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Author Topic: bcbswl - what causes what sounds like a cat fight when tuning away from Fc?  (Read 12685 times)
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w4bfs
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« on: July 28, 2016, 08:22:49 AM »

I still enjoy broadcast band short wave listening and have certainly noticed the rapid declines in number of stations.  Most of the low power day stations that I hear have a lot of distortion in the detected audio as you tune away from their carrier frequency.  It sounds like a nasty cat fight and seems to extend about 10kHz away in both directions.

Is this overmodulated PWM ?
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Beefus

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« Reply #1 on: July 28, 2016, 08:50:37 AM »

If you have an SDR received take a look at the bandwidth of their signal. Many station's now broadcast an additional digital content called IBOC, supposedly giving them an "HD" signal.  This extra digital content destroys the two adjacent channels, making DXing almost impossible. You will definitely see the wide bandwidth on a panadapter. Lere in the NYC metro area WOR (710) is the biggest offender. See the story below.

Yes, I miss the days of listening to CKLW, WOWO, KSL and WBT, all of which have either altered their coverage or are now covered by low power stations.
I've still got all my QSL's from the 60's thru the 80's!

http://www.radioworld.com/article/wor-goes-39hd39/16384
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« Reply #2 on: July 28, 2016, 10:43:54 AM »


I have yet to see, hear, find, or know of anyone who has a receiver that decodes IBOC!

WHO is using IBOC receivers??

Where are they being sold?

WHY is any station USING this crap??

What am I missing...Huh?? Huh
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« Reply #3 on: July 28, 2016, 12:24:55 PM »

My HD radio is playing as I type. Great audio quality. Been around for years.

http://hdradio.com/what-is-hd-radio
http://amfone.net/Amforum/index.php?topic=12092.0
http://hdradio.com/blog/thoughts-radios-digital-future
http://www.radioworld.com/article/hd-radio-is-it-worth-the-effort/23658

HD Radios on Amazon
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« Reply #4 on: July 28, 2016, 12:29:44 PM »



sure, you went and bought one, I suppose... but as I said, I have never seen or heard one, never seen one advertised. Don't even know if new cars have that capability in the radios?? Nobody has ever said a word to me about having one... heard a lot about Satellite Radio.  Happen to have one in my car (came with it)

                      _-_-
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« Reply #5 on: July 28, 2016, 03:51:28 PM »

We've had several HD radio threads over the years on the forum. Back 8 to 10 years years ago there was a number of home receivers, portables, AM/FM tuners, and clock radios that came with HD. Over the years, one by one they seem to disappear from the home market and only HD receivers for cars were in abundance. It seemed like a lot of the HD home receiver market was replaced with internet radio receivers. The nice thing about HD radio, especially on FM,  is that you can receive the HD sub channels if a station is equipped to broadcast them  plus the fidelity is considerably better then your typical FM stereo broadcast. So a typical HD FM station can have multiple formats that you can choose to listen to. And HD radio listening is free.

Now I see there are more of them either on the market or coming to the market soon.
I bought a Sony XDR-S3HD radio years ago because it was reported here that the FM HD sound was fantastic and the AM side had great selectivity and was quite sensitive in picking up distant AM stations. I have it here in the office.



For the man cave 4-channel setup, I got myself a Sangean HDT-1X AM/FM HD tuner. With the outside 6 element FM antenna, this thing can pick up stations for hundreds of miles on a good propagation day. Even with the AM antenna loop in the man cave, picking up Canadian AM stations is not a problem.



In August, Sangean is introducing the new HDT-20 AM/FM HD tuner:



They also have the HDR-16 and HDR-18 receivers.
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« Reply #6 on: July 28, 2016, 04:07:38 PM »

I still enjoy broadcast band short wave listening and have certainly noticed the rapid declines in number of stations.  Most of the low power day stations that I hear have a lot of distortion in the detected audio as you tune away from their carrier frequency.  It sounds like a nasty cat fight and seems to extend about 10kHz away in both directions.

Is this overmodulated PWM ?

Most likely you are hearing the digital artifacts of the DRM transmission system if listening to BC SW and here is a summary

http://www.radio-electronics.com/info/broadcast/drm/drm-digital-radio-mondiale.php

Any digital transmission system creates noise in the sidebands, as does IBOC in the MW BC band and which is often called, "In Band Buzzsaw."

Quite frankly, I have never heard any IBOC signal sound any better than a Motorola C-QUAM system.

The only saving grace to an IBOC (HD) receiver is it can decode Motorola C-QUAM.  Wink

Phil - AC0OB

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« Reply #7 on: July 28, 2016, 04:14:01 PM »

Yeah Beefus, the SWL bands seem to be in a serious state of decline and the audio of some stations sounds horrendous.

For AM BCB and FM BCB digital reception I use the Sony XDR S3HD just like Pete. It is completely immune to my late-night transmissions on 160 - 6 meters so it eventually ended up as our bedside radio and I have to say the AM fidelity of the IBOC digital content is quite nice. The FM BCB side of the IBOC equation seems much more practical as they can squeeze in 2 additional full-fidelity CD quality audio content streams for each station. So, just like you see with digital TV, you will get a WTIC -CH1 and WTIC CH2 that have different audio content. The first screenshot below shows the full +25 kHz bandwidth of WTIC-1080 AM running the IBOC protocol. Note that WTIC completely squashes WBAL-1090 in Baltimore in the Hartford market. The second screenshot shows the double-wide full 400 kHz bandwidth of WTIC -96.5 FM.

Rob W1AEX


* wtic am iboc.jpg (89.65 KB, 1219x571 - viewed 317 times.)

* wtic fm iboc.jpg (87.25 KB, 1216x568 - viewed 305 times.)
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« Reply #8 on: July 28, 2016, 08:36:43 PM »

The local oldies station used that IBOC digital stuff. I had to realign the passband of my Stromberg Carlson high fidelity AM tuner. Later they stopped using it because of complaints from other people using hi-fi equipment and I put the tuner back to normal bandwidth. The funny thing is that I had to worm it out of them that they were doing it and what the unmolested analog passband was. The whole AM BC thing is a shame because on weekends, when you have time to listen to sweet nice music, almost all the stations have gone to full time annoyance-blabbering of cajoling, bleating, and fearmongering ads for investment seminars, precious metals, quack cures, and other garbage and scams. Sad they have to do that to stay on the air. and no I am not interested in paying for 'services' nor having to click on some internet thing every time it times out.
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« Reply #9 on: July 29, 2016, 07:50:01 AM »

I have seen digital side band plus analog signals from US BCB transmissions but not from foreign SW signals. Not saying it doesn't exist just I haven't seen one yet. I have seen all digital SW signals but they are declining. It is amazing to tune across a very weak digital SW signal and hear a full quiet transmission. If the signal fades it just clicks out than clicks on as conditions improve. The threshold is quite low.

Mike
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« Reply #10 on: July 29, 2016, 07:53:06 AM »

Great minds think alike! I've wondered the same thing since day 1


I have yet to see, hear, find, or know of anyone who has a receiver that decodes IBOC!

WHO is using IBOC receivers??

Where are they being sold?

WHY is any station USING this crap??

What am I missing...Huh?? Huh
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« Reply #11 on: July 29, 2016, 10:25:13 AM »

And they dropped the AM passband down to MUD.

We have an NPR station here, WAMC that broadcasts the same feed, mostly local programming, on both AM and FM. The AM sounds like you took a blanket and dropped it over your speakers... FULL MUD.

In order to make that 6kHz passband sound right, it seems they'd need some "emphasis" going up from 3-6kHz.
If they are doing that, it don't work. Sad

This holds true for all the AM stations, they all sound like MUD. MUD MUDMUD.

Even on the same "radios" I used back in the day, it sounds like ca-ca today. Especially music.

And then they write about how AM is "struggling" in Radio World? No kidding.
Do on AM what AM DOES BEST, that's the ticket.
Trying to make AM broadcast into FM or "digital" is NEVER EVER going to work.

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« Reply #12 on: July 29, 2016, 02:00:51 PM »

Optimod FM feeding both transmitters,  bear?

I noticed my FM presets sound....   Meh when received on am.


--Shane
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« Reply #13 on: July 30, 2016, 12:01:32 AM »

Many AM broadcast stations have discontinued HD.  Remember, for broadcast radio, AM and FM, HD means "hybrid digital", not high definition.  The typical data compression used for the audio on FM is roughly equivalent to a 48 kHz internet stream.  For AM, its typically 32 kHz.  For both AM and FM, it's a far cry from "better than CD".  In fact it is markedly "lower fi" than CD.  The frequency response is there out to beyond 15 kHz for HD, but the coding/decoding artifacts are audibly maddening to many listeners.

The AM HD sidebands are using the channel from about 5 or 6 to 15 or so kHz away from the carrier.  The FM HD sidebands are spread out to roughly 150 kHz away from the center frequency.

Newer AM receivers have to chop off all audio response above 5 or 6 kHz so the "buzz" or "hash" from the digital sidebands does not make it through the rest of the audio system.  Also, because of the incredible rise of the noise floor over the past several decades, most receiver manufacturers have used IF filters with a bandwidth of less than 6 kHz (+/- 3 kHz) from frequency center.  However, the HD radios, WHEN RECEIVING HD, have filters about 30 kHz wide, to allow the HD sidebands through to the HD decoder.  Those are switched out, or the IF is additionally filtered when in analog AM mode.

I don't know if we will ever be able to enjoy AM radio broadcast reception like we used to 3 or more decades ago.  A number of AM stations have begun firing up (when they can find a frequency) low power FM translators to simulcast their AM programming.  Those translators are granted with the proviso that the FM coverage can not exceed the 2 mv/m AM signal contour. That results in a number of teeny tiny FM signals good for about 5 or 6 miles.

We do live in interesting times.  The only thing we know for certain is that things will always be changing.

What I would like to see happen is for a receiver manufacturer to build a simple consumer SDR for AM and FM broadcast, both for the car and for the home.  Synchronous detection could be used for AM, and modern SDR techniques could be used for FM as well.  I have heard unsubstantiated rumors that some of the manufacturers have given that some thought.  But another problem for them is due to so much listening being done online, wi-fi, streaming, etc., that "radio" is quickly perceived as being obsolete.  Much of that kind of thinking is due to miserable programming, but that is for a different discussion.

73 and happy listening
Ted  W8IXY
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« Reply #14 on: July 30, 2016, 05:30:32 PM »

Quote
The typical spectrum occupancy used in the IBOC system is about 3 times that of the bandwith of a normal AM signal (approx. 10 KHz). Additional digital information is broadcast together with the analog signal as shown in the diagram below.
If there is another station broadcasting quite close to it, the digital information will interfere with the first and second adjacent channel signal. If two stations 10 or 20 kHz apart both use IBOC, they will both have digital signals in the same spectrum. Nighttime use of the AM band will be seriously compromised.


http://www.e-lessons.org/drmlectures/section1/section1d.html


Had we in AM BC been allowed to use the same 30kHz bandwidth, we could have had the full audio spectrum of 15 kHz transmitted in analog Stereo (as in enhanced AMAX), which would have competed with FM. (20% of the bandwidth of mono FM).

With today's technology, it would be a simple matter to transmit full fidelity AM audio.

But the FM money, the buy-out  of the FCC by major interests and the FCC's indecision, and the reluctance of receiver makers to develop wide-band receivers (again due to the FCC's indecision to converge on an early AM-Stereo standard), AM, in some markets, have had to go to sports/talk formats.

BTW, the expanded AM band was supposed to have given preference to local and regional stations intending to use AM stereo exclusively.

We have a number of mom and pop rural AM stations from 250 Watts to 1 kW that have fantastic audio, so AM need not to be boring or have "muddy" audio.  Wink

Phil - AC0OB

If you don't like the programming on AM you do have a choice of changing channels or hitting the "Band" button on your radio. Grin



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« Reply #15 on: July 30, 2016, 06:57:30 PM »

In 2010, the US-mandated digital radio system, IBOC (for "in band on channel") was among Cnet's “The Decade’s 30 Biggest Tech Flops.”

It was not only doomed from the start, it was such a serious blunder that it may well lead to the death of thousands of radio stations and the permanent stunting of the industry itself.

But there is nothing wrong with the concept of digital radio.

Using modern firmware-upgradeable codecs, orthogonal FDM transmission, and a network of community transmitters in a dedicated digital band, great things could have been done:

1. In every community, all signals would have been full-quieting with no noise or multipath distortion. There would have been no more disparity in signal or noise levels between 50-kW powerhouses and 250-Watt locals or 10-Watt student stations — all would have had perfect, full-quieting signals within the community’s coverage area.

2. There would have been no more need for any licensees to sign off or go to absurdly low power at night as obtains presently among AM stations. And former AM stations would no longer suffer from crippling skywave interference at night.

3. Depending on how much spectrum was allocated and the ratio of talk to music programming (with their different bit rates), at least four to eight times as many stations could have been allocated to each community as now exist, leaving open the possibility of free and independent public access and non-profit “free radio” style programming, greatly expanding listening choices (and points of view in news programming) for everyone.

4. As stations migrated to the new band, even more channels would become open on the existing AM and FM bands, making them more listenable and viable again and allowing even more space for non-profits and those who want to broadcast for the love of it -- instead of just for monetary gain.

Digital community-transmitter-based radio in a dedicated digital band thus could have been a tremendous success and a revolutionary improvement.

But we didn’t get real digital radio.

Instead we got IBOC (In-Band On-Channel, now deceptively labeled “HD Radio”), a technical turkey which delivers almost none of the benefits above and increases interference to boot.

Why did this happen?

Because the money-men didn’t want the benefits of item (1) above. They already owned the 50-kW powerhouses. They didn’t want the 10-Watt student station to suddenly have an equal signal to theirs. They didn’t want the mono AM daytimer to suddenly have 20-kHz digital stereo with no audible noise and be on 24 hours a day as in item (2).

And the money-men didn’t want dozens of new independent channels to be available to listeners as in item (3) above.

So they chose IBOC, where the digital signal piggybacks on top of the existing analogue signal, right on the same frequency. IBOC gives distinctly inferior results. IBOC causes significant interference. IBOC on AM is unlistenable to anyone with an ear for good fidelity and very nearly useless.

But IBOC gave the money-men the one thing they wanted most of all: It preserves the inferiority of the smaller broadcasters. In fact, amid a sea of IBOC hash from the big boys, it accentuates their inferiority.

The end result of this shortsightedness will be bankruptcy for many stations, fewer and poorer choices for the listeners as conglomerates gobble up the remains, and a huge migration away from AM and FM broadcasts and to audio delivery via satellite and the Internet.
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« Reply #16 on: July 30, 2016, 07:49:35 PM »

If the AM broadcast band when away tomorrow, I wouldn't care. It has absolutely no program material that I have an interest in. Talk radio garbage is boring. If the 50KW AM stations want to broadcast 20 Kc or more bandwidth, it's no loss. The only time I've flipped the AM radio on in the car was to get a highway report on either the upper or lower end of the band. With the FM HD stations, the quality is great and the program material is varied so I have many entertainment choices.
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« Reply #17 on: July 30, 2016, 10:24:56 PM »

IBOC  fiasco or not.

I pay 50 bucks a month for unlimited internet on my phone.

I employ an adblocker.   I hear very little in the way of commercials,  and I can listen to the stations anywhere in the world.

The only time.ive used the tuner in the truck lately was to use the FM modulator I bought.......   To listen to my phone.

Radio is dead.   It's got about another 30 years and my generation will be dying off.   My kids don't have,  haven't asked for,  and could care less about my home stereo.   Except that it has a 3.5 mm plug snaking out the front.

For their phones.

--Shane
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« Reply #18 on: July 31, 2016, 12:56:24 AM »

Shane, no clue what WAMC does as far as source distribution out to their transmitters...

...you get unlimited data?? what plan - want!!

As far as radio, yes, internet killed the radio.

The "phone" is now king.
The big problem is how to make $$ IF you are on the programming side.
That's the gorilla in the room.

No doubt the big boys never want competition.
They killed independent uplinked programming in the earlier days of C band satellite TV.
In fact they killed satellite TV in general.
This DISH TV and the like is mostly worthless programming.
So is the carp sent out on the TW cable. Less than 10 stations I would want to watch.
No time for movies... So what the heck is one 200-1,000 "channels"??

The last thing they want is creative independent programming.
They seem to have found a way to put a lid on internet "radio" stations too.
Sure you can buy a box that alleges to get "internet radio stations", but it all sounds like
a bunch of homogenized middle-of-the-road and predictable stuff...

Whatever...

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« Reply #19 on: July 31, 2016, 01:11:47 PM »

I found pretty much the same thing,  bear.   If you want any real 'content'  (we called it programming or,  God forbid,  "a show"),  the podcast is where it's at now.

IHeart radio is the biggest app I use.   It's not  ousted against my data,  either.  I've tried Pandora (good)  and a few others.   But I miss the RADIO PERSONALITIES.....   And those ARE going away.   Which makes IHeart app OK,  since it let's me listen to what I want. 

T
Problem with podcast is:  Finding something you actually wanna listen to in the first place.

As to the  phone plan.   Believe it or not,  MetroPCS.   40 bucks a month gives me 6 gig at 4G speed,  then I'm at 3G for the rest of the month.   For 60, it truly is unlimited 4G, Ive cranked up 55 gigs in one month,  streaming a Netflix movie every night and audio during the day,  in addition to email,  etc.   I use the phone to tether as well.   And,  here's the kicker.   If you are on the 50 a month plan,  and see you are going to go over and it's 15 days into the month,  call them.   For 5 bucks,  you upgrade to unlimited.

They ride on T Mobiles network where t-mobile is built out.   Otherwise,  it's on Verizon.

Even their 40 a month plan,  after I believe 2 gigs,  just slows down.   There is NO data cap.   And every line you bring on,  drops the  price 5 bucks. 

Best deal I've found if they are in your area.   Top it off with a completely waterproof phone for 40 bucks,  runs android,  and you can throw it in a pool or the river (I do for the  kids to find),  I don't think I can find better.

Didn't mean to shill for metro.....
  But they have really gotten their act together in last couple years.   Back to our regularly scheduled tech talks.


--Shane
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« Reply #20 on: August 03, 2016, 05:43:03 AM »

subject near and dear to my heart. It is all about the money. Over the air radio broadcast is free to listen to. Anything else that requires a monthly payment to listen is out of the question here. I WILL NOT PAY TO LISTEN TO MUSIC DELIVERED BY A CELLULAR INFRASTRUCTURE OR SATELLITE. I could go on and on about how radio has shot itself in the foot. The FCC is trying to figure out how to improve AM radio.(1) Eliminate HD radio (2) Stop trying to rewrite the laws of physics when it comes to nighttime skip propagation. (3) the technology is here to demodulate an AM signal far more effectively than a diode detector.(4) Drop NRSC requirements for most stations during daylight hours. In most cases chopping the high end @ 10Khz does not cause a potential adjacent channel interference problem as it does at night.This will allow for full high fidelity band width.(5) If so called HD am is to continue ,restrict it's use to daytime hours only as it was in the beginning. Re-read the comments from Kevin WB4AIO ,and Ted W8IXY THEY make perfect sense.The low bit rate especially for the AM IBOC system does not make any sense to continue it's operation. In my way of thinking the low band TV VHF channels, mostly unused now,  CH 5,and 6  should be added on to the bottom of the FM BCB. This should be for full digital transmissions only. A single digital carrier occupying a 100 Khz bandwidth could carry a number of full bandwidth stereo as well as medium Figh mono streams for talk radio type formats. A typical higher end AM/ FM radio would continuously cover from 76-108 Mhz. The radio would recognize the digital or analogue FM signals seamlessly . The AM end of it would incorporate low distortion sync detection and noise reduction circuitry, plus the ability to open up to a full 30Khz bandwidth. I doubt there would be any interest for the industry to get it's head out of it's @&% and go this route. many of us are too used to being hooked up to the interveinous feed from some pay by the month service. Pay for it or we will cut you off ,,,and you might as well be living in the stone age.
Tim WA1HnyLR
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« Reply #21 on: August 05, 2016, 09:26:14 AM »

We've had several HD radio threads over the years on the forum. Back 8 to 10 years years ago there was a number of home receivers, portables, AM/FM tuners, and clock radios that came with HD. Over the years, one by one they seem to disappear from the home market and only HD receivers for cars were in abundance. It seemed like a lot of the HD home receiver market was replaced with internet radio receivers. The nice thing about HD radio, especially on FM,  is that you can receive the HD sub channels if a station is equipped to broadcast them  plus the fidelity is considerably better then your typical FM stereo broadcast. So a typical HD FM station can have multiple formats that you can choose to listen to. And HD radio listening is free.

Now I see there are more of them either on the market or coming to the market soon.
I bought a Sony XDR-S3HD radio years ago because it was reported here that the FM HD sound was fantastic and the AM side had great selectivity and was quite sensitive in picking up distant AM stations. I have it here in the office.



For the man cave 4-channel setup, I got myself a Sangean HDT-1X AM/FM HD tuner. With the outside 6 element FM antenna, this thing can pick up stations for hundreds of miles on a good propagation day. Even with the AM antenna loop in the man cave, picking up Canadian AM stations is not a problem.



In August, Sangean is introducing the new HDT-20 AM/FM HD tuner:



They also have the HDR-16 and HDR-18 receivers.

You're right on Pete. The FM HD signal IS CD Quality audio, whereas Sirius-XM radio are really miserable MP3's at best. I do not know the bit rate for Sat radio on its music channels. I read it varies, depending on the genre. The news-talk is worse.
At least with FM Iboc, the stations do not interfere with each other, unless they're too closely spaced on the adjacents. Once again, the full legal bandwidth of the FM station is utilized, where with the main and stereo sub carrier and maybe an SCA or RDS; the full bandwidth is never used.
AM HD radio is amazing but the crude idea of increasing bandwidth to make it "compatible' with analog AM was its failure. The FCC is hearing the cries of the folks who enjoyed the out of town stations and DXing, believe me!!

Fred
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« Reply #22 on: August 05, 2016, 06:55:14 PM »

I still enjoy broadcast band short wave listening and have certainly noticed the rapid declines in number of stations.  Most of the low power day stations that I hear have a lot of distortion in the detected audio as you tune away from their carrier frequency.  It sounds like a nasty cat fight and seems to extend about 10kHz away in both directions.

Is this overmodulated PWM ?

Most likely you are hearing the digital artifacts of the DRM transmission system if listening to BC SW and here is a summary

http://www.radio-electronics.com/info/broadcast/drm/drm-digital-radio-mondiale.php

Any digital transmission system creates noise in the sidebands, as does IBOC in the MW BC band and which is often called, "In Band Buzzsaw."

Quite frankly, I have never heard any IBOC signal sound any better than a Motorola C-QUAM system.

The only saving grace to an IBOC (HD) receiver is it can decode Motorola C-QUAM.  Wink

Phil - AC0OB



that was an awesome system. It didn't interfere with other stations. And sounded great. Super!!! I think it was only available in GM vehicles during the 80's

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« Reply #23 on: August 07, 2016, 08:41:49 PM »

Shane, no clue what WAMC does as far as source distribution out to their transmitters...

...you get unlimited data?? what plan - want!!

As far as radio, yes, internet killed the radio.

The "phone" is now king.
The big problem is how to make $$ IF you are on the programming side.
That's the gorilla in the room.

No doubt the big boys never want competition.
They killed independent uplinked programming in the earlier days of C band satellite TV.
In fact they killed satellite TV in general.
This DISH TV and the like is mostly worthless programming.
So is the carp sent out on the TW cable. Less than 10 stations I would want to watch.
No time for movies... So what the heck is one 200-1,000 "channels"??

The last thing they want is creative independent programming.
They seem to have found a way to put a lid on internet "radio" stations too.
Sure you can buy a box that alleges to get "internet radio stations", but it all sounds like
a bunch of homogenized middle-of-the-road and predictable stuff...

Whatever...

                           _-_-bear

AT&T cellular with a DirecTV account is unlimited data  on all three of our cell phones. After 22Gb of data, AT&T may choke off your speed toward the end of the month.;

Fred
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Fred KC4MOP
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« Reply #24 on: August 09, 2016, 07:24:58 PM »




that was an awesome system. It didn't interfere with other stations. And sounded great. Super!!! I think it was only available in GM vehicles during the 80's



It was Chrysler vehicles that had C-QUAM radios.  My '89 Dakota and the '91 LeBaron both had C-QUAM receivers that sounded quite decent.  GM radios of the era, AFAIK, did not, and had pretty narrow selectivity so they didn't sound nearly as great.
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FCC:  "The record is devoid of a demonstrated nexus between Morse code proficiency and on-the-air conduct."
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