HARDER, LONGER, DEEPER

[stacker]

No, I'm not promoting Extenze.

There has been a ton of talk about AM IBOC adjacent channel interference. But, I think IBOC has unleashed a bunch more trouble for co-channel (same frequency) stations.

I've noticed that critical hours sky wave interference appears to have gotten worse if the co-channel station is running IBOC.

You've probably heard the slow rolling effect of near sunset sky wave fades. When one of the stations is running IBOC, the fade seems exaggerated since you hear not only the analog sidebands fading, but all the digital carriers wiping across the "eye" of the receiver. It's not pleasant for the listener.

Of course, during fading all bets are off since everything is non-linear. Adding the IBOC hiss to the mix appears to have resulted in another opportunity for IBOC interference.

I'm not talking about a problem that exists in fringe areas. I've noticed this phenomenon where the victim is delivering 10 mV.

Anyone else observing this?

 

[audioguy]

I have heard that effect too. It's as though the tonality of the noise swishes and sways in the background. Do you remember those LORAN stations that transmitted in the lower SW bands? Sounds a bit like that to me.

Personally I find that I can never get rid of the IBOC noise entirely, even on 50 kW locals like WBBM in the middle of the day. It's fatiguing and I refuse to listen to it for more than a few moments. Unfortunately CBS is clinging desperately to this flawed technology and they'll probably be the last ones to turn it off.

 

[8638]

I have heard that effect too. It's as though the tonality of the noise swishes and sways in the background. Do you remember those LORAN stations that transmitted in the lower SW bands? Sounds a bit like that to me.

Personally I find that I can never get rid of the IBOC noise entirely, even on 50 kW locals like WBBM in the middle of the day. It's fatiguing and I refuse to listen to it for more than a few moments. Unfortunately CBS is clinging desperately to this flawed technology and they'll probably be the last ones to turn it off.

It makes WOR New York sound like crap on anything analog. And it doesn't consistently lock HD on my Sony, even in daytime (70 miles from TX). I wish they'd turn it off.

 

[stacker]

have heard that effect too. It's as though the tonality of the noise swishes and sways in the background. Do you remember those LORAN stations that transmitted in the lower SW bands? Sounds a bit like that to me.

Yep. As the fade goes through it's cycle, you can hear a big long "swoosh" as the sidebands fade.

 

[tomservo]

I haven't heard it, but chances are the few AM's I might listen to during critical hours may not have co-channel HD stations close enough to cause problems.

 

[stacker]

chances are the few AM's I might listen to during critical hours may not have co-channel HD stations close enough to cause problems.

Probably so Zach. Since this is a skywave related issue during the late and early daytime hours, it can present itself hundreds of miles from the co-channel HD station. When it occurs, it's very destructive to the local non-HD audience.

HD AM's keep dropping like leaves on a tree. It's time to just shut it off and let the rest of us get on with the business of broadcasting.

 

[JohnnyElectron]

Yep, there is a list online of all the AM stations, and those that have dropped HD. Several are "only off temporarily" - yea, right.

BTW, the Subject line of this thread sounds like somebody was watching a porno movie before they posted about skywave IBOC interference!