Something that actually WORKS on AM

[Kelly A]

Back when the whole HD/IBOC rollout began in the early 2000's, I sent recommendations to both the NAB and the FCC, regarding a possible migratory process for taking the AM broadcast band digital. The plan would be to allow exiting AM broadcasters in major markets, to apply-for and construct 1KW ND all-digital modulated simulcast stations in the expanded band 1605-1705kHZ range. Depending on the location and facility, each 1KW digital station would have the approximate coverage of a 5kW analog station because of the native RMS modulation rather than traditional analog AM-peak. After 10 years, the licensee of both stations could decide whether to abandon their analog modulation on their main facility, modulating digital, or re-up for another five years of digital/analog simulcasting. I still believe the idea has a certain amount of merit.

 

[Carmine5]

The second is that converting to digital would free up spectrum. It would not, because as I understand it, the digital only version of the HD broadcast is still designed to fit in the same 100 kHz space of an analog station, which means that unless there's some major change in radio design, the current spacing and separation rules will need to be kept in place.

The truth of the matter is the FCC could have done almost the exact the same spectrum repacking with analog stations as they did with the digital transition, if they wanted. The additional channels gained on the TV side are not real, they're subchannels. So unless your local TV station is going to be willing to lease out an equal amount of bits to a competitor, it's not really adding competition even if digital did add channels. And I should note that, like HD, when you add subchannels, you take away quality from the main channel.

This is not entirely correct. DTV uses less bandwidth and is inherently more resistant to interference than analog. Plus the FCC has strict mask filter requirements for DTV. Because of this, during the DTV transition the FCC was able to eliminate the so-called UHF "taboo" channel spacing requirements and pack more channels (and stations) on the UHF band in a given DMA then was previously possible with analog. It's also why TVWS is possible in the guard bands.

The question is: would this also be the case with the FM band should it go all digital? I believe it would.

 

[Kelly A]

This is not entirely correct. DTV uses less bandwidth and is inherently more resistant to interference than analog. Plus the FCC has strict mask filter requirements for DTV.

Granted to an extent, as many OTA analog TV viewers would be generally more accepting to effects of multipath (ghosts) and impulse noise (sparkles or lines in the video). ATSC-8VSB DTV broadcasting is less resistant to both multipath and impulse noise on the receiver end. Excessive multipath or impulse noise and DTV reception simply goes away (cliff effect), in spite of field strength at the receiver. This confuses OTA viewers, because their "signal" indicators of a DTV receiver isn't actually indicating carrier level, but signal quality.

COFDM DTV is more resilient to multipath and noise, but it wasn't selected for a modulation standard in the U.S.

 

[Casey]

Digital doesn't seem to be the answer to AM's problems. Perhaps it is time to reinvestigate narrow-band FM on the AM band? I know it has been mentioned before on this board.

 

[Kelly A]

Narrow band as in 10khz deviation? Even amateur radio FM deviation is more than that, with less audio quality than AM has now.

 

[pianoplayer88key]

But, if we used FM, even narrowband, on mediumwave, wouldn't it require a wider bandwidth to get the same frequency response?

Question. Of the analog modes, does SSB have the most efficient bandwidth occupied vs audio bandwidth transmitted scheme? Or are there more efficient ones without going into digital encoding?

 

[Kelly A]

But, if we used FM, even narrowband, on mediumwave, wouldn't it require a wider bandwidth to get the same frequency response?

Yes

Question. Of the analog modes, does SSB have the most efficient bandwidth occupied vs audio bandwidth transmitted scheme? Or are there more efficient ones without going into digital encoding?

It has an advantage when it comes to signal propagation, because the modulated/occupied bandwidth is less. Transmitting data requires much more bandwidth because of the amount of data and error correction.

 

[rbrucecarter5]

Back when the whole HD/IBOC rollout began in the early 2000's, I sent recommendations to both the NAB and the FCC, regarding a possible migratory process for taking the AM broadcast band digital. The plan would be to allow exiting AM broadcasters in major markets, to apply-for and construct 1KW ND all-digital modulated simulcast stations in the expanded band 1605-1705kHZ range. Depending on the location and facility, each 1KW digital station would have the approximate coverage of a 5kW analog station because of the native RMS modulation rather than traditional analog AM-peak. After 10 years, the licensee of both stations could decide whether to abandon their analog modulation on their main facility, modulating digital, or re-up for another five years of digital/analog simulcasting. I still believe the idea has a certain amount of merit.

I've often thought a re-allocation of the AM band to create an äll digital "band within a band"- local only, virtually unlimited power would be the best way to have rolled out HD-AM. But we are overlooking an obvious alternative. I am going to get jumped on for even saying this, but it is an option. Longwave appears to have been abandoned even by the aircraft beacons. Shortwave is being abandoned all over the world. Since new radios are needed for HD radio anyway - why not make use of those bands for HD-AM? You could do the job right, allocate enough power to overcome interference sources, channel width enough to make digital actually sound good. Give every existing AM station a digital channel in the opened up bands, provided they vacate their present channel in 20 years, leave just enough on AM that they, too can superpower to overcome interference and run either hybrid or full digital. Do that - and music formats would sound as good on HD AM as HD FM, nobody would care what band stations were on if scan or preset tuning was continuous - a station would be a station. You could have hundreds, if not thousands of frequencies available, immediately, for use by people who can't compete now and people who can't get a license.

 

[KB1OKL]

Back when the whole HD/IBOC rollout began in the early 2000's, I sent recommendations to both the NAB and the FCC, regarding a possible migratory process for taking the AM broadcast band digital. The plan would be to allow exiting AM broadcasters in major markets, to apply-for and construct 1KW ND all-digital modulated simulcast stations in the expanded band 1605-1705kHZ range. Depending on the location and facility, each 1KW digital station would have the approximate coverage of a 5kW analog station because of the native RMS modulation rather than traditional analog AM-peak. After 10 years, the licensee of both stations could decide whether to abandon their analog modulation on their main facility, modulating digital, or re-up for another five years of digital/analog simulcasting. I still believe the idea has a certain amount of merit.

The answer to AM radio is to allow them to broadcast high fidelity like maybe up to 12K and that would interfere with adjacents much less than iBlock and sound better to boot, enforce part 15 rules and to make good receivers that actually have speakers bigger than 2 inches and wide and narrow positions. OK flame away.

 

[davideduardo]

The answer to AM radio is to allow them to broadcast high fidelity like maybe up to 12K and that would interfere with adjacents much less than iBlock and sound better to boot, enforce part 15 rules and to make good receivers that actually have speakers bigger than 2 inches and wide and narrow positions. OK flame away.

Posted in error.l.

 

[davideduardo]

The answer to AM radio is to allow them to broadcast high fidelity like maybe up to 12K and that would interfere with adjacents much less than iBlock and sound better to boot, enforce part 15 rules and to make good receivers that actually have speakers bigger than 2 inches and wide and narrow positions. OK flame away.

Consumers are not buying stand-alone radios of any kind. They want their radio in their smartphone. AM stations would be better served improving the quality of the stream, improving the stopset fillers, adding richer content to the visual sidebars to the stream, etc.

 

[davideduardo]

I've often thought a re-allocation of the AM band to create an äll digital "band within a band"- local only, virtually unlimited power would be the best way to have rolled out HD-AM. But we are overlooking an obvious alternative. I am going to get jumped on for even saying this, but it is an option. Longwave appears to have been abandoned even by the aircraft beacons. Shortwave is being abandoned all over the world. Since new radios are needed for HD radio anyway - why not make use of those bands for HD-AM? You could do the job right, allocate enough power to overcome interference sources, channel width enough to make digital actually sound good. Give every existing AM station a digital channel in the opened up bands, provided they vacate their present channel in 20 years, leave just enough on AM that they, too can superpower to overcome interference and run either hybrid or full digital. Do that - and music formats would sound as good on HD AM as HD FM, nobody would care what band stations were on if scan or preset tuning was continuous - a station would be a station. You could have hundreds, if not thousands of frequencies available, immediately, for use by people who can't compete now and people who can't get a license.

If nobody is buying "radios" today, what makes you think they would buy bizarre multiband AM radios for the niche programming that most AM stations offer today?

Consumers want their "radio" on their smartphone or in their dashboard.

The idea is not practical, as it requires new radios to receive existing content that is no longer mass appeal.

And, except for the longwave idea, you forget that irrespective of modulation method, AM and shortwave frequencies generate skywave. On SW channels, we would only be able to have one station in the whole country, and it would be subject to the use of the frequency internationally where there is still a lot of SW broadcasting.

 

[boombox4]

Consumers are not buying stand-alone radios of any kind. They want their radio in their smartphone. AM stations would be better served improving the quality of the stream, improving the stopset fillers, adding richer content to the visual sidebars to the stream, etc.

Consumers are buying stand alone radios, just not in the numbers they used to. The local Fry's goes through quite a few of them. Shower radios, kitchen radios, workshop radios, etc. All with AM as well as FM.

 

[TheRover]

I have to say, that a couple of the local AM stations in the Dallas area that broadcast in HD, well, their audio quality in HD is just bad. It's tinty, and it is not as good as their non-HD AM feed. I'm talking about major stations like KRLD 1080 AM, and KSCS 96.3 HD-2 (570 KLIF). They must know about the poor audio quality, and just don't care. As for 1080, I don't listen to their programs on a regular basis, just an occasional stop, but I move on. I do listen to KLIF 570 AM frequently, but only occasionally through their KSCS HD-2 channel.

The stations that could really benefit from an HD broadcast due to their musical content, Classical WRR 101.1 and Public Radio KERA 90.1, do *not* broadcast in HD. WRR did at one time, but being a city owned station, who knows what "politics" are behind not now broadcasting in HD.

So, basically, I am not happy with the HD offerings after 9 years. The next car stereo will *not* have to have HD, but instead will have Bluetooth and wi-fi.

 

[rbrucecarter5]

I have to say, that a couple of the local AM stations in the Dallas area that broadcast in HD, well, their audio quality in HD is just bad. It's tinty, and it is not as good as their non-HD AM feed. I'm talking about major stations like KRLD 1080 AM, and KSCS 96.3 HD-2 (570 KLIF). They must know about the poor audio quality, and just don't care. As for 1080, I don't listen to their programs on a regular basis, just an occasional stop, but I move on. I do listen to KLIF 570 AM frequently, but only occasionally through their KSCS HD-2 channel.

The stations that could really benefit from an HD broadcast due to their musical content, Classical WRR 101.1 and Public Radio KERA 90.1, do *not* broadcast in HD. WRR did at one time, but being a city owned station, who knows what "politics" are behind not now broadcasting in HD.

So, basically, I am not happy with the HD offerings after 9 years. The next car stereo will *not* have to have HD, but instead will have Bluetooth and wi-fi.

WRR was probably a coverage issue. While they were doing HD, I had trouble as close in as Jacksboro, which is pretty pathetic. But now that they have dropped it, they dominate the frequency in the northern part of Austin. And make no mistake, that also means they penetrate buildings a lot better, too.

KRLD is another issue - I noticed the decrease in strength. 50 kW used to make it into Houston even with a first adjacent. Now it is a deep fringe, very weak signal. I remember listening to them completely static free at a timeshare on Lake Conroe before HD. I tried them about a year ago - same place, same radio, and was shocked how weak they were.

The only reason I love HD radio is for the HD-2 offerings, formats you don't hear anywhere else. But they will go away if HD ever catches on with consumers. No doubt for rubbish like Kardashian radio, all hip-hop BUTT songs all the time, or other popular drivel. Hopefully satellite and streaming will still be offering more pleasant selections.

 

[K6JHU]

I just got back from Dallas. WRR was ID'ing as WRR, WRR HD1. Didn't have an HD radio in the car so I can't verify.

 

[rbrucecarter5]

It is possible their equipment was down on my last trip to Austin, hence the powerful coverage. No doubt they would be gone if they are now HD - giving Austin oldies listeners a clear shot at KONO. I will try them my next trip to my daughter's apartment in college station - a quick band scan of Dallas frequencies tells me which are currently in HD and which aren't - those not in HD will easily swamp their Houston counterparts. Those in HD will be swamped by Houston, SA, or Austin co channels. Houston stations are also hobbled badly by HD for the most part, but have barely enough strength to put a deep fringe signal into College Station. Unless they have temporarily halted HD, in which case they are strong as locals up there.

 

[Kelly A]

It is possible their equipment was down on my last trip to Austin, hence the powerful coverage. No doubt they would be gone if they are now HD - giving Austin oldies listeners a clear shot at KONO. I will try them my next trip to my daughter's apartment in college station - a quick band scan of Dallas frequencies tells me which are currently in HD and which aren't - those not in HD will easily swamp their Houston counterparts. Those in HD will be swamped by Houston, SA, or Austin co channels. Houston stations are also hobbled badly by HD for the most part, but have barely enough strength to put a deep fringe signal into College Station. Unless they have temporarily halted HD, in which case they are strong as locals up there.

Again Bruce, how does operating HD on FM effect the coverage of the analog portion of the station? Realizing I'm being redundant, mainly because you've avoided answering the same question in many other posts, rather going off on some jag about your listening habits, writing scientific papers, radio brand IF sections, blah.. blah. Please explain how you've arrived at your conclusion?

 

[KB1OKL]

I have to say, that a couple of the local AM stations in the Dallas area that broadcast in HD, well, their audio quality in HD is just bad. It's tinty, and it is not as good as their non-HD AM feed. I'm talking about major stations like KRLD 1080 AM, and KSCS 96.3 HD-2 (570 KLIF). They must know about the poor audio quality, and just don't care. As for 1080, I don't listen to their programs on a regular basis, just an occasional stop, but I move on. I do listen to KLIF 570 AM frequently, but only occasionally through their KSCS HD-2 channel.

The stations that could really benefit from an HD broadcast due to their musical content, Classical WRR 101.1 and Public Radio KERA 90.1, do *not* broadcast in HD. WRR did at one time, but being a city owned station, who knows what "politics" are behind not now broadcasting in HD.

So, basically, I am not happy with the HD offerings after 9 years. The next car stereo will *not* have to have HD, but instead will have Bluetooth and wi-fi.

When I last sampled AM IBOC stations around here of which I could only receive one on my Sony (WBZ 1030 at 40 miles with many drop outs) it sound like it transmitted through a telephone line in analog and sounded excessively sibilant and artificial in IBOC, very tiring on the ears. I think WBZ thinks it's a poster child for IBOC along with WOR NY. Complete waste of time and money.

 

[Wimmmex]

When I last sampled AM IBOC stations around here of which I could only receive one on my Sony (WBZ 1030 at 40 miles with many drop outs) it sound like it transmitted through a telephone line.

I listen to WBZ every day in HD. Sounds great. No dropouts. Announcers sound like they are in the same room...and the commericla s and formatics are in stereo.

AM HD is the best chance for increased fidelity on AM radio right now.