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"Is anyone seriously thinking a lone AM transmitter 2000 miles away is going to help?" It's not for me to explain why in detail here but AM radio communication

"Is anyone seriously thinking a lone AM transmitter 2000 miles away is going to help?" It's not for me to explain why in detail here but AM radio communications is the best value for money of any communications system outside of telegraphy (wired or wireless). It's cheap, simple, easy to construct, and it's scalable to any size (and transmission distance) that's needed. AM radio is one of the greatest inventions of the 20th Century and it's far from outdated. Come the Bomb and or next war and if you have any communications at all then it will almost certainly be AM Radio. AM Radio can be local or long distance and cover the world depending on frequency. Years ago during a sunspot maxima, I watched a friend of mine located in NSW Australia talk to someone in California on 27MHz AM using only three watts of power (from a handheld CB radio) and using only a whip antenna. I defy you or anyone to come up with a simper technology that can do that. If you want to cover say the continental US with radio during, say, a national emergency when nothing else works then it'll be AM radio that comes to the rescue. This simply is why AM radios ought to be made mandatory in every vehicle. This is not even an argument, it's a no-brainer.

deleted 2y ago
[deleted]
ben_w 2y ago
> Years ago during a sunspot maxima, I watched a friend of mine located in NSW Australia talk to someone in California on 27MHz AM using only three watts of power (from a handheld CB radio) and using only a whip antenna. This example makes me think that these wavelengths will be heavily congested in the event of a major global, or even local, disaster.
- squigz 2y ago
  (I know next to nothing about radio) I imagine this would depend on who can transmit "louder"? In the case of a disaster, that would likely be emergency services of some kind
  - ben_w 2y ago
    Yes and no; think of a loud room where everyone is shouting because that's the only way to be heard due to everyone shouting.
redox99 2y ago
AM is awful and outdated. The only benefits it currently has, aren't actually related to the amplitude modulation, but simply a property of the reserved frequency bands it uses.
- hilbert42 2y ago
  "AM is awful and outdated." This, simply, isn't the issue.
jdietrich 2y ago
This is factually incorrect, because AM is incredibly inefficient. AM receivers can be electrically simple, but unless they are well designed and have very large and well-sited antennas, they have extremely poor practical sensitivity. Most clear channel AM broadcasters in the US operate at 50kW during the day; some international broadcasters operate at hundreds of kilowatts. AM broadcast transmitters are large and vulnerable pieces of infrastructure with little or no redundancy that require colossal amounts of power to operate effectively. The amateur radio operators who are preparing to maintain communications "come the bomb" are moving in droves to modern digital modes, because of the huge advantages in weak signal performance - likewise for military and public safety radio. If you want to get a message through in tough conditions, it's a no-brainer to use a highly efficient modulation scheme with error correction. AM receivers are widely available for legacy reasons, but that's about the only thing in AM's favour. https://wsjt.sourceforge.io/wsjtx.html https://wsjt.sourceforge.io/wsjtx.html https://meshtastic.org/docs/introduction/ https://meshtastic.org/docs/introduction/
- cogman10 2y ago
  It's range is largely due to the frequency as well, not the modulation scheme. > it's a no-brainer to use a highly efficient modulation scheme with error correction. And an audio codec with a good ecc scheme on top. You can shove huge amounts of data into the AM spectrum, there's no reason it should be filled with pops and fizzes.
  - geerlingguy 2y ago
    Indeed, HD AM radio worked pretty well, but never became popular, thus stations turned off their HD transmissions one by one.
- nativeit 2y ago
  Depends on your primary goal. Digital signals don’t carry very far without significant infrastructure. “Come the bomb” quadrature encoding will not be helpful for wide area universally accessible communication…but analog signals distributed by transmitters that are still very much alive and active at every radio station (and many emergency facilities and private residences), or that can be made cheaply out of broadly available and very simple components, with wavelengths long enough to get bounced off the ionosphere, and zero dependence on large scale built infrastructure…
greenish_shores 2y ago
Mind the difference between AM and SSB (which may be considered a subset of AM). The efficiency increases with SSB, when compared to usual AM.
- arwineap 2y ago
  I think that ssb is great but it targets bands of radius around you I'm not sure AM has the same issues
  - arwineap 2y ago
    Here's a chart that illustrates skywave bounce 2 MHz 200-400 miles 4 MHz 400-600 miles 6 MHz 600-1,200 miles 8 MHz 800-1,600 miles 12 MHz 1,200-2,400 miles 16 MHz 1,600-3,200 miles 22 MHz 2,200-4,000 miles plus 26 MHz unpredictable during our solar cycle minimum
    - greenish_shores 2y ago
      But of course any of that is completely independent of whether using SSB or not. Modulation used doesn't really change wave characteristics to such significant extent. It's just that SSB is much more effective, this way or another, so it will probably get used in cases like that.
      - hilbert42 2y ago
        "Modulation used doesn't really change wave characteristics to such significant extent," True, except when the ionosphere is changing rapidly and phases change across the bandwidth (as in fading). SSB helps and it's really great for narrow band comms but without the carrier the demodulated audio has pitch problems. Not an issue for basic comms but it is if audio has to be on frequency. SSB reduced carrier and synchronous detection is another solution.
msla 2y ago
The problem is that radio stations typically don't have anyone in the booth most of the time, if ever: https://en.wikipedia.org/wiki/Minot_train_derailment https://en.wikipedia.org/wiki/Minot_train_derailment > The Minot train derailment occurred just west of Minot, North Dakota, United States, on January 18, 2002, when a Canadian Pacific Railway freight train derailed, spreading ammonia gas across the city, delaying rescue operations. The cause was found to be small fatigue cracks in the rails and joint bars, not detectable by the inspection routines then enforced by Canadian Pacific. [snip] > Because it was the middle of the night, there were few people at local radio stations, all operated by Clear Channel with mostly automated programming. No formal emergency warnings were issued for several hours while Minot officials located station managers at home. North Dakota's public radio network, Prairie Public Broadcasting, was notified and did broadcast warnings to citizens. And Minot is one of the bigger cities in North Dakota.
- 15155 2y ago
  Seems like it would not be difficult to pass a piece of legislation mandating some form of registered on-call responsibility for the licensees of these spectrum bands?
  - msla 2y ago
    A lot of things that aren't hard never, in point of fact, get done.
- hilbert42 2y ago
  "The problem is that radio stations typically don't have anyone in the booth most of the time, if ever:" Agreed, it's a serious issue, and the first thing one notices about prerecorded and netwoked programs is the lack of spontaneity and liveliness of the content (personally I don't like stations that are run like this). This, of course, is a regulatory matter. There's no reason why programs cannot be interrupted by an actual human in such emergencies, even if not a professional announcer, an emergency worker or police perhaps.
Zak 2y ago
You've made a very solid case for AM radio continuing to be a relevant technology today and far into the future. I do not, however find that to be a compelling argument for mandating its inclusion in cars. While market forces may be inadequate for driving crash safety, emissions, or fuel economy standards, they seem very well-suited to determining whether cars include AM radios. I suspect the answer will be that most car buyers don't care, and a cheap portable receiver is an adequate solution for many who do.
- hilbert42 2y ago
  It's like this. AM is the lowest common denominator and that's why it's being mandated. There's nearly 100 years of experience of having AM radios in vehicles, it's easy, very cheap and it works. Everyone knows how it work and millions still listen to it. Even if you never use the AM radio in your car someday someone else may do so to get emergency info (it has a much longer range than FM). BTW, most of my radio experience has been in FM broadcasting, so I'd naturally choose that as a better quality broadcast medium. But we're not talking about that here, but rather the fact that AM radio is the LCD for a multitude of reasons. Incidentally, I've also worked on the transmission side of television and I've been involved with spectrum management from a policy perspective. What I've notice in these posts is the tendency to dismiss AM simply because people have become unfamiliar with it given the many media options available today. What people forget or have never understood is that to get that high quality video and sound on your smartphone, or on your widescreen OLED TV requires a huge amount of very complex infrastructure, and it takes many people and many organizations to do so. Only the slightest thing has to go wrong and the whole edifice will come crashing down. An idiot, terrorist and or natural disaster can kill it in an instant, whereas the low tech widely distributed AM TX network is much, much harder to bring to a halt. We saw this on many occasions in WWII, there were many instances where cities were left in ruins but the AM broadcast from those cities were either left intact or gotten up and running again within only a few hours. Again, that's what this whole discussion is about and why AM car radios are being mandated. As I mentioned elsewhere, heaven help us come the next Carrington Event (which it will), none of that lovely media infrastructure will be left standing. Similar scenarios can result for certain emergency situations. When all communications fail then AM radio will be by far the easiest to reestablish, and with millions of cars having an AM receiver that will have services up and running much faster. I know AM is not fashionable but it works and it's easy to establish, same can be said for sewer pipes but we don't chuck them away because they're not fashionable or because they're low tech.
nemo44x 2y ago
My internet was out recently and I realized I don’t even have a radio (or TV antenna) in my house. Just cut off from the world when the internet is failing. I went out and bought a radio in case that awful day comes.
linsomniac 2y ago
If we're going to talk about emergency communications, let's go full send. "Come the bomb", I'm thinking I'm going to want short wave, 10M (citizens band), FRS. Rather than relying on a few huge transmitters, I'm imagining we'll want to make use of the ham radio equipment that is distributed around the world. Honestly, in my 35+ years of driving, I've used CB/FRS way more often than AM.

deleted 2y ago

[deleted]

ben_w 2y ago

> Years ago during a sunspot maxima, I watched a friend of mine located in NSW Australia talk to someone in California on 27MHz AM using only three watts of power (from a handheld CB radio) and using only a whip antenna. This example makes me think that these wavelengths will be heavily congested in the event of a major global, or even local, disaster.

squigz 2y ago
(I know next to nothing about radio) I imagine this would depend on who can transmit "louder"? In the case of a disaster, that would likely be emergency services of some kind
- ben_w 2y ago
  Yes and no; think of a loud room where everyone is shouting because that's the only way to be heard due to everyone shouting.

redox99 2y ago

AM is awful and outdated. The only benefits it currently has, aren't actually related to the amplitude modulation, but simply a property of the reserved frequency bands it uses.

hilbert42 2y ago
"AM is awful and outdated." This, simply, isn't the issue.

jdietrich 2y ago

This is factually incorrect, because AM is incredibly inefficient. AM receivers can be electrically simple, but unless they are well designed and have very large and well-sited antennas, they have extremely poor practical sensitivity. Most clear channel AM broadcasters in the US operate at 50kW during the day; some international broadcasters operate at hundreds of kilowatts. AM broadcast transmitters are large and vulnerable pieces of infrastructure with little or no redundancy that require colossal amounts of power to operate effectively. The amateur radio operators who are preparing to maintain communications "come the bomb" are moving in droves to modern digital modes, because of the huge advantages in weak signal performance - likewise for military and public safety radio. If you want to get a message through in tough conditions, it's a no-brainer to use a highly efficient modulation scheme with error correction. AM receivers are widely available for legacy reasons, but that's about the only thing in AM's favour. https://wsjt.sourceforge.io/wsjtx.html https://wsjt.sourceforge.io/wsjtx.html https://meshtastic.org/docs/introduction/ https://meshtastic.org/docs/introduction/

cogman10 2y ago
It's range is largely due to the frequency as well, not the modulation scheme. > it's a no-brainer to use a highly efficient modulation scheme with error correction. And an audio codec with a good ecc scheme on top. You can shove huge amounts of data into the AM spectrum, there's no reason it should be filled with pops and fizzes.
- geerlingguy 2y ago
  Indeed, HD AM radio worked pretty well, but never became popular, thus stations turned off their HD transmissions one by one.
nativeit 2y ago
Depends on your primary goal. Digital signals don’t carry very far without significant infrastructure. “Come the bomb” quadrature encoding will not be helpful for wide area universally accessible communication…but analog signals distributed by transmitters that are still very much alive and active at every radio station (and many emergency facilities and private residences), or that can be made cheaply out of broadly available and very simple components, with wavelengths long enough to get bounced off the ionosphere, and zero dependence on large scale built infrastructure…

greenish_shores 2y ago

Mind the difference between AM and SSB (which may be considered a subset of AM). The efficiency increases with SSB, when compared to usual AM.

arwineap 2y ago
I think that ssb is great but it targets bands of radius around you I'm not sure AM has the same issues
- arwineap 2y ago
  Here's a chart that illustrates skywave bounce 2 MHz 200-400 miles 4 MHz 400-600 miles 6 MHz 600-1,200 miles 8 MHz 800-1,600 miles 12 MHz 1,200-2,400 miles 16 MHz 1,600-3,200 miles 22 MHz 2,200-4,000 miles plus 26 MHz unpredictable during our solar cycle minimum
  - greenish_shores 2y ago
    But of course any of that is completely independent of whether using SSB or not. Modulation used doesn't really change wave characteristics to such significant extent. It's just that SSB is much more effective, this way or another, so it will probably get used in cases like that.
    - hilbert42 2y ago
      "Modulation used doesn't really change wave characteristics to such significant extent," True, except when the ionosphere is changing rapidly and phases change across the bandwidth (as in fading). SSB helps and it's really great for narrow band comms but without the carrier the demodulated audio has pitch problems. Not an issue for basic comms but it is if audio has to be on frequency. SSB reduced carrier and synchronous detection is another solution.

msla 2y ago

The problem is that radio stations typically don't have anyone in the booth most of the time, if ever: https://en.wikipedia.org/wiki/Minot_train_derailment https://en.wikipedia.org/wiki/Minot_train_derailment > The Minot train derailment occurred just west of Minot, North Dakota, United States, on January 18, 2002, when a Canadian Pacific Railway freight train derailed, spreading ammonia gas across the city, delaying rescue operations. The cause was found to be small fatigue cracks in the rails and joint bars, not detectable by the inspection routines then enforced by Canadian Pacific. [snip] > Because it was the middle of the night, there were few people at local radio stations, all operated by Clear Channel with mostly automated programming. No formal emergency warnings were issued for several hours while Minot officials located station managers at home. North Dakota's public radio network, Prairie Public Broadcasting, was notified and did broadcast warnings to citizens. And Minot is one of the bigger cities in North Dakota.

15155 2y ago
Seems like it would not be difficult to pass a piece of legislation mandating some form of registered on-call responsibility for the licensees of these spectrum bands?
- msla 2y ago
  A lot of things that aren't hard never, in point of fact, get done.
hilbert42 2y ago
"The problem is that radio stations typically don't have anyone in the booth most of the time, if ever:" Agreed, it's a serious issue, and the first thing one notices about prerecorded and netwoked programs is the lack of spontaneity and liveliness of the content (personally I don't like stations that are run like this). This, of course, is a regulatory matter. There's no reason why programs cannot be interrupted by an actual human in such emergencies, even if not a professional announcer, an emergency worker or police perhaps.

Zak 2y ago

You've made a very solid case for AM radio continuing to be a relevant technology today and far into the future. I do not, however find that to be a compelling argument for mandating its inclusion in cars. While market forces may be inadequate for driving crash safety, emissions, or fuel economy standards, they seem very well-suited to determining whether cars include AM radios. I suspect the answer will be that most car buyers don't care, and a cheap portable receiver is an adequate solution for many who do.

hilbert42 2y ago
It's like this. AM is the lowest common denominator and that's why it's being mandated. There's nearly 100 years of experience of having AM radios in vehicles, it's easy, very cheap and it works. Everyone knows how it work and millions still listen to it. Even if you never use the AM radio in your car someday someone else may do so to get emergency info (it has a much longer range than FM). BTW, most of my radio experience has been in FM broadcasting, so I'd naturally choose that as a better quality broadcast medium. But we're not talking about that here, but rather the fact that AM radio is the LCD for a multitude of reasons. Incidentally, I've also worked on the transmission side of television and I've been involved with spectrum management from a policy perspective. What I've notice in these posts is the tendency to dismiss AM simply because people have become unfamiliar with it given the many media options available today. What people forget or have never understood is that to get that high quality video and sound on your smartphone, or on your widescreen OLED TV requires a huge amount of very complex infrastructure, and it takes many people and many organizations to do so. Only the slightest thing has to go wrong and the whole edifice will come crashing down. An idiot, terrorist and or natural disaster can kill it in an instant, whereas the low tech widely distributed AM TX network is much, much harder to bring to a halt. We saw this on many occasions in WWII, there were many instances where cities were left in ruins but the AM broadcast from those cities were either left intact or gotten up and running again within only a few hours. Again, that's what this whole discussion is about and why AM car radios are being mandated. As I mentioned elsewhere, heaven help us come the next Carrington Event (which it will), none of that lovely media infrastructure will be left standing. Similar scenarios can result for certain emergency situations. When all communications fail then AM radio will be by far the easiest to reestablish, and with millions of cars having an AM receiver that will have services up and running much faster. I know AM is not fashionable but it works and it's easy to establish, same can be said for sewer pipes but we don't chuck them away because they're not fashionable or because they're low tech.

nemo44x 2y ago

My internet was out recently and I realized I don’t even have a radio (or TV antenna) in my house. Just cut off from the world when the internet is failing. I went out and bought a radio in case that awful day comes.

linsomniac 2y ago

If we're going to talk about emergency communications, let's go full send. "Come the bomb", I'm thinking I'm going to want short wave, 10M (citizens band), FRS. Rather than relying on a few huge transmitters, I'm imagining we'll want to make use of the ham radio equipment that is distributed around the world. Honestly, in my 35+ years of driving, I've used CB/FRS way more often than AM.