AM in the "FM" Band

[kfbkfb]

Why not place (AMAX) compliant AM signals in the unusable (for FM, maybe be usable for all digital HD Radio) RF segments in the current FM band?

My (since partially discredited) sketch of part of the FM band in KC indicated that 94.3 and 94.7 were empty, multiple (new) AM signals could be placed there, perhaps bandlimited to ~5kHz to keep them in a 10kHz frequency slot.

The noise disrupting AM in its current band isn't in the FM band and also the AM signals would be limited to "line-of-sight", so AM in the FM band frequencies could be reused more easily.

Would just need to develop AM radios that tuned in the FM band too, no new transmitting or receiving tech would be needed.


Kirk Bayne

 

[Miss Tuned]

These ideas are getting more and more outlandish. Why not place Star Trek subspace emissions in the short wave band?

 

[KeithE4]

A similar system called Apex was tried in the 40-45 MHz region in the late 1930s. It went nowhere. It was quickly replaced by the original 42-50 MHz FM band by the time World War II started.

Again, this is an idea that doesn't need to exist.

 

[semoochie]

Are you talking about amplitude modulating stations between 88 and 108MHz?

 

[Mediafrog+]

It was quickly replaced by the original 42-50 MHz FM band by the time World War II started.

Occasionally you see idle chatter about reviving that band for AM migration. Of course you would have the same problem as with expanding the current FM band down to 76 MHz.

If that was to happen, it would be amusing to see the reaction from those who still have one of the original cordless landline phones from the late 70's/early 80's wondering why they hear sportstalk or Spanish language religion while trying to make a call...

 

[kfbkfb]

Yes, AM signals in the "FM" band of ~88MHz to ~108MHz - in the frequency slots that can't be used for FM or FM + HD Radio (but maybe HD Radio only).

Since it would be a new, closed system (using AM in the FM band), perhaps a high NR system such as dBx could be made part of the standard, potentially reducing noise that might be added to the AM signals (from FM/FM + HD in that frequency slot in a nearby radio market [per FCC allocation rules]).


Kirk Bayne

 

[Kelly A]

Why not place (AMAX) compliant AM signals in the unusable (for FM, maybe be usable for all digital HD Radio) RF segments in the current FM band?

Among many reasons; because AMAX sounds like crap? Decades ago I attended an NAB where AMAX was being demonstrated. You could put some headphones on and hear the wonders of stupid AMAX. What I noted was a high pitched whistle, even in the display conditions. Took the headphones off, and the guy running the booth said: Waddya think?? I answered; 'What's with that awful whistle??' The smiles from folks in the booth suddenly went sour. 'Well, most people can't hear the whistle anyway'. My response was: 'Are you insane??' Why on God's green earth would you promote an inferior product that whistles??
And the same could be said for your suggestion.

Would just need to develop AM radios that tuned in the FM band too, no new transmitting or receiving tech would be needed.

No offense; but this is the dumbest idea you've had to date.

 

[KeithE4]

Occasionally you see idle chatter about reviving that band for AM migration. Of course you would have the same problem as with expanding the current FM band down to 76 MHz.

I don't think that band has ever had anything but narrowband FM on it, at least not in non-governmental services.

If that was to happen, it would be amusing to see the reaction from those who still have one of the original cordless landline phones from the late 70's/early 80's wondering why they hear sportstalk or Spanish language religion while trying to make a call...

The Part 15 rules for those ancient cordless phones are still on the books, but I'd be shocked if there are any still in service.

 

[kfbkfb]

The unused "FM" band spectrum is just sitting there, IMHO, some of it could be used for AM signals.

My AMAX comment was mainly about the 75 microsecond EQ and low distortion associated signal processing rather than extended frequency response.


Kirk Bayne

 

[Kelly A]

The unused "FM" band spectrum is just sitting there, IMHO, some of it could be used for AM signals.

No, it can't. There's this little thing that requires geographical separation. And again; who's buying new radios? Answer: Nobody. What's the growth look like for existing AM stations? Answer: Zero.

My AMAX comment was mainly about the 75 microsecond EQ and low distortion associated signal processing rather than extended frequency response.

AM has been running preemphasis for years. Hasn't helped the issues with distortion, noise, and even AMAX, (beyond the whistle) can't match FM for frequency response or stereo separation.

 

[secondchoice]

I have always wonder why the old VHF low band 54-88 MHZ with really does not work that well for DTV wasn't devoted to a AM and FM stations kind of a "community" digital deal. A digital radio receiver should easily tell the difference between TV and radio signals. You can pack a lot of digital signals in 4 MHz channel so most of the market could be "digital". It could work where a station's RDS "tells" where the digital signal is and the receiver switches to it automatically. Or the receiver "finds" the available digital signals and matches it to the frequency. When you tune a station's analog frequency it will switch to the digital on if present.

 

[Kelly A]

I have always wonder why the old VHF low band 54-88 MHZ with really does not work that well for DTV wasn't devoted to a AM and FM stations kind of a "community" digital deal. A digital radio receiver should easily tell the difference between TV and radio signals. You can pack a lot of digital signals in 4 MHz channel so most of the market could be "digital". It could work where a station's RDS "tells" where the digital signal is and the receiver switches to it automatically. Or the receiver "finds" the available digital signals and matches it to the frequency. When you tune a station's analog frequency it will switch to the digital on if present.

But again: WHO'S BUYING RADIOS THAT WOULD TUNE AN EXPANDED BAND?

 

[Miss Tuned]

Rolling out DAB would be a better, more workable solution than any of the madcap proposals from Kirk. The system is proven in multiple countries, the receivers are available and very cheaply mass-produced, and the standard is open. It'll still never happen in the U.S., which tells you all you need to know about the crazy schemes that get posted here ad infinitum that would require new types of receivers and transmitters to be invented.

 

[Kelly A]

Rolling out DAB would be a better, more workable solution than any of the madcap proposals from Kirk.

Beyond Kirk's wacky suggestions; when rolled out in: Australia, Czech Republic, Denmark, Germany, Hong Kong (now terminated), Italy, Malta, Norway, Poland, Switzerland, Belgium, the United Kingdom and the Netherlands, DAB has had mixed success, mostly negative.
DAB migration in the U.S. would be the death of radio as we know it. Why? For exactly the same reason as David and I have been harping on: Consumer's will not go out and buy new radios. Period. When stations were force-migrated to DAB, almost immediately lost over 50% of their audiences.

 

[davideduardo]

The unused "FM" band spectrum is just sitting there, IMHO, some of it could be used for AM signals.

Read this slowly: any change is bands or transmission systems that require buying a new stand-alone device will fail. Period.

 

[TheBigA]

Would just need to develop AM radios that tuned in the FM band

As I in the previous thread, the Consumer Electronics Association has given up on radio.

The electronics industry isn't developing new radios. That ended a long time ago.

 

[davideduardo]

Beyond Kirk's wacky suggestions; when rolled out in: Australia, Czech Republic, Denmark, Germany, Hong Kong (now terminated), Italy, Malta, Norway, Poland, Switzerland, Belgium, the United Kingdom and the Netherlands, DAB has had mixed success, mostly negative.
DAB migration in the U.S. would be the death of radio as we know it. Why? For exactly the same reason as David and I have been harping on: Consumer's will not go out and buy new radios. Period. When stations were force-migrated to DAB, almost immediately lost over 50% of their audiences.

Canada, which of all the nations you named, has about the highest percentage of listening to commercial stations tried DAB and abandoned it when they saw that consumers saw no advantage and did not buy the equipment.

Even in the UK, many listeners who are in rural areas or small towns or where there is rugged terrain have found that DAB is not effective. The policy makers in London hear it just fine, and never think that it is really not so good.

 

[Mediafrog+]

Canada, which of all the nations you named, has about the highest percentage of listening to commercial stations tried DAB and abandoned it when they saw that consumers saw no advantage and did not buy the equipment.

Apparently DAB in Canada simply duplicated existing AM and FM stations. There was no new or unique content, so no incentive to buy the receivers.

Canada's DAB system also used L-Band frequencies between 1452 and 1492 MHz, greatly different from the European DAB stations in the 220 MHz range.

 

[davideduardo]

Apparently DAB in Canada simply duplicated existing AM and FM stations. There was no new or unique content, so no incentive to buy the receivers.

Canada's DAB system also used L-Band frequencies between 1452 and 1492 MHz, greatly different from the European DAB stations in the 220 MHz range.

But, basically, DAB failed because there was no huge governmental obligatory push for implementation. When left to the open or "free" market, there were no incentives for the existing radio services to be phased out.

And in Europe, the added content in some... but not all nations... has turned out to be very fringe in appeal and not the reason for consumers to move to DAB. The main reason is the phasing out of the whole AM band and supposed "digital quality", all pushed by the government.

 

[Kelly A]

But, basically, DAB failed because there was no huge governmental obligatory push for implementation. When left to the open or "free" market, there were no incentives for the existing radio services to be phased out.

And even if the government force-moved existing stations to DAB, consumers would just not bother making the move. That would be the end of radio.