HFU HF Underground
General Category => General Radio Discussion => Topic started by: NJQA on November 23, 2019, 1109 UTC
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https://radioinsight.com/headlines/181941/fcc-approves-digital-am/
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There goes the MW band. WWFD is semi local to me, and trashes both adjacent channels. Sigh.
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the key language here is 'voluntary'. There is no mandate to go to digital, and in my view for any station that would be suicide. 95% of the stations out there are running at low power, messed up arrays, bad audio, etc. They don't have the money to fix what they have and no one is going to be forming a line at ibequity's door. I think this is the last gasp of digital on AM here.
+-RH
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The local CC right wing AM talk station has a CP for an FM translator. I wonder if they are planning to go digital? That will surely confuse all their old listeners. 8)
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Won't be much change to the band. Not many stations on the AM band use IBOC HD now. I don't see much change happening.
A handful of stations, in major metros, at best, may take the option.
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I don't see much change happening.
good :)
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I think this is the last gasp of digital on AM here.
let's hope ;)
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the key language here is 'voluntary'. There is no mandate to go to digital, and in my view for any station that would be suicide.
Yes but all the puppets will goto it anyway.. All the ones running IBOC will probably be the first.....
I wont listen to them if they do that so if they wanna lose listeners let them.....
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the key language here is 'voluntary'. There is no mandate to go to digital, and in my view for any station that would be suicide.
Yes but all the puppets will goto it anyway.. All the ones running IBOC will probably be the first.....
I wont listen to them if they do that so if they wanna lose listeners let them.....
The ones who were running IBOC probably gave up on it for valid reasons, one of them being that the equipment finally broke down and/or wasn't cost effective.
If a local station happens to go all-digital I'll listen -- there are several stations that used IBOC in my metro, and they had decent formats (sports, South Asian, classic country, etc.). I'm not holding my breath for them to turn the digital on, though (see my previous sentence about equipment breakdown and cost effectiveness).
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I just realized, Digital AM (Amplitude Modulation) is an oxymoron.
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I just realized, Digital AM (Amplitude Modulation) is an oxymoron.
Well, not really, the present digital format is hybrid so it's both digital and AM.
Of course, pure digital is another matter.
Although IMHO none of it belongs on the AM band.
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the key language here is 'voluntary'. There is no mandate to go to digital, and in my view for any station that would be suicide.
Yes but all the puppets will goto it anyway.. All the ones running IBOC will probably be the first.....
I wont listen to them if they do that so if they wanna lose listeners let them.....
The major groups had to roll out a set number of station for the initial HD rollout, and as such were contractually bound for a period of time to keep them running. Apparently the contract has run out. The early HD stuff was not very reliable, using industrial PC's running custom OS to generate the HD waveforms. The newer gear is a lot more reliable, but apparently no one wants to spend the money on something that nets them no return on their investment. The only innovations making any headway in AM these days are those that save money or power, hence why MDCL is a thing now, particularly on the 50KW flame throwers where the power savings can be very noticeable.
+-RH
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I just realized, Digital AM (Amplitude Modulation) is an oxymoron.
It's correct I think. It's the amplitude of the carrier that is modulated with digital information.
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I spent a little time this week listening to WWFD while driving around. I am in the lower Southern edge of WWFD’s fringe area according to this:
https://radio-locator.com/cgi-bin/pat?call=WWFD&service=AM&h=D
My receiver was the factory radio in my 2017 pickup.
First of all, I was surprised at how well it worked. I expected dropouts (and there were plenty) but they were far fewer than I expected. As is normal with digital radio, everything was either perfect, or non existent. When the signal was there, sound quality was markedly better than the normal AM radio I listen to. In fact it sounded much better than our local 22kW station.
Looking at the spectrum on my SDR at home, I realized that this is a much better “neighbor” than stations running the hybrid analog/digital mode. WWFD’s entire carrier is contained +/- 5 kHz of their assigned frequency. The analog stations have their digital carriers on the adjacent channels. Granted, their digital carriers are 30 dB below their carrier power, but they do interfere with stations on those adjacent channels.
So I have mixed feelings about this. As a DXer, I abhor this as the digital carrier effectively wipes out a channel. You can’t hear anything through this. Last night I saw three strong hybrid stations that effectively wiped out the channels above and below them - and that was with them running the digital signal at -30 dBc. A digital carrier will lock up a channel for DXing purposes. You can’t hear anything thru it. It is a white noise jammer.
But as a consumer, I would listen to digital AM radio for local listening. The sound quality is significantly better. And whatever range problems the current hybrid system has will get much better if they can up the digital power by 30 dB! WWFD was “listenable” in my fringe area-I imagine it is very usable where Chris lives.
This could gain steam.
The bright side is that if you replaced a local hybrid station with a pure digital station, you will probably get the adjacent channels back for DXing.
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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. AM sounded clearer & easier to listen to. The digital signal was annoying and had dropouts, even though they're a 50kW station and I was stationary a mere 15 miles away.
They have since turned off the hybrid and are on AM only. It sounds even better in AM now, since they're a bit wider in bandwidth and not that stupid 5 kHz audio (10 kHz RF) bandwidth which makes it sound muddled.
No locals on MW IBOC hybrid around here these days, so can't do any further tests. Do occasionally get the IBOC jamming from DX stations, but usually those are not stable enough for the receiver to lock onto for more than a few seconds.
As a listener, I found nothing useful with IBOC hybrid. It seems to be a solution in search of a problem.
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.
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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.
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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.
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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))
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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.
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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.
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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 (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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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 (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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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?
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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.
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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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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"!!
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Antenna phaser system needs to be a closed loop of coaxial transsmision line with a reject port. Like a ring hybrid. 8)
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...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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...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.