AM HD TURNOFF PACE ACCELERATES

[tomservo]

Zach,

Apparently you are not familiar with the way FM assignments are jammed side-by-side in the reserved ("educational") part of the band in any large city.

Can you give me an example of areas where there are education assignment side-by-side? I (for now) live in a mostly rural area and everything's pretty well spaced out. Public radio gets one frequency and American Family Radio gets everything else.

 

[Play Freebird]

While it's true that the sidebands wipe out everything on either side of a channel on FM, there is not a single market I'm aware of where two stations' contours overlap when they're first adjacents.

There are a bunch between New York and Washington. Here are some examples:

WUSL 98.9 and WAWZ 99.1 - protected contours overlap between northeast Philly and Princeton. Practically all of Mercer County, NJ (the Trenton market) is in the interference zone.
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM274154.html
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM667957.html

WBEB 101.1 and WROZ 101.3 - overlap in an area several miles west of Coatesville, PA
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM73954.html
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM549669.html

WIOV 105.1 and WDAS-FM 105.3 - Almost all of Chester County, PA (one of the Philadelphia metro counties) is in the overlap area. West Chester, as shown on the FCC map, is the county seat.
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM269148.html
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM181766.html

WPRS 104.1 and WZFT 104.3 -- Lots of overlap in the densely populated area between Washington and Baltimore, near BWI
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM1194957.html
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM1290754.html

WHCN 105.9 and WBLI 106.1 -- Overlap in CT between Bridgeport and New Haven
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM126364.html
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM657080.html

Then you have the grandfathered stations, like KRTH and KATY that LO mentioned.

For another example, check WTSS 102.5 vs WLGZ 102.7. The WTSS protected contour almost reaches the WLGZ transmitter site on the west side of Rochester.

http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM591910.html
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM228777.html

I could name several more, but you get the idea.

 

[ajc_trw]

While it's true that the sidebands wipe out everything on either side of a channel on FM, there is not a single market I'm aware of where two stations' contours overlap when they're first adjacents.

There are a bunch between New York and Washington. Here are some examples:

WUSL 98.9 and WAWZ 99.1 - protected contours overlap between northeast Philly and Princeton. Practically all of Mercer County, NJ (the Trenton market) is in the interference zone.
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM274154.html
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM667957.html

WBEB 101.1 and WROZ 101.3 - overlap in an area several miles west of Coatesville, PA
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM73954.html
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM549669.html

WIOV 105.1 and WDAS-FM 105.3 - Almost all of Chester County, PA (one of the Philadelphia metro counties) is in the overlap area. West Chester, as shown on the FCC map, is the county seat.
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM269148.html
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM181766.html

WPRS 104.1 and WZFT 104.3 -- Lots of overlap in the densely populated area between Washington and Baltimore, near BWI
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM1194957.html
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM1290754.html

WHCN 105.9 and WBLI 106.1 -- Overlap in CT between Bridgeport and New Haven
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM126364.html
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM657080.html

Then you have the grandfathered stations, like KRTH and KATY that LO mentioned.

For another example, check WTSS 102.5 vs WLGZ 102.7. The WTSS protected contour almost reaches the WLGZ transmitter site on the west side of Rochester.

http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM591910.html
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM228777.html

I could name several more, but you get the idea.

Try these two

http://www.fcc.gov/fcc-bin/fmq?list=0&facid=72981

WENJ 97.3

http://www.fcc.gov/fcc-bin/fmq?list=0&facid=47427

WPEN 97.5

 

[W2JUV_AL]

For another example, check WTSS 102.5 vs WLGZ 102.7. The WTSS protected contour almost reaches the WLGZ transmitter site on the west side of Rochester.

I could be all wet on this but I think WTSS is a "grandfathered" class B that puts out 100kW.
The link shows a plot of their 54dBu contour, but is that the "protected" contour for a station that exceeds its licensed class? Seems like I was told once that protection only extends to the contour allowed by the license class, in this case 50kW at 500ft HAAT.

 

[Schroedingers Cat]

There are plenty of first adjacent short spaced commercial stations all over Zone I. They complied with previous rules, but often with Low ERP/Low HAAT facilities. Protection was INCREASED for Commercial Class Bs from actual licensed 1 mV/m to maximum facility for class 0.5 mV/m back in the early 1960s when the Table Of Allotments and Distance Separation Requirements were adopted.

Class As almost always had de facto service beyond the 1 mV/m before IBOC.

And I can give you some examples of IBOC first adjacent interference within the predicted 0.5 mV/m contour of AM stations. This is partly because the M-3 Map is inaccuarate, overestimating service in some areas and underestimating it in others.

DXing is in many ways like an extension of listening to local stations under extreme stressed conditions within predicted service areas.

 

[Play Freebird]

I could be all wet on this but I think WTSS is a "grandfathered" class B that puts out 100kW.
The link shows a plot of their 54dBu contour, but is that the "protected" contour for a station that exceeds its licensed class? Seems like I was told once that protection only extends to the contour allowed by the license class, in this case 50kW at 500ft HAAT.

That's correct, but the FCC rules allow WTSS to operate with IBOC at -20 dB with respect to the full grandfathered 110 kW power -- in other words, the digital power can be run as high as 1.1 kW.

If WTSS actually complied with the normal Class B limit for a HAAT of 355 meters, the maximum analog power would be 8.6 kW. At -10 dB digital injection, this works out to 860 watts. But WTSS is already allowed to exceed this by about 1 dB, so the interference to WLGZ is substantial.

 

[local oscillator]

Zach, now I understand your comments. I didn't realize that you live in the wide open spaces where stations aren't squeezed in to within an inch of their lives. The FM band in Zone I is a very, very different place!

W2JUV_AL, you're absolutely correct in saying that the protected contour of super-powered stations (i.e. WTSS) is in fact only actually protected to the extent provided by the Table of Separations -- which IMHO pretty much defeats the purpose of running superpower. The real problem is what they do TO their neighbors on the dial -- they cause an inordinate amount of interference, both analog and digital. Other stations generally have had to accept the analog interference, since the super-powered stations in almost all cases predate the stations receiving the interference. Obviously, IBOC interference is a totally different situation.

Play Freebird, you've hit the nail on the head! In addition to WTSS, there are two stations in Grand Rapids, MI (WBCT and WOOD-FM) that are worse, and there several in CA that are even more so.

 

[tomservo]

When I saw the maps of WUSL and WAWZ, I have to admit my jaw dropped.

I knew that the Band I region was more crowded but I had no idea there were so many examples of first adjacents with overlapping contours like that.

That really helps me understand why some are so upset over the sidebands on FM. Where I live (for the next week, anyway) the band is full but well spaced and having two strong signals right next to each other is a rarity reserved for strong band openings.

I'd be interested to know how these tightly packed stations fare, analog coverage wise in the overlapping areas. Most modern car radios can probably pick the two apart easily, but what must it have been like back in the 70's, or with a modern cheap Chinese dollar store piece of junk?

And another thing that really made me go "wow" was fact that superpowers can run IBOC relative to their grandfathered power. That REALLY should not be; the HD is a "new addition" and should fall under the current power rules, not the grandfathered rule. That's really, really stupid.

 

[Play Freebird]

I'd be interested to know how these tightly packed stations fare, analog coverage wise in the overlapping areas. Most modern car radios can probably pick the two apart easily, but what must it have been like back in the 70's, or with a modern cheap Chinese dollar store piece of junk?

This is a good question. Older receivers (with IF transformers and AFC) had big problems separating first-adjacents. My first FM radio even had trouble with second and third adjacents, mainly because the AFC would jump to the stronger signal -- and if I defeated AFC, then it would drift off channel.

However, selectivity has greatly improved since ceramic IF filters have become the norm, and now we have the advantage of DSP chips with a remarkable ability to filter out adjacent channel interference. If you want to experience this kind of performance for 25 bucks plus shipping, order the Grundig G8 portable on sale at the National Geographic online store. (rtc posted the link a couple of weeks ago.)This receiver is based on SILABS's Si4734 chip with a typical first-adjacent FM selectivity of 50 dB. (The Zune also uses this chip) For more info, download the datasheet here:

http://www.silabs.com/products/audiovideo/amfmreceivers/Pages/Si473435.aspx

The Si4734 is a high-end "receiver on a chip" in a tiny 3 X 3 mm package with LW, MW, SW and 65-108 MHz stereo FM capability all included -- the Si4735 adds RDS. Mouser sells them in unit quantities for $11.96 and in lots of 100 for $7.65, so manufacturers who buy them in the thousands are probably paying less than 3 bucks. Just add tuning/volume controls, display, and audio stage and you have a radio!

http://edageek.com/2007/11/12/silicon-labs-si4734-35/

Oh, another neat thing about the G8 is its FM signal strength meter which reads in 1 dB steps, nearly linear from the noise floor up to 1000 uV.

The point I want to make is that these grandfathered first-adjacent analog-to-analog short spacings can be handled quite well by new (inexpensive) receiver technology - but when IBOC is added, the interference becomes co-channel. Then, there's no solution other than to install a directional receive antenna, which is impractical in most situations.

 

[BRNout]

WIOV 105.1 and WDAS-FM 105.3 - Almost all of Chester County, PA (one of the Philadelphia metro counties) is in the overlap area. West Chester, as shown on the FCC map, is the county seat.
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM269148.html
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM181766.html

While you're right on target in most cases, I think you exaggerate a bit on this one. It's not "most" of Chester County that's in the interference zone; more like the northwestern 25% of the county is. WDAS-FM is dominant over most of the county with that portion being the exception where the two stations are more evenly matched. I agree that they are still spaced too closely, but the reality is that WIOV ends up being the loser in the majority of the county. You see, those FCC maps ignore topography and there are hills between West Chester/Exton/Coatesville and Reading. This blocks some of WIOV's signal in certain areas. As a result, WIOV's range into Chester County is exaggerated. Yes, I recall WIOV and WDAS-FM being about equal in the Lionville area - but travel a mile or two away (or down a hill) and the advantage quickly turns to 'DAS-FM.

Another 2 markets with quite a bit of overlap are Chicago and Milwaukee. In most cases, the net result has been that most Milwaukee market signals are no longer receivable as close to Chicago as they once were and vice versa. Given that they weren't "supposed to be" receivable in those places, the FCC sleeps quite well at night - thank you very much.

With the power increases, it gets even worse - WBBM-FM seems to be the worst offender in that it steps all over WKLH in places where the two signals should be equivalent. Another good one is the co-owned Bonneville pair of WDRV 97.1 Chicago and WWDV 96.9 Zion, IL (serving the southern part of the MKE market and far N. IL). The HD sidebands from WWDV wipe out WDRV on most radios from Gurnee, IL northward. And, WDRV's sidebands do the same to WWDV once you get into Cook County. As they are co-owned simulcasters, there's no foul and no harm. But, if they weren't, there would be big trouble.

The whole concept is a mess and it amazes me as to how short-sighted the FCC has been in whoring themselves out to Ibiquity.

 

[Tom Wells]

I have to admit, most of my FM listening in the past 6 months has been on a mono FM 1966 car radio.
Same car and radio for 33 years, and same general region and signals to compare.

I don't know for sure if it has AFC built in, (I'm thinking it does) but it doesn't drift noticeably.
I'm not having any real trouble with selectivity, but I've never lived between two close spaced markets.
I can still hear WCCQ 98.3 fairly well, despite the iboc from 98.7 WFMT.
I don't think I ever could pick up anything on 98.5 anyway.
Same with catches of Michigan stations from across the lake.

This may be a result of the high elevations for major Chicago FM, as opposed to much higher actual RF power being
used elsewhere without such elevations. On the other hand, this may be why FM HD reception on my wife's
Kenwood in the car does poorly with so much multipath from continuous aircraft overhead...

I DO hear more and louder mulitpath noise incidents affecting stations using iboc, and maybe an odd
2-3 db apparent loudness change, up and down, unrelated to program material.

I don't need to say anything new about the AM...sure was nice to hear how WGCI "really" sounds in that brief respite.
The sound is still good underneath all that data hash. Hasten the day of the bad sectors, O Lord.

 

[local oscillator]

The whole concept is a mess and it amazes me as to how short-sighted the FCC has been in whoring themselves out to Ibiquity.

First time I've heard it put that way, but yes, that's the whole problem in a nutshell!

 

[davideduardo]

I'd be interested to know how these tightly packed stations fare, analog coverage wise in the overlapping areas. Most modern car radios can probably pick the two apart easily, but what must it have been like back in the 70's, or with a modern cheap Chinese dollar store piece of junk?

Whether there is cochannel or adjacent close-by interference, studies of ratings results in multiple markets revealed that in home and at work listening (ranging from 75% of all listening in New York to 67% in LA) occurs 80% within the 70 dbu contour and 15% more inside the 64 dbu, based on quarter hours of listening (not cume). This applies to all kinds of top 100 markets, based on a sample of 15 markets from #1 to outside the top 75 over a period of years and including all listening in each market... hundreds of thousands of diaries per market in some of the larger cities.

If I were an owner or a manager, I'd still be concerned about fringe areas because we know most car radios perform a lot better ("lot" is a technical term of considerable weight. ) than home radios and our listeners may make excursions to the fringe of the market and if they can't get us, they come back home listening to some other station... so anything that touches our coverage is dangerous.

AM failed to see that cities were outgrowing their signals in the 50's and then did not see how new electrical devices were raising the noise floor. Now in a Market like LA, it takes near 15 mV/m to get any ratings response... making many stations that were once monsters into pygmies.

 

[local oscillator]

In my station's case, approximately 30% of listening is inside the 70 dBu contour, 60% between the 60 and 70 dBu contours, and 10% outside the 60dBu contour. So you can see why I am concerned by ANY new interference. My coverage area or "market" is made up of several small cities and towns; the population is dispersed, and there is no large core that is densely populated. Too many commenters on this board assume that all stations are nicely clustered in core markets, and therefore don't interfere with each other (due to four-channel spacing) and are all far enough away from adjacent markets so as to never be a problem. It just doesn't work that way, although I understand why folks who are in those neatly-defined core markets have that perspective.

 

[Play Freebird]

While you're right on target in most cases, I think you exaggerate a bit on this one. It's not "most" of Chester County that's in the interference zone; more like the northwestern 25% of the county is. WDAS-FM is dominant over most of the county with that portion being the exception where the two stations are more evenly matched. I agree that they are still spaced too closely, but the reality is that WIOV ends up being the loser in the majority of the county. You see, those FCC maps ignore topography and there are hills between West Chester/Exton/Coatesville and Reading. This blocks some of WIOV's signal in certain areas. As a result, WIOV's range into Chester County is exaggerated. Yes, I recall WIOV and WDAS-FM being about equal in the Lionville area - but travel a mile or two away (or down a hill) and the advantage quickly turns to 'DAS-FM.

Your point is valid -- WIOV's reach in this area does depend a lot on topography, but if WDAS increases digital power by 6 dB, I expect problems up the Schuylkill valley towards the northwest. In this case, I'm talking interference from WDAS to WIOV.

I should mention that WIOV's 2.8 kW booster in Reading (WIOV-FM1) might help overcome this interference in central Berks County, but it's a multipath generator in the outlying areas because the terrain doesn't isolate the two coverage areas sufficiently. Multipath + IBOC interference = even more noise. Fortunately, WIOV relies on the Lancaster home market for much of its income, but during band openings they probably get hit by co-channel interference from WAVA 105.1 near Washington.

 

[audioguy]

I was wondering why I was not hearing the annoying whine in the background while listening to WSQR on 1180 and then I discovered that AM 1200 had turned off their IBOC hissmaker. Probably temporary, but they sounded good in plain ole' mono!

 

[badjef]

Probably temporary, but they sounded good in plain ole' mono!

They would sound even better in Kahn ISB AM stereo.

Jeff in Sa-ra-so-ta!

 

[N1WVQ]

Even better in C-QUAM & the best in Magnavox! Kahn ISB sounded terrible.

 

[badjef]

Even better in C-QUAM & the best in Magnavox! Kahn ISB sounded terrible.

Can't prove it by me. I had both in the same radio.

Honk the horn in the car, and C-Quam would revert to mono.
I had ~110% coverage in Kahn stereo, I had about ~80% for C-Quam.

ISB was a "natural" stereo. C-Quam was mathmatic - same as FM.

Jeff in Sa-ra-so-ta!

 

[schmave]

WTVN/Columbus turned theirs off within the past hour ... unsure if it's maintenance. WLW's has been off for more than a week. All I know is I'm picking up stations on 620 and 690 in this region for the first time but did not have time to identify either this morning.