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Why focus on AM when we already have a federally run national emergency broadcast service — the NOAA Weather Radio. Go peruse around 162Mhz. You may find you're

• galleywest200 2y ago
  Where I live we have signs up all over the place near the mountains that tell you to tune into a specific AM station when flashing for avalanche/weather information. I understand wanting to move past some technologies but we are not going to be able to revamp our entire avalanche system _tomorrow_. Most people I know do not have a short-wave radio, let alone one capable of receiving at 162Mhz.
  • tomjen3 2y ago
    Why not broadcast it as FM? Much better signal, much less chance that somebody misses a word because AM quality is shit.
    • aragilar 2y ago
      AM covers a larger area, and is more robust in areas with obstructions (e.g. mountains).
      • TylerE 2y ago
        Yeah, I remember as a kid with a Cheap stereo and an antenna consisting of maybe 5ft of thin wire dangling from it being able to pick up reasonably clear AM transmissions from as far away as St Louis, Chicago, and NYC… and Inlived in almost-coastal NC. Especially at night you could really pull some stuff in. FM by comparison is effectively line of sight, so with a practical broadcast antenna the upper limit is 40 or 50 miles.
        • kragen 2y ago
          the am antenna in your cheap stereo was probably not the dangling wire, but rather a ferrite rod hidden inside the case
          • TylerE 2y ago
            Pretty sure it was the wire, because changing how it was aligned would affect what could pick up pretty dramatically. And I should clarify… while it was certainly a cheap “system in a box”, it was a real multi component system with detachable speakers, etc. not a boombox or anything like that.
      • lebuffon 2y ago
        "AM" is the modulation scheme. A more accurate name for this radio service is used in Europe, "middle-wave". The modulation scheme is not the reason for propagating around mountains and bouncing off the ionosphere at night. The reason for that behaviour is the low frequency used. 540 Kilo-herz to ~1700 Kilo-herz. (I was told once by a young engineering colleague that 1,000 Khz was not RF. :-))) ) So the question is valid. FM could be used in the "middle-wave" band. It would reduce noise but might suffer more when bouncing off the ionosphere at night. (I have read this but never heard FM bounced) The reason FM is not used in the middle-wave band is legacy regulation not technology.
        • ikiris 2y ago
          Fm also takes 10 times the bandwidth of am of that spectrum. The blocks are where they are for a reason.
    • Aloha 2y ago
      Bandwidth in part. AM is more spectrally efficient than FM, and with synchronous AM receivers, you can get noise rejection that is near FM.
    • TeMPOraL 2y ago
      Noise reduction in this scenario would be performed the obvious way - by looping the message.
    • cloudwalk9 2y ago
      I THINK it is FM, narrow FM. My SDR receives some attenuated incomplete-sounding signal when switched to AM on 162.55 MHz even if I widen the bandwidth, and switching to narrow FM gets me the same clarity and volume as my actual weather radio provided I lower the gain a little.
  • ac29 2y ago
    162MHz is VHF, shortwave is much lower frequency (and longer wave). More or less all US car owners already own a VHF radio. Extending it from 88-108MHz up to 162MHz would be fairly trivial.
    • katbyte 2y ago
      Retro fitting all previous car & upgrading all am based equipment is not however
  • gopher_space 2y ago
    > Where I live we have signs up all over the place near the mountains that tell you to tune into a specific AM station when flashing for avalanche/weather information. I live in an area like that as well, and the station broadcasts the same info you see on road signs and web sites. If the lights are flashing it's usually playing "snow tires advised for vehicles..." on loop. the kind of situations people describe where car AM radio is essential feel like corner cases that involve lack of planning and poor judgment or really bad luck. No cell service, no portable radio in your travel kit, no way to stop and ask anyone, and you can't just turn around when you see a flashing sign? It sounds like the plot of a horror movie.
    • katbyte 2y ago
      That’s YOUR area. Plenty around here without any giant flashing signs. Also long 100km bits of highway without cell service Thing about corner cases is they do exist and need to be accounted for
      • herewulf 2y ago
        So, cars in YOUR area should have AM radios? But not every car in existence needs one?
        • 99_00 2y ago
          Cars tend to move around
          • qup 2y ago
            NIMBY!
      • deleted 2y ago
        [deleted]
      • gopher_space 2y ago
        If you actually lived out in the country you'd know that there's like a dozen portable AM radios per household and that nobody ever just guesses about pass conditions. Every scenario people come up with involves a hypothetical hayseed who's almost aggressively unprepared for his situation. This is a problem solved by a $10 Amazon purchase. Why is it such a crisis for you?
  • cloudwalk9 2y ago
    Personal anecdote: that actually saved an important doctor appointment. "URGENT MESSAGE WHEN FLASHING". Well, lights were flashing, guess we could tune to it and hear what it has to say. Sure enough, it announced a traffic jam on our route a few miles ahead that Google Maps vastly underestimated (usually it's been good about that) and we were able to avoid it. Thanks TNDOT. It was because a chemical truck crashed apparently, on our drive back home it was still there with specialized hazmat emergency vehicles around.
• eganist 2y ago
  > Plus, say a nuclear weapon went off anyways and all the FM transmitters died. Is anyone seriously thinking a lone AM transmitter 2000 miles away is going to help? We had all the communication in the world during COVID and that did nothing to stop people from acting foolish. This is an interesting assertion. Many, many people acted responsibly during the pandemic, and in a worst case scenario such as what you described, it's even more likely that a sizable population will gravitate to any source of reliable information. The government is usually the source of last resort for many, many things. Whether it's as a lender (e.g bailouts) or as a source of information (emergency broadcasts), it's at the scope of the nation state where extreme contingencies exist and must be accounted for. I imagine AM radio is perfect for this precisely for worst-cases, e.g where someone might seek to make a crystal radio, but I'd be out of my depth thinking beyond this. I actually was neutral on this until I read your comment and thought it through far enough to reply, so thanks for that.
  • guerrilla 2y ago
    [flagged]
    • TeMPOraL 2y ago
      They obviously meant an emergency scenario, not a slow-rolling disaster that takes generations to play out.
      • lucianbr 2y ago
        Just find some property of any counterexample that puts it in a different category and you never have to admit you're wrong. After all, no two events are ever completely identical, so there's always something to find.
• eimrine 2y ago
  > We had all the communication in the world during COVID and that did nothing to stop people from acting foolish. The government has took away our (the taxpayers) right to move for the sake of some taxpayer's life. How on Earth is possible for the taxpayer to act foolishly? It is his life, if he considers a death as not that important thing to cancel some party, whether it can be considered as foolish? My opinion is that a human has to have a right to get dead, no matter how much taxes the government is going to not take.
  • deleted 2y ago
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• nextaccountic 2y ago
  > Plus, say a nuclear weapon went off anyways and all the FM transmitters died. Is anyone seriously thinking a lone AM transmitter 2000 miles away is going to help? AM radio is simple enough to build with makeshift materials (https://en.wikipedia.org/wiki/Foxhole_radio https://en.wikipedia.org/wiki/Foxhole_radio). You don't need batteries or even a power source at all! (the radio waves themselves can bring power) If civilization had a catastrophic event, I would guess that AM radios would be one of the few surviving technologies
  • SiVal 2y ago
    I would love to see kids given the materials and taught how to build makeshift emergency radios in science class every couple of years. Then they could take them home, stick them in a closet or drawer somewhere, and in case of emergency, they would be everywhere.
    • awful 2y ago
      Now that is thoughtful, and I think, can open the conversation to youth what if, and of what to do in case of... I know as a kid we had Civil Defense, and that funny little CD symbol on the AM dial...
  • squigz 2y ago
    Every once in a while I'm struck by how magical some of our technology seems...
• hilbert42 2y ago
  "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
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  • 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.
• mtreis86 2y ago
  One big problem with FM is that it is selective. If you have two different signals of similar strength on the same frequency you won't get good reception from either. With AM you'd hear both. If one signal is slightly stronger on FM that's the one you'll hear, with AM you'd hear both. For music this is an obvious choice, better to pick a signal than have them interfere, but for emergency communication the opposite is true. It is easy enough for a human to hear two conversations and pick the one you want to listen to by focusing on it - we do this in crowded rooms all the time.
  • idatum 2y ago
    I believe this is why aircraft use AM?
    • the_fury 2y ago
      Yes - this is exactly why aircraft use AM.
• K0balt 2y ago
  NWR depends on thousands of transmitters providing spotty coverage for most of the landmass of the USA. There are large unserved areas, but few people live in those areas. The main problem is that this requires that thousands of radio stations continue to operate, where a single AM station can provide service to multiple metro regions and in many cases cover an entire state. It would be even better if car radios were required to include shortwave / SSB receivers, but there is little mechanism to support the economic ecosystem that would keep those stations viable, and the radios are necessarily more expensive. The long range of shortwave would also open up US listening populations to potential foreign adversaries. AM is a good compromise. AM recovers are cheap and simple, transmitters can be made using 1920s tech, and A single AM broadcast station can have ranges of nearly 1000 miles, sometimes more.
• deleted 2y ago
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• RF_Enthusiast 2y ago
  I completely agree about the value of NOAA Weather Radio. On a related note, the Federal government has primary rights to 1710 KHz, but it's rarely used, and available on most radios. I think three or four high power 1710 stations, synchronized in the decentralized way that WWVH and WWVB are, would be an excellent use of a narrow slice of spectrum, particularly as a way to disseminate information after sunset.