HD Interference Case #174 (FM)

[audiophile.]

In the HD Interference Case #1 (FM) I documented first adjacent interference in cases 1 to 173 ( http://gullfoss2.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6516753033 ).

This begins the second part as promised. In this case it is HD interference from a second adjacent FM class "A" to a Class "B". When WRDZ on 98.3 went digital it began transmitting on WGNR's (97.9) first adjacent - specifically 98.102 to 98.177 to MHz. FCC rules specify an interference ratio -6 dB for first adjacent transmissions. WGNR's protected contour is 54 dBu, therefor the interference contour from WRDZ is 48 dBu. I used one-half of WRDZ maximum digital power (lower side bands only) which amounts to the equivalent 15 watts from the authorized height.

WGNR's 54 dBu is drawn as a green circle. WRDZ 48 dBu interference contour is drawn in yellow.
Click here >>> http://s07.picshome.com/26f/wrdz-wgnr(1).jpg <<<

As you can seen by the population spray overlay there are thousands of people potentially recieving interference from WRDZ inside the protected contour of WGNR! Each white or yellow "++" equal 1000 people or more.

PS WGNR / WRDZ is not super powered or anything like that. The normal contour 54/94 dBu ratios just kiss slightly...

 

[SUPERCASTER]

HD Radio is incompatible with current channel assignments and should not get final approval. The HD Radio experiment should cease.
The ex parte lawyer/lobbyist FCC fileing of July 5, 2006 proposing a new, more relaxed FM mask and a change in measurement methods from peak to average will multiply interference causing even more severe problems.

 

[1q2w3e]

In the HD Interference Case #1 (FM) I documented first adjacent interference in cases 1 to 173 ( http://gullfoss2.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6516753033 ).

This begins the second part as promised. In this case it is HD interference from a second adjacent FM class "A" to a Class "B". When WRDZ on 98.3 went digital it began transmitting on WGNR's (97.9) first adjacent - specifically 98.102 to 98.177 to MHz. FCC rules specify an interference ratio -6 dB for first adjacent transmissions. WGNR's protected contour is 54 dBu, therefor the interference contour from WRDZ is 48 dBu. I used one-half of WRDZ maximum digital power (lower side bands only) which amounts to the equivalent 15 watts from the authorized height.

WGNR's 54 dBu is drawn as a green circle. WRDZ 48 dBu interference contour is drawn in yellow.
Click here >>> http://s07.picshome.com/26f/wrdz-wgnr(1).jpg <<<

As you can seen by the population spray overlay there are thousands of people potentially recieving interference from WRDZ inside the protected contour of WGNR! Each white or yellow "++" equal 1000 people or more.

PS WGNR / WRDZ is not super powered or anything like that. The normal contour 54/94 dBu ratios just kiss slightly...

Have you actually been to Indy to see if ther really is any interference? The key word is POTENTIAL. I am driving through there in a few days and would be more than happy to check it out. If the contours kiss as you say there should be little or no interference issues.

That being said, it appears to be a close spacing issue where one or the other has to put up with the spacing. More than likely WRDZ-FM.

 

[IBOCRocks]

In the HD Interference Case #1 (FM) I documented first adjacent interference in cases 1 to 173 ( http://gullfoss2.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6516753033 ).

This begins the second part as promised. In this case it is HD interference from a second adjacent FM class "A" to a Class "B". When WRDZ on 98.3 went digital it began transmitting on WGNR's (97.9) first adjacent - specifically 98.102 to 98.177 to MHz. FCC rules specify an interference ratio -6 dB for first adjacent transmissions. WGNR's protected contour is 54 dBu, therefor the interference contour from WRDZ is 48 dBu. I used one-half of WRDZ maximum digital power (lower side bands only) which amounts to the equivalent 15 watts from the authorized height.

WGNR's 54 dBu is drawn as a green circle. WRDZ 48 dBu interference contour is drawn in yellow.
Click here >>> http://s07.picshome.com/26f/wrdz-wgnr(1).jpg <<<

As you can seen by the population spray overlay there are thousands of people potentially recieving interference from WRDZ inside the protected contour of WGNR! Each white or yellow "++" equal 1000 people or more.

PS WGNR / WRDZ is not super powered or anything like that. The normal contour 54/94 dBu ratios just kiss slightly...

Have you actually been to Indy to see if ther really is any interference? The key word is POTENTIAL. I am driving through there in a few days and would be more than happy to check it out. If the contours kiss as you say there should be little or no interference issues.

That being said, it appears to be a close spacing issue where one or the other has to put up with the spacing. More than likely WRDZ-FM.

It makes interesting reading, but really there needs to be more than just a blanket "here's a list" situation. I'm thinking that the Commission will require that these be handled on a case-by-case basis. The bottom line is that this covers a handful of "superpower" FM's, and not IBOC as a whole. It could simply requre ratcheting down the HD carrier to what the Commission feels is an acceptable level. I think in most cases these "Superpowers" aren't going to need to cover their entire contour with HD, as their trade areas fall mainly inside their primary contours.

Purely conjecture on my part, however.

 

[audiophile.]

WRDZ-FM has a digital notification, so I assume it is on.
http://svartifoss2.fcc.gov/cgi-bin/ws.exe/prod/cdbs/pubacc/prod/app_det.pl?Application_id=1035116

WRDZ is a 3 kw @ 300' Class "A" that meets the 40 mile distance separation requirements prior to docket 80-90. On contour basis the 94 / 54 do kiss de-minimusly. On an analog basis WGNR / WRDZ protect each other quite well.

On the IBOC side that is different story! Click here >>> http://s07.picshome.com/26f/wrdz-wgnr(1).jpg <<<

1q2w3e if want, knock yourself on this one! If you have spectrum analyzer it may helpful to see verify the digital level of WRDZ-FM. It would be interesting to compare a few receivers too...

 

[1q2w3e]

WRDZ-FM has a digital notification, so I assume it is on.
http://svartifoss2.fcc.gov/cgi-bin/ws.exe/prod/cdbs/pubacc/prod/app_det.pl?Application_id=1035116

WRDZ is a 3 kw @ 300' Class "A" that meets the 40 mile distance separation requirements prior to docket 80-90. On contour basis the 94 / 54 do kiss de-minimusly. On an analog basis WGNR / WRDZ protect each other quite well.

On the IBOC side that is different story! Click here >>> http://s07.picshome.com/26f/wrdz-wgnr(1).jpg <<<

1q2w3e if want, knock yourself on this one! If you have spectrum analyzer it may helpful to see verify the digital level of WRDZ-FM. It would be interesting to compare a few receivers too...

I have one too. IF (and that is a big IF) I have the time to check it out while driving (I will be trying to put on 1300 miles that day) I will stop and take some readings. If not I will have to rely on my good old radios. Sorry. But I will get the chance to get back there in a month. This ought to be interesting. but I am pretty sure of the outcome. I put up a station with just about the same specs as WGNR and am quite familiar with what will happen.

 

[SaynotoIB0C]

How could I think digital interfered with analog, no way, the hash sounds like great programming on my polk i-sonic

 

[1q2w3e]

OOPS I may have swapped the station that is running HD. Is WRDZ notified with HD? I was assuming the other (50kW) was running it. Either way, it ought to be interesting.

 

[audiophile.]

Yes it's WRDZ that is running digital.

IF WGNR went IBOC it would probably hurt WRDZ but not within the protected contour.

 

[audiophile.]

If IBOC increases from peak to average, could expect this scenario to get worse?

 

[SUPERCASTER]

If IBOC increases from peak to average, could expect this scenario to get worse?

Some say 13 db greater interference, plus the proposed new, wider, stronger, saddlebag spread added to the adjacent channels.

 

[1q2w3e]

SOLVED!! Re: HD Interference Case #174 (FM)

In the HD Interference Case #1 (FM) I documented first adjacent interference in cases 1 to 173 ( http://gullfoss2.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6516753033 ).

This begins the second part as promised. In this case it is HD interference from a second adjacent FM class "A" to a Class "B". When WRDZ on 98.3 went digital it began transmitting on WGNR's (97.9) first adjacent - specifically 98.102 to 98.177 to MHz. FCC rules specify an interference ratio -6 dB for first adjacent transmissions. WGNR's protected contour is 54 dBu, therefor the interference contour from WRDZ is 48 dBu. I used one-half of WRDZ maximum digital power (lower side bands only) which amounts to the equivalent 15 watts from the authorized height.

WGNR's 54 dBu is drawn as a green circle. WRDZ 48 dBu interference contour is drawn in yellow.
Click here >>> http://s07.picshome.com/26f/wrdz-wgnr(1).jpg <<<

As you can seen by the population spray overlay there are thousands of people potentially recieving interference from WRDZ inside the protected contour of WGNR! Each white or yellow "++" equal 1000 people or more.

PS WGNR / WRDZ is not super powered or anything like that. The normal contour 54/94 dBu ratios just kiss slightly...

I owed a response to this post.

I drove through Indy yesterday (specifically the North West side -- the side that was suggested would be the most problematic). WGNR was not interefered with AT ALL (as a matter of fact it was stronger than I had expected). WRDZ was full in HD (though their audio processing sucked in HD). WGNR was so clean that I didnt even see the need to pull out the spectrum analyzer. WRDZ held its HD until the far eastern side of the city, then started getting a little spotty (but that could be because I was close to the antenna farm in the city)

So may I suggest that the info provided was more hopeful than fact in regards to interference, asn there was NO, NONE, ZIP, NADA interference.

If you want a real test of HD radio.. look at 97.1 WDRV (Chicago) and 96.9 WWDV (Zion). These stations simulcast and are about 40 miles apart. Even though they are first adjacents Their HD signals do NOT interfere with their analog signals. I drove through all of Chicago yesterday and took a good amount of time to observe these two stations. Each station is slightly directional away from each other, but at no time was the analog signal interfered with by the digital carriers. This is not "potential" interference, "potential maps"... it is real life monitoring.

 

[audiophile.]

It's the Southwest side of town that will have problems slightly inside of the circle specifically. On the northwest side there would be no problems all!

I know your time was limited, so thanks for the report, but I guess at some point I'll need to check this out myself in further detail.

I have found first-adjacents are generally better protected on a contour basis.

I do have a case of actual inteference but for legal reasons my boss won't let me post it here.

 

[1q2w3e]

It's the Southwest side of town that will have problems slightly inside of the circle specifically. On the northwest side there would be no problems all!

I know your time was limited, so thanks for the report, but I guess at some point I'll need to check this out myself in further detail.

I have found first-adjacents are generally better protected on a contour basis.

I do have a case of actual inteference but for legal reasons my boss won't let me post it here.

Well I took the 465 on the west side to (I think) 70 into downtown. Right into the area listed on the JPG you posted. I was in the area and didnt see a problem at all.

Feel free to private message me the details of the other and we can discuss it off line if you would like.

 

[Chuck]

Well I took the 465 on the west side to (I think) 70 into downtown. Right into the area listed on the JPG you posted. I was in the area and didnt see a problem at all.

Feel free to private message me the details of the other and we can discuss it off line if you would like.

Were you using an analog radio, or one with HD capabilities? I'm just wondering if maybe it works fine on HD radios, and some analog radios exhibit problems? Or then again, maybe they don't. Enquiring minds want to know.

 

[audiophile.]

quote author=IBOCRocks link=topic=48042.msg332183#msg332183 date=1158766887]

"When did this happen? iBiquity did the research, it was peer-reviewed, tested, and accepted. The NRSC committee and the FCC looked at it and approved it for testing. How did iBiquity write their own rules? I'lll concede that IBOC on AM is an issue, but I 100% disagree that FM is a problem. I've travelled all over, and have not had any reception issues, nor have we heard of any widespread interference complaints. Again, the coverage isn't poor - there are lots of people who pull out "predicted" coverage maps, but in the middle of the country, a 50Kw FM running IBOC can easily cover 30+ miles in HD/HD2. Receiver design is the key...you don't need to use "brute force" to get a clean signal...you need just enough to decode."

Becasue the FCC did not even consider alternative working technologies, as DRM, which doesn't have the serious issues, as with IBOC. There are many testimonials to IBOC FM interference.

There are many testimonials, most of which are anecdotal at the moment. Until there is some solid proof, and some rulings to back it up, it's a "he said, she said" proposition.

The FCC is free to consider or not consider anything. At the time IBOC appeared to them to be the superior technology. Who knows, they may still feel that way.
[/quote]

Again, Here you go IBOCRocks...

 

[IBOCRocks]

quote author=IBOCRocks link=topic=48042.msg332183#msg332183 date=1158766887]

"When did this happen? iBiquity did the research, it was peer-reviewed, tested, and accepted. The NRSC committee and the FCC looked at it and approved it for testing. How did iBiquity write their own rules? I'lll concede that IBOC on AM is an issue, but I 100% disagree that FM is a problem. I've travelled all over, and have not had any reception issues, nor have we heard of any widespread interference complaints. Again, the coverage isn't poor - there are lots of people who pull out "predicted" coverage maps, but in the middle of the country, a 50Kw FM running IBOC can easily cover 30+ miles in HD/HD2. Receiver design is the key...you don't need to use "brute force" to get a clean signal...you need just enough to decode."

Becasue the FCC did not even consider alternative working technologies, as DRM, which doesn't have the serious issues, as with IBOC. There are many testimonials to IBOC FM interference.

There are many testimonials, most of which are anecdotal at the moment. Until there is some solid proof, and some rulings to back it up, it's a "he said, she said" proposition.

The FCC is free to consider or not consider anything. At the time IBOC appeared to them to be the superior technology. Who knows, they may still feel that way.

Again, Here you go IBOCRocks...
[/quote]

And one more time, not really...