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Author Topic: FCC approves all digital AM  (Read 560 times)

Offline pinto vortando

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Re: FCC approves all digital AM
« Reply #15 on: November 29, 2019, 1108 UTC »

If the problem is noise on the MW band, then the FCC can do something about that. RFI is bad these days- unintentional radiators from crappy electronics are all over the place. They not only radiate the signals, but also put it on the power lines which also distribute it over wide areas. Dirty power lines are very common here.

Bingo !
Fix the actual problem.

Ban the crappy offshore electronics.

The power lines not only re-radiate the crap but also contribute to the radio pollution themselves
as the lines are ill-maintained.
Das Radiobunker somewhere in Michigan

Offline ChrisSmolinski

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Re: FCC approves all digital AM
« Reply #16 on: November 29, 2019, 1357 UTC »

If the problem is noise on the MW band, then the FCC can do something about that. RFI is bad these days- unintentional radiators from crappy electronics are all over the place. They not only radiate the signals, but also put it on the power lines which also distribute it over wide areas. Dirty power lines are very common here.

Bingo !
Fix the actual problem.

Ban the crappy offshore electronics.

The power lines not only re-radiate the crap but also contribute to the radio pollution themselves
as the lines are ill-maintained.

Spend tends of billions of dollars to fix the MW band that no one listens to? Not going to happen.
Chris Smolinski
Westminster, MD
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Offline Dude111

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FCC approves all digital AM
« Reply #17 on: November 29, 2019, 1742 UTC »
Quote from: skeezix
A bunch of years ago when WCCO transmitted IBOC hybrid, I tried it on a receiver at home. I'm 15 miles away and it sounded like a crappy Internet stream.

Thats my opinion..... It sounds like crap...... I prefer listening to the analogue carrier!! (It sounds better (Not as sterile,etc))

Offline skeezix

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Re: FCC approves all digital AM
« Reply #18 on: November 30, 2019, 0003 UTC »

If the problem is noise on the MW band, then the FCC can do something about that. RFI is bad these days- unintentional radiators from crappy electronics are all over the place. They not only radiate the signals, but also put it on the power lines which also distribute it over wide areas. Dirty power lines are very common here.

Bingo !
Fix the actual problem.

Ban the crappy offshore electronics.

The power lines not only re-radiate the crap but also contribute to the radio pollution themselves
as the lines are ill-maintained.

Spend tends of billions of dollars to fix the MW band that no one listens to? Not going to happen.

Or just enforce Part 15.

You're correct, they won't do that.


Minneapolis, MN

Offline ChrisSmolinski

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Re: FCC approves all digital AM
« Reply #19 on: November 30, 2019, 1326 UTC »

If the problem is noise on the MW band, then the FCC can do something about that. RFI is bad these days- unintentional radiators from crappy electronics are all over the place. They not only radiate the signals, but also put it on the power lines which also distribute it over wide areas. Dirty power lines are very common here.

Bingo !
Fix the actual problem.

Ban the crappy offshore electronics.

The power lines not only re-radiate the crap but also contribute to the radio pollution themselves
as the lines are ill-maintained.

Spend tends of billions of dollars to fix the MW band that no one listens to? Not going to happen.

Or just enforce Part 15.

You're correct, they won't do that.

It's unenforceable at this point.  You can't take away everyone's stuff.
Chris Smolinski
Westminster, MD
eQSLs appreciated! csmolinski@blackcatsystems.com
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Offline chanito

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Re: FCC approves all digital AM
« Reply #20 on: December 03, 2019, 0324 UTC »
Take a cue from India and China. The car radios already exist:
https://www.radioworld.com/news-and-business/india-drm-receivers-find-place-in-cars


DRM30 works with existing feedline and antennas, and with relatively modern existing transmitters, so no need to retool the entire RF chain.



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Offline redhat

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Re: FCC approves all digital AM
« Reply #21 on: December 03, 2019, 0338 UTC »
Take a cue from India and China. The car radios already exist:
https://www.radioworld.com/news-and-business/india-drm-receivers-find-place-in-cars


DRM30 works with existing feedline and antennas, and with relatively modern existing transmitters, so no need to retool the entire RF chain.

Its not usually that simple.  Any digital mode requires a reasonably flat group delay response across the occupied bandwidth.  older AM directional systems often had very poor bandwidth and need a complete overhaul to pass the digital signals of ANY type.  We first started learning about group delay problems in existing arrays during the AM stereo rollout of the early 80's.  HD/DRM is best implemented on simple, non-directional antenna systems.

+-RH
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Offline KaySeeks

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Re: FCC approves all digital AM
« Reply #22 on: December 03, 2019, 1935 UTC »
Its not usually that simple.  Any digital mode requires a reasonably flat group delay response across the occupied bandwidth.  older AM directional systems often had very poor bandwidth and need a complete overhaul to pass the digital signals of ANY type.

Can they implement equalization or "pre-distortion" to mitigate any of this? Probably wouldn't fix all cases but perhaps some?
« Last Edit: December 03, 2019, 1940 UTC by KaySeeks »
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Offline redhat

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Re: FCC approves all digital AM
« Reply #23 on: December 03, 2019, 1956 UTC »
New adaptive precorrection can deal with minor problems to some degree, but large equalization shifts require more transmitter headroom which may not be available depending on required TPO and transmitter rating.  Also keep in mind with directionals especially, the radiated response in the nulls may be cause loss of receive due to group delay and amplitude response issues.  In the analog days, the nulls may just sound funny, but still be listenable.

A friend of mine used to care for a 3 tower array built in the late 40's.  The transmission line to the towers was open wire coax (5 wire).  The array was so narrow, they had to cut the audio down to 6 KHz to keep the new transmitter from tripping off on VSWR.  The array has since been overhauled with new transmission line and ATU's.

+-RH
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Offline Radio Boogie

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Re: FCC approves all digital AM
« Reply #24 on: December 04, 2019, 0418 UTC »
Indeed, Redhat! I worked at several AM stations with old arrays that were fine with the old tube transmitters, but had problems when upgrading to solid state transmitters, *especially* those with pulse Width modulators in them. And since a vast majority of AM stations have to reduce power at sunset, if not change their patterns completely, this compounded the issue greatlly since some stations actually had to switch transmitters and tower sites. So, in those cases there are even more acres of steel and copper to try to make act "friendly" to newer gear. Some AM stereo sites had to roll off at around 7kHz to keep these newer rigs from shutting off. Many had to give up asymmetrical modulation as well. WKNX in Saginaw, MI was one such beast, WTAC in Flint another. WTAC finally moved to a new site back around the turn of the century, and ended up having to modify their license to cover at 443 watts instead of the 1kW because, even though the new towers were broadband enough, the TX still had major issues with the AM stereo.

With all the problems some AM's have just doing analog, full digital will be the gun that they shot their balls off with should they attempt that. But, honestly, none of these problem sites I've known over the years even bothered to try HD, so...
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Offline Radio Boogie

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Re: FCC approves all digital AM
« Reply #25 on: December 04, 2019, 0430 UTC »
Or just enforce Part 15.

You're correct, they won't do that.

Well, only if you're *broadcasting* over you're allotted nanowatts, LOL!

And, for that matter, they don't hardly bother to enforce Part 73 rules anymore. It takes like an F Bomb in drive time or blatant interference with other stations to get action anymore... I guess with IBOC, AM "interference" is considered standard engineering practice now. Um... wasn't IBOC supposed to be approved to fight interference??? LOL!

Indeed, a solution to a yet to be found "problem", so it created it's OWN!

And, in fact, I drove by a station I used to engineer not long ago, and ALL THREE 367' towers had not a single working beacon, and only the middle tower had the 75' obstruction lamps lit... nothing above those were lit, and it's in the direct approach to the airport! In fact, it's listed on the FAA maps as a LANDMARK for VFR. How does Cumulus get away with this crap? And that is only ONE of their tower lighting issues in this market.

A buddy of mine said, "if Cumulus was in fast food, "Food Poisoning" would be top item on the menu"!!
« Last Edit: December 04, 2019, 0437 UTC by Radio Boogie »
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Online JimIO

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Re: FCC approves all digital AM
« Reply #26 on: December 04, 2019, 1840 UTC »
Antenna phaser system needs to be a closed loop of coaxial transsmision line with a reject port. Like a ring hybrid.    8)

~

Offline redhat

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Re: FCC approves all digital AM
« Reply #27 on: December 04, 2019, 2002 UTC »
...in fact, I drove by a station I used to engineer not long ago, and ALL THREE 367' towers had not a single working beacon, and only the middle tower had the 75' obstruction lamps lit... nothing above those were lit, and it's in the direct approach to the airport! In fact, it's listed on the FAA maps as a LANDMARK for VFR. How does Cumulus get away with this crap? And that is only ONE of their tower lighting issues in this market.

I'm all for minding my own business, but that is a life safety issue.  Call the FAA.

+-RH
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Offline skeezix

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Re: FCC approves all digital AM
« Reply #28 on: December 05, 2019, 0135 UTC »
...in fact, I drove by a station I used to engineer not long ago, and ALL THREE 367' towers had not a single working beacon, and only the middle tower had the 75' obstruction lamps lit... nothing above those were lit, and it's in the direct approach to the airport! In fact, it's listed on the FAA maps as a LANDMARK for VFR. How does Cumulus get away with this crap? And that is only ONE of their tower lighting issues in this market.

I'm all for minding my own business, but that is a life safety issue.  Call the FAA.

+-RH

Have to agree.

Found the station's towers on the chart and checked the NOTAMs for the nearby airport and there is no notice.
Minneapolis, MN