Gee, I feel like I'm dumber than a box of hair, since I have no idea of what you are trying to say above. In fact, I really don't see how anything above can "save" amplitude-modulated radio broadcasts that rely on propagating signals into "the air".
Am I alone on this?
Why not expand FM dial down to 76 MHz?
But most Central and South American and Caribbean stations use slogans as their main IDs: Radio Musical, Radio Tropical, Radio Reloj, Radio Rebelde, etc. Australian stations use odd number-letter combinations like 2FJ and 8JX; I wouldn't call them callsigns, I'm really not sure what they are. Maybe the prefix (VK? VL?) that would turn them into legitimate calls is omitted?
People don't listen to call signs. They listen to programming. If you change the call sign and don't touch the programming, you will not lose a single listener.
An FM band expansion would take years to complete. It would require relocation of or sharing the spectrum with the remaining TV signals. It might also require co-ordination with Canada and Mexico. It would require large financial investments on the part of AM radio operators to switch bands (into what is currently an RF wilderness) and promote the change to the listeners they have remaining.9 kHz? Would be ok on analog radios but not digitally tuned ones. New radios needed, old ones obsolete. Why not expand FM dial down to 76 MHz? Sure new radios could pick up the new stations but not old ones. All kinds of freq switched on AM to squeeze more stations in.
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An FM band expansion would take years to complete. It would require relocation of or sharing the spectrum with the remaining TV signals. It might also require co-ordination with Canada and Mexico. It would require large financial investments on the part of AM radio operators to switch bands (into what is currently an RF wilderness) and promote the change to the listeners they have remaining.
In that time, who knows whether portable internet technology will make all this a moot point or whether there will be any AM radio stations worth saving.
I think we should focus on ideas that REPAIR the current state of the AM band, instead of looking towards the Internet. For starters, rescind HD operation on the AM band; too much splatter into adjacent channels, not to mention background hiss on the main analog channel. Next, rescind permission for all those daytimers who operate at night with super powers of 5000 milliwatts or so. And, since Canada turned off a good many of its AM stations (yes, they migrated to FM), allow those stateside operators who were protecting Canadian AMs to alter their directional patterns. Granted, this cannot happen overnight, but should be among those ideas considered by anyone serious about saving AM.
If, OTOH, you want a quick solution, or want to throw in the towel re noise/interference from computers et al, just tell the public that all AM transmitters will be turned off on some future date, and everything formerly on-the-air will be moving to the Internet. Let me know how well that works out.
I have read that someone has devised a way to eliminate skywave with filters installed at the transmitter. If so that could be the solution.
Look skywave reception no longer has a valid reason to exist ( and skywave listeners have not contributed to a stations bottom line in decades ) - If it could be done stations would no longer need massive transmitter sites for directional signals, and could deliver a signal to all parts of the local area.
Nice idea, but filtering at the transmitter won't eliminate it. Radio waves (both groundwave and skywave) are radiated from the antenna, and whether or not skywave is radiated is wholly dependent on the antenna's design. Specific antenna designs can minimize it, but as of yet no one has figured out a way to eliminate it.
A point some of us have been trying to make through all eight pages (so far) of this thread. DX'ing is irrelevant to the business of radio. Some get it, some don't.
However: Skywave reception (and the interference it causes at distances of hundreds or thousands of miles) is going to occur whether we like it or not. We can't just wish it away. It is caused by the laws of nature and physics, and as some people have yet to learn (i.e., Congress), you can't legislate it away either.
And, since Canada turned off a good many of its AM stations (yes, they migrated to FM), allow those stateside operators who were protecting Canadian AMs to alter their directional patterns. Granted, this cannot happen overnight, but should be among those ideas considered by anyone serious about saving AM.