SKYWAVE Interference

[MarcB]

I really hate this time of year. Skywave intererence starts earlier and earlier. Yesterday I was driving from a restaurant in Southington, CT back to my apartment in Bristol, CT and at 1:50PM I could already hear someone interfering with WDRC 1360. I've driven that route many times around that time of day and never heard anyone interfering with WDRC before, that's why I believe it's skywave interference and not just a bad spot for the signal.

 

[schmave]

I used to listen to the Jim Rome Show on WKNR out of Cleveland when I lived in Columbus, and it was not uncommon to hear some cancellation at 1 or 2 in the afternoon.

 

[Icangelp]

On the other hand, I love it because I can DX while driving both to and from work, although we set our clocks back so it's no longer dark if I leave at normal end of work day.

 

[Tom Wells]

WJJG 1530 Elmhurst Illinois has been getting creamed in the afternoon by 1530 Cinncinati, Ohio for the last week.
I'm 15 miles away, and they're buried by skywave at 3 in the afternoon!

 

[rbrucecarter5]

KOA sideband interference is horrific here in Houston. It really jams KONO 860 on my drive home, WHAS 840 is unlistenable at night. And Houston is how far from Denver - 800 miles or so?! I am getting a taste of what folks get on the East coast on multiple frequencies ----

 

[charlestondxman]

We have a lot of skywave interference on several of my distant AMs in the Lowcountry. 980 AM, a station about 25 miles or so away, gets overrun by Washington from 4 pm on, when it's still light out till 5:30.

The graveyards also have interference from other stations on their frequency, and are inaudible maybe 15 miles out late in the afternoon here.

Even before DST, stations started coming in earlier and earlier. WPHT and WBAL came in for hours before sunset, and Charlotte stations like WBCN and WBT don't leave until an hour after sunrise, and come back 90 minutes before sunset.

Wow, KOA interference that far away? That's surprising.

 

[radiotower40]

WJJG 1530 Elmhurst Illinois has been getting creamed in the afternoon by 1530 Cinncinati, Ohio for the last week.
I'm 15 miles away, and they're buried by skywave at 3 in the afternoon!

Tom, you are correct about WJJG, I'm about 15 miles south of the towers and I can barely hear them by 3.
They also get buried some mornings until well after 8 AM. There are days when WCKY seems to be underneath them
virtually all day, during the winter months. The same holds true for AM 1470 WCFJ in Chicago Heights, which is
clobbered by WMBD in Peoria. As with WJJG, WMBD is underneath WCFJ most of the day.

 

[ddsparxx]

We have a lot of skywave interference on several of my distant AMs in the Lowcountry. 980 AM, a station about 25 miles or so away, gets overrun by Washington from 4 pm on, when it's still light out till 5:30.

The graveyards also have interference from other stations on their frequency, and are inaudible maybe 15 miles out late in the afternoon here.

Even before DST, stations started coming in earlier and earlier. WPHT and WBAL came in for hours before sunset, and Charlotte stations like WBCN and WBT don't leave until an hour after sunrise, and come back 90 minutes before sunset.

Wow, KOA interference that far away? That's surprising.

Last December around 4:30 PM that DC's 980 got overrun by WHAW 980 in Weston, WV; I heard it when driving from work in northern VA. Yesterday the DC area's WWGB 1030 (a daytimer) and Boston's WBZ were both heard at the same time.

 

[gar hi]

Just after 9:30 this morning with the sun well into the sky I was tuning the car radio and on 1700, I had a pretty goog signal from WJCC Miami Springs with KVNS fluttering way in the background.

 

[rbrucecarter5]

Wow, KOA interference that far away? That's surprising.

I confirmed it last night - I threw a null towards Denver, and WHAS cleared up completely.

The real shocker to me was WOR sideband noise when I was in Dallas. I'll have to try it here in Houston and see if it is the same story. WOR analog never makes it here with a lot of 710s closer. But the sidebands persist. I am grateful there is no initiative to raise AM sideband power like there is FM - given the persistence of those sidebands.

Another shocker to me was HD sidebands from Chicago (and other) stations , mid day, summer, in a rest stop West of Clayton NM. If I am ever back there, I am going to video it - a normal car radio, hissing sideband pairs from stations whose analog and even carriers are long since faded. Amazing stuff - it actually got me excited about DX possibilities for full digital AM. If the sidebands are that persistent even at low power levels, complete digital could revolutionize the AM band, allowing daytime coast to coast full digital reception at a fraction of the power required for analog. If the FCC was smart enough to intelligently re-shuffle allocations nationwide to make the scheme work ---

 

[BobOnTheJob]

If there's a bright side to this AM IBOC mess, it's that they actually did narrow it up. I was at the NAB in Vegas in the 90's & they had an AM station set up in HD only. It sounded better than FM, the signal was robust, even through tunnels & bridges. Catch was that on an analog car radio, it took up 3 channels above & below the licensed frequency (I want to say it was on 1640). Now if they could just get it contained totally within +/- 10khz...

 

[formerjock]

I love this time of year for DX'ing. Yesterday between 230p and 400p eastern driving in east tn:
WLOR 1550 Huntsville, AL like a local, WLS 890 reasonably strong already. WBBR 1130 NY fairly strong, WGVN 1580 Georgetown,KY, WAGL 1560 Lancaster, SC plus WCKY 1530 like a local. Winter can be fun for DX'ers!

 

[Len14043]

Another shocker to me was HD sidebands from Chicago (and other) stations , mid day, summer, in a rest stop West of Clayton NM. If I am ever back there, I am going to video it - a normal car radio, hissing sideband pairs from stations whose analog and even carriers are long since faded. Amazing stuff - it actually got me excited about DX possibilities for full digital AM. If the sidebands are that persistent even at low power levels, complete digital could revolutionize the AM band, allowing daytime coast to coast full digital reception at a fraction of the power required for analog. If the FCC was smart enough to intelligently re-shuffle allocations nationwide to make the scheme work ---

That is one big reason I hope FM IBOC succeeds. Perhaps successful FM stations will make a leap and simulcast AM sister stations in the all-digital mode, bypassing the unworkable hybrid system.

 

[BobOnTheJob]

Another shocker to me was HD sidebands from Chicago (and other) stations , mid day, summer, in a rest stop West of Clayton NM. If I am ever back there, I am going to video it - a normal car radio, hissing sideband pairs from stations whose analog and even carriers are long since faded. Amazing stuff - it actually got me excited about DX possibilities for full digital AM. If the sidebands are that persistent even at low power levels, complete digital could revolutionize the AM band, allowing daytime coast to coast full digital reception at a fraction of the power required for analog. If the FCC was smart enough to intelligently re-shuffle allocations nationwide to make the scheme work ---

That is one big reason I hope FM IBOC succeeds. Perhaps successful FM stations will make a leap and simulcast AM sister stations in the all-digital mode, bypassing the unworkable hybrid system.

Is this even currently allowed? Next question is this...Is all digital mode TOTALLY contained within the +/- 100khz channel like analog FM is? If it's as broad as hybrid mode, it will be even worse than hybrid. At least the analog signal still functions with noise. Two IBOC's eating each other equals silence until you get a quite strong desired to undesired ratio.

 

[Len14043]

Bob,
I apologize for not being clear in my post. I was responding to Bruce's post about the dxing possibilities of all-digital AM. I meant to say that I hope FM IBOC becomes a success to the point to where their company might try simulcasting one of their AM stations in the AM all-digital mode. However, for that to be possible, FM would have to reach critical mass, and HD radios would need to include AM.

 

[Tom Wells]

Bob,
I apologize for not being clear in my post. I was responding to Bruce's post about the dxing possibilities of all-digital AM. I meant to say that I hope FM IBOC becomes a success to the point to where their company might try simulcasting one of their AM stations in the AM all-digital mode. However, for that to be possible, FM would have to reach critical mass, and HD radios would need to include AM.

And to work effectively at MW, it would also need about 3 times the current bandwidth for data "triple-dundancy".
The (data rate) x ( modulation carrier resolution ) leaves many "bits" falling into a carrier zero-crossing, where they simply do not exist
to BE decoded. AM, per se, is NOT the reason digital works so poorly, it is the frequency the AM band resides in.

If ibiquity really wanted this to fly, they'd have stood up to the NAB and expalined to them, as an adult must explain to a child, that certain things don't work. "No, you can't jump off the roof with a bedsheet for a parachute.
You can't jump off the roof with a real parachute. It won't work. You'll break something."

No matter how much you might like to do something, the inconvenient laws of physics will still be there.

 

[DavidEduardo]

Is this even currently allowed?

Quite a few local AMs are rebroadcast on FM signals. KNX in LA is on an HD of KTWV, for example. And it is permitted, too, just as AM FM simulcasting is permitted again and so is FM FM and even FM FM FM simulcasting in the same market.

 

[radioman148]

WLS-AM is carried on WLS-FMs HD2. Also, WBBM-AM is on one of the CBS HD2 FMs in Chicago.

 

[gar hi]

WLS used to have such a good signal down here back in their top 40 days.

Now, it can barely be heard a lot of the time and the Spanish station now also on 890 isn't really too strong.

 

[BRNout]

Is this even currently allowed?

Quite a few local AMs are rebroadcast on FM signals. KNX in LA is on an HD of KTWV, for example. And it is permitted, too, just as AM FM simulcasting is permitted again and so is FM FM and even FM FM FM simulcasting in the same market.

Absolutely!

In the Chicago area, there are a couple of examples of simulcasting that are even more interesting than the airing of a sister station on an HD2. For example, we have the liberal, er, 'progressive' talk formatted WCPT 820 Willow Spgs./Chicago that's simulcast on WCPY 92.5 DeKalb, IL, WCPT-FM 92.7 Arlington Heights, IL and WCPQ 99.9 Park Forest, IL. That's an AM-FM-FM-FM!

Not to mention: WVIX 93.5 Lemont, IL/WVIV 103.1 Highland Park, IL (FM FM); WWDV 96.9 Zion, IL/WDRV 97.1 Chicago (FM FM); and, WSRB 106.3 Lansing, IL/WYRB 106.3 Genoa, IL (FM FM on the same frequency). The WWDV/WDRV simulcast carries '97.1 The Drive' well into the Milwaukee/Racine/Kenosha, WI market. Each example is a 100% simulcast with no local break-aways. All were done to increase the geographic reach of the station/format in question.

More complex, but apparently still allowed, are the new simulcasts that are bringing AM signals from one market onto FM HD2's in another. Like WFAN New York onto FM subs in Florida.