formats
> would be flourishing right now without the wait for
> consumers to adopt IBOC. The FCC could still act to mandate
> AMAX / C-Quam, and because the technology and supply
> channels are mature, it could be implemented and have market
> penetration in months instead of the years projected for
> IBOC. There are no nighttime issues, and coverage is supurb
> as well as the sound.
>
> (9) Compared to C-Quam - Ibiquity's own audio samples of
> IBOC AM sound like crap. Phase distortion similar to medium
> bandwidth streaming audio. If THIS is what we can look
> forward to on AM IBOC compared to C-Quam, give me C-Quam any
> time, it just plain sounds better. Don't take my word for
> it, go to Ibiquity's web site and hear the samples for
> yourself! I've heard better sounding SHORTWAVE.
>
> (10) Back to FM - there was NO reason to splatter adjacent
> channels with digital information. Existing services above
> 53 kHz could have been displaced by the digital sidebands,
> reducing the channel width required for IBOC. WHY were they
> not displaced? IBOC has data and auxiliary channel
> capability enough to replace it all. Could somebody have
> possibly been unsure about IBOC's success?
>
> There you go - that's my agenda. Challenge / insult me
> based on my true agenda - don't lump me with others.
>

Those are all very good points. I don't agree with all of them, but theyare well reasoned. Some of what you bring up is subjective, but on the technical side of things, I don't entirely disagree. AM IBOC has it's share of issues.<P ID="signature">______________
</P>

 

[RadioDoc]

Re: The arrogance continues...

> >> Bruce you have some great information regarding AM
> antennas
> > and DXing on your web site. Keep up the great work in
> that
> > area, but you need to better educate your self on this HD
> > Radio situation.
>
> Thank you for your compliments on my web site.
>
> As far as FM coverage - WHO has more data on coverage?
> Listeners or Engineers? A disciplined, experienced DX'er
> who travels the same exact routes day in / day out is going
> to notice any difference in the received signals of radio
> stations in their area. Time and time again, I have given
> the example of KLDE Houston, adding coverage information in
> other directions to the growing body of evidence something
> BAD is up with their coverage. Now, I'm noticing it on
> stations in the Dallas area as well. Low spots that were
> solid before, now dropping out. Coverage to the West that
> is now GONE. I present solid data, carefully taken,
> repeated many times to make sure there were no tropos or
> other atmospherics involved - and what do I get for my
> trouble? Posts about KLDE DELETED from the Houston board,
> in spite of the fact other listeners are also complaining.
> Their posts are deleted as well - how dare anybody suggest
> something is wrong with KLDE now that they have implemented
> the wonderous savior of radio - IBOC. And I get this post
> from you - I'm just a lowly listener / DX'er (never mind I
> have decades of experience at this) - how dare I challenge
> the measurements made (probably once, close in) of station
> engineers who are biased strongly towards their own station
> at the expense of all others, and who would be in for a
> sound disciplinary action by the owners if any hint of
> coverage problems surfaced. Yeah - I can really respect
> that! Talk about the fox guarding the hen house.
>
> There has been a discussion of this on another forum - where
> the discussion is obviously more objective. The conclusion?
> A possible link between stations utilizing separate
> antennas for HD and analog. If we can correlate analog
> coverage losses to this single factor, it would be a very
> valuable piece of information to stations trying to
> implement HD - warning them NOT to take an easy way out or
> they could lose much of their fringe audience. I think that
> is the spirit we should adopt here - not to marginalize,
> delete posts, ignore listeners. Instead, realize there
> really IS a problem, find out what it is, find a fix,
> publish articles, and GET IT SOLVED before it becomes a
> prime factor in the early demise of a promising technology.
> In other words - do Ibiquity's stinkin' job for them, and do
> it RIGHT this time!
>
> This would not be the first time, nor will it be the last,
> that I have picked up the pieces of somebody else's
> engineering mistakes - and not the first time, nor will it
> be the last, that I get the blame because I am the messenger
> with objective facts and measurements that challenge some 3
> piece suited manager's little fifedom. I remind you of bad
> engineering done because of intimidation, peer pressure, and
> denial of facts in the space program! Only there - lives
> were lost instead of analog coverage.
>
> The engineering on IBOC is NOT done - let's all put our
> noses to the grindstone, find the problem and FIX this puppy
> before it goes DOWN in FLAMES.
>

Bruce,

I think that this information would have been more helpful in getting your point across the first time.

To say "IBOC decreases FM coverage" is not entirely correct. It's a blanket statement.

To say "It appears that IBOC decreses FM coverage when using a separate antenna" is something entirely different, and worthy of more digging. I certainly don't have enough data on that to make a determination either way. I can say, without hesitation, that on my combined systems there has been absolutely no degradation of the analog signal. Don't forget, analog is still our bread and butter, and a lot of us wouldn't cripple it for the sake of IBOC.

I am all for open discussion here, as long as it's well reasoned. What happens is a few DX/AMS enthusiasts get in here and just simply shout their party line. They don't want to discuss, they want to accuse. More importantly, when asked to back up their accusations (a reasonable request) they point to "third party" observations, usually from other DX/AMS enthusiasts. That's all well and good, but we're in the buisiness of making money. If we get no complaints from our listeners, are we going to assume it's flawed? DX'ers "use" broadcast stations in ways that they were not meant to be used (I'm talking FM here). I am not going to shut down HD because someone from Ohio can't pick up a station in Florida anymore. Especially if the people in my area of trade don't complain. As I've said, I have not gotten a single complaint since firing up my HD signals.

I'm an engineer, like most engineers I deal best with hard, reproduceable facts and data. Prove it to me with a reproduceable experiment. Heck, I'll do the experiment if I need to. I have a very hard time with people using the phrases "Listeners everywhere..." and "Constant interference..." without anything but general opinions to back it up. If I said "Nobody has a problem with HD. Listeners LOVE it!" would you believe me? Not without asking for proof, I hope! That's all I'm looking for.

Come here, state your side, give some proof, and discuss instead of accuse. Is it so much to ask?<P ID="signature">______________
</P>

 

[Ray22]

Re: It's IBOC

> Not the same dealio at all. PD's objected to SCA's because
> you had to trade off main program channel modulation. The
> loudness guys didn't want to give up a single squashed
> percent of modulation. The SCA is also contained within the
> bandwidth of the analog signal, and there are issues of
> crosstalk into the main channel, usually solveable.

There were/are complaints of loudness loss with SCA's, but ALSO increased multi-path. Whether you had a PD that bought into this idea or not is not the point, the point I was making is NO studies have been done (that I know of, and that have been made public!) on the impact of FM IBOC on the analog signal. And I don't mean "averaged" field (coverage) readings driving around, but increased multi-path or other such issues. The IBOC carriers are also, like SCA's, right up next to the analog signal. In fact, IBOC is taking up the guard band that helped the SCA case.

> The digital is riding on the outer bands of the analog
> carrier and won't impact the analog via loss of modulation
> or crosstalk if the system is tuned properly.

There has been NO data supporting or disproving increased multi-path with IBOC turned on! The outer sidebands CAN affect the main channel analog...if you ever attempted SCA on and off studies. Again, very receiver model sensitive.
I'm just bringing up a POSSIBLE issue.

>
> And I'm not an Ibiquity supporter, just stating the facts
> ma'am.
>

 

[rbrucecarter]

Re: The arrogance continues...

I certainly appreciate your comments - I feel that there is some hope of reasoned discussion. I do have a couple of rebuttals - I am sure that won't come a shock!

Most listeners do not call a station to complain about reception. They flip the dial. Or turn on the iPod, TV, or video game. Or make a cell phone call to a buddy. What used to be a favorite station is listened to less, a new favorite chosen. It is probably comparatively rare for somebody to report a reception problem. So the absence of calls does not mean an absence of problems. Problems ARE being reported on several of the city boards on this forum, and on other radio forums. Problems that coincided with stations going IBOC. Now - if that is because someone got sloppy and took the easy way out with separate antennas - it can be addressed. But to ignore the problem because you, personally, haven't gotten calls from listeners is perhaps the tinest bit naive. Have you gone on the air with a 10 second spot requesting calls for reception problems since going IBOC? Not that your management would approve such a spot - but a whole lot of people may be silently suffering worsened reception. Its a possibility - this is something really new, and I am not completely convinced that the added power for the IBOC sidebands is overcoming the signal to noise decrease that comes from the added bandwidth. The added power is pretty small in proportion to the added bandwidth.

As far as repeatable data, here is an example of what gets deleted as "irrelevant" on the Houston board. Station: KLDE 107.5. Reception monitored on I-45 at least 50 times over a six year period, different times year, different times of day, different atmospheric conditions - before and after conversion to IBOC. Receiver, Pioneer Supertuner 3, modified with matched 150 kHz ceramic filters. Carefully aligned with calibrated equipment prior to installation. Alignment checked after reception changed to make sure the radio was not at fault.

Prior to IBOC conversion:

KLDE range to the North, fairly good fringe reception to Centerville, TX. Range to the NW, solid in Cypress subdivisions. Range to the Southeast - good to the gulf. Downtown reception, solid, no dropouts.

After IBOC conversion:

KLDE range to the North, fairly good fringe reception to just South of Huntsville, TX. Range to the NW, frequent dropouts with another station underneath in Cypress subdivisions. Range to the Southeast - good to the gulf. (Reported by additional sources) - Downtown receptions, frequent dropouts along Memorial Drive.

What about those observations is not controlled, repeatable, or scientific? If I were a chief Engineer at KLDE, I would be absolutely FRANTIC at horrifying reports like that!

Now, add to KLDE, similar experiences by listeners 30 miles from Austin, who lose Austin reception almost completely on IBOC conversion. Similar tales in Atlanta, Chicago, Indianapolis, Denver, in fact just about every city. SCARY stuff if you ask me! I'm hearing it in Dallas - IBOC conversions happen and reception craters. SOMETHING is very wrong! Bandwith related S/N, separate antennas instead of combiners, something. KLUV - drops out in low spots. It didn't used to! Now a rim shot from Farmersville that didn't convert is stronger! Ibiquity needs to hear about this analog coverage issue, get out there doing field strength measurments, and get the problem resolved - and quick - before many more people start figuring this out.

As for your comments about 1st adjacents - I agree that tropo listeners cannot realistically be accomodated. In fact, most tropos are so strong that they will completely obliterate IBOC sidebands - creating more of a problem for the IBOC station than for the DX'er. But - I am talking about 1st adjacents in suburban areas that are served by more than one city. Baltimore / Washington. Areas around New York City. Chicago suburbs. Particularly on the non-comm bands, first adjacents are common. Somebody goes IBOC - it obliterates a sizeable chunk of coverage for somebody's favorite NPR station. They are going to complain bitterly - NPR listeners may be the only ones who are vocal about such things. I notice that somebody paid off "digitaldisaster.org", which had specific examples. FCC allocations are stupid and crazy sometimes. I remember an Ann Arbor allocation on 102.7 and one in NE Detroit on 102.9 - both full powered - way less than standard spacing. Why did it happen? Who knows - but which one goes IBOC and prevents the other? How is that determined. There are nutty allocations like that all over the East coast and near large metro areas as more and more stations move in. They cannot all go IBOC!!! Or neither will be heard over most of their previous coverage area. So much for sunsetting analog radio --- it won't happen in our lifetimes because station owners of these marginal rimshots won't stand for it, and neither will their listeners.

 

[rbrucecarter5]

Look on the Dallas board in the "progress of IBOC" thread. Yet another person reporting coverage issues after conversion, this time in office buildings. I still say -something is up. These posts show up all over Radio Info, in almost every market. Don't take my word for it, just look. Whatever it is, it seems to be fairly consistant, covert - analog coverage problems. Stations that don't covert, analog coverage remains the same. Wierd because I don't have a clue what the mechanism is. But I'm NOT making a bunch of RI ID's and posting under different names. This problem is REAL. Most listeners just don't bother complaining. The real danger here is a backlash. Consumers spreading the word "digital isn't as good" without ever making the connection that they need a new radio for IBOC.

 

[CW]

In defense of IBOC (IBAC?? It is NOT an alterante channel but rather in the same channel mask..therefore it IS IBOC..HDTV is IBAC) causing less analog range, I have to chime in with personal experience....I have listened to and know KLDE's analog range quite well to the north and east for the last 20+ years...I add this goes back to Z107.5 (KZFX) and other formats/callsigns but always the same 2000ft tower site on the same 107.5 channel.YES, since the IBOC conversion, KLDE's analog range HAS decreased....it is pitiful to the north and in Conroe where it had table top reception with no issues, it now had stereo drop out in auto rcvrs, more noticable mobile flutter, etc....Areas where it could reach, it doesnt anymore..there could be other issues here (change of antenna or ??) but is that the reason?? I have never seen such a drastic change of reception after an antenna change, etc...we arent talking minor 3db or so change with KLDE.ALSO on the RadioTech list (populated by professional engineers of course there has been a thread that there IS an issue with IBOC on FM.....the digital carriers could be desensing the FM analog receiver on channel...remember, IF filters are NOT perfect and thus the digital IBOC carrier is getting into the IF..I plan to dig through the thread and let everyone here know more when I get it...

 

[CW]

Look on the Dallas board in the "progress of IBOC" thread. Yet another person reporting coverage issues after conversion, this time in office buildings. I still say -something is up. These posts show up all over Radio Info, in almost every market. Don't take my word for it, just look. Whatever it is, it seems to be fairly consistant, covert - analog coverage problems. Stations that don't covert, analog coverage remains the same. Wierd because I don't have a clue what the mechanism is. But I'm NOT making a bunch of RI ID's and posting under different names. This problem is REAL. Most listeners just don't bother complaining. The real danger here is a backlash. Consumers spreading the word "digital isn't as good" without ever making the connection that they need a new radio for IBOC.

Here is a post on the professional engineer's list (RadioTech) that concerns HD and analog FM- Clay is a good friend of mine and is Director of Engineering for Entercomm Seattle for years....He KNOWS his stuff Date: Fri, 21 Apr 2006 09:03:16 -0700From: "k7cr" <[email protected]>Subject: [RT] Re: People that live near FM transmitter site with HDHaving an analog radio become a great hissssss receiver ?This can certainly be a problem and yes it is radio selective in some cases having to do with the band-width of the Rcvr that's being offended. This is a common problem where separate antennas are used and the carrier ratio's become compromised due to different antenna vertical patterns.This can also be a problem when the analog receiver is close to the source of the HD carriers. This is a function of what happens to the receiver when given high doses of RF. This ismore common when population can get close to the antenna, as with lower elevation antennas etc. Stations that have their antennas on high mountains and/or very tall towers usually don't have this issue.With that being said, an example of how this can negatively impact equipment some distance away....for years we had monitored our Seattle FM's from the downtown studio's roof top antenna...20 stories up and 18 miles distant. When we added HD the conventional wide band mod monitors turned into pumpkins, unable to deal with the close spacing of the HD Carriers.Clay FreinwaldEntercom========================Now if the IF filters of your FM analog rcvr is not good enough, what is going to happen?Think about it before saying IBOC wont interfer with FM analog folks....it CAN....Theory doesnt always work in real life

 

[1q2w3e]

Look on the Dallas board in the "progress of IBOC" thread. Yet another person reporting coverage issues after conversion, this time in office buildings. I still say -something is up. These posts show up all over Radio Info, in almost every market. Don't take my word for it, just look. Whatever it is, it seems to be fairly consistant, covert - analog coverage problems. Stations that don't covert, analog coverage remains the same. Wierd because I don't have a clue what the mechanism is. But I'm NOT making a bunch of RI ID's and posting under different names. This problem is REAL. Most listeners just don't bother complaining. The real danger here is a backlash. Consumers spreading the word "digital isn't as good" without ever making the connection that they need a new radio for IBOC.

Here is a post on the professional engineer's list (RadioTech) that concerns HD and analog FM- Clay is a good friend of mine and is Director of Engineering for Entercomm Seattle for years....He KNOWS his stuff Date: Fri, 21 Apr 2006 09:03:16 -0700From: "k7cr" <[email protected]>Subject: [RT] Re: People that live near FM transmitter site with HDHaving an analog radio become a great hissssss receiver ?This can certainly be a problem and yes it is radio selective in some cases having to do with the band-width of the Rcvr that's being offended. This is a common problem where separate antennas are used and the carrier ratio's become compromised due to different antenna vertical patterns.This can also be a problem when the analog receiver is close to the source of the HD carriers. This is a function of what happens to the receiver when given high doses of RF. This ismore common when population can get close to the antenna, as with lower elevation antennas etc. Stations that have their antennas on high mountains and/or very tall towers usually don't have this issue.With that being said, an example of how this can negatively impact equipment some distance away....for years we had monitored our Seattle FM's from the downtown studio's roof top antenna...20 stories up and 18 miles distant. When we added HD the conventional wide band mod monitors turned into pumpkins, unable to deal with the close spacing of the HD Carriers.Clay FreinwaldEntercom========================Now if the IF filters of your FM analog rcvr is not good enough, what is going to happen?Think about it before saying IBOC wont interfer with FM analog folks....it CAN....Theory doesnt always work in real life

I would very much like to know exactly what percentage of receivers this effects. 1, maybe 2%???

 

[ChiefEngineer]

Re: It's IBOC

One thing that is REALLY offensive to me is how the observations of LISTENERS are marginalized and only the opinions of station owners and broadcast engineers are respected. When it comes to discerning the performance of a station, it is the listeners who have the overwhelming majority of observational data. Daily drives to work - along the same routes, with the same equipment being used day in, day out, under various meteorological conditions - come a lot closer to be controlled experiments than a single drive around the fringes by a broadcast engineer, no matter how much expensive gear he might have. Also - a broadcast engineer or owner is completely biased towards their own station / stations and completely uninterested in how their station might affect adjacents. Listeners all over the country are coming up with decreased coverage for FM stations running IBOC, as much as 60 miles. Listeners are hearing massive IBOC interference from AM stations running IBOC - hearing the sidebands over 300 miles away in some cases! Yet all of these accounts are marginalized, made fun of, sluffed off by arrogant "its your radio" comments. That - or "I've got the credentials you don't" or "I made field strength measurements that showed no difference", etc. Yet, in spite of arrogance, the body of evidence for FM coverage decreases and AM interference builds. These problems will not go away because station owners, Ibiquity, and broadcast engineers wish them to go away. Unless they happen to be named Harry Potter and can wave a magic wand to alter the laws of Physics at will. Ignore these problems and marginalize people who report them if you want - but time will prove the listeners correct as they abandon radio for XM, Sirius, and iPods. Coverage and interference are issues you dare not ignore, because they affect the listening experience.

What do we do???Clear Channel has cash to spend, companies (Harris/BE/Nautel) see cash in new transmitters ("HD ready"), and listeners see this as another new technology that doesn't work and is a roadblock to the relationship they have developed with their local station.

 

[1q2w3e]

Re: It's IBOC

One thing that is REALLY offensive to me is how the observations of LISTENERS are marginalized and only the opinions of station owners and broadcast engineers are respected. When it comes to discerning the performance of a station, it is the listeners who have the overwhelming majority of observational data. Daily drives to work - along the same routes, with the same equipment being used day in, day out, under various meteorological conditions - come a lot closer to be controlled experiments than a single drive around the fringes by a broadcast engineer, no matter how much expensive gear he might have. Also - a broadcast engineer or owner is completely biased towards their own station / stations and completely uninterested in how their station might affect adjacents. Listeners all over the country are coming up with decreased coverage for FM stations running IBOC, as much as 60 miles. Listeners are hearing massive IBOC interference from AM stations running IBOC - hearing the sidebands over 300 miles away in some cases! Yet all of these accounts are marginalized, made fun of, sluffed off by arrogant "its your radio" comments. That - or "I've got the credentials you don't" or "I made field strength measurements that showed no difference", etc. Yet, in spite of arrogance, the body of evidence for FM coverage decreases and AM interference builds. These problems will not go away because station owners, Ibiquity, and broadcast engineers wish them to go away. Unless they happen to be named Harry Potter and can wave a magic wand to alter the laws of Physics at will. Ignore these problems and marginalize people who report them if you want - but time will prove the listeners correct as they abandon radio for XM, Sirius, and iPods. Coverage and interference are issues you dare not ignore, because they affect the listening experience.

What do we do???Clear Channel has cash to spend, companies (Harris/BE/Nautel) see cash in new transmitters ("HD ready"), and listeners see this as another new technology that doesn't work and is a roadblock to the relationship they have developed with their local station.

Not only Clear CHannel, but CBE, Entercomm, and so on. Explain to me how the listener sees this doesnt work?