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I'm in the tech industry and I support this.

You can receive AM with very simple receivers. The cost of adding one to a car is miniscule, and it works when other more complex systems don't.

Not only emergency broadcasts but things like https://en.wikipedia.org/wiki/Travelers%27_information_stati... make it important to have a working AM radio in your car.




I’ve heard that some people with amalgam tooth filling can sometimes pick up transmissions and somehow audio would actually play inside their mouth, not static noise, actual voices talking. It’s quite bizarre but also makes total sense when you think about it!


It sounds like it's still on open question as to whether or not this is possible.

This story was the one that came to mind when I say your comment and the post makes for a quick, interesting read.

https://www.snopes.com/fact-check/lucille-ball-fillings-spie...


In this video they can apparently hear the transmission by holding a blade of grass against the transmitter https://www.youtube.com/watch?v=b9UO9tn4MpI

The video looks convincing but it could also be faked, and I don't think it's possible. The signal coming into the radio tower (which is basically just a big antenna) would already be modulated to a much higher frequency (702khz or whatever).

I guess there could be some other effect that makes it audible when you hold a blade of grass or a hotdog to the transmitter, but I don't think it would be intuitive.


"The video looks convincing but it could also be faked"

I don't think it's faked, what's shown here is what you'd expect. I've been on 'live' FM towers and the RF burned holes in my jeans at my knees (my knees were rapped around the metal tower and the induced RF in the tower zapped holes through the material in my jeans and then burned holes in my skin).

On AM the sound that you're hearing is demodulation caused by resistive non-lineararity in the carbon caused by the burning/heating process. This is quite a common phenomenon with high powered AM transmitters.


I've gotten a transmission through my radiator via earth to my computer speakers somehow. With the volume at 0 it still played but was cut when I touched the radiator.

I thought I was going cracy when turning the volume to zero did not cut it before I realized it was radio hehe.

Maybe there can be accidental demodulation somehow?


https://www.youtube.com/watch?v=GHSuInSkHtA

AM is just power, its why crystal radios work...


If you're next to the transmitter, even a wrench can be a receiver. It's a function of power and the am towers put out a shit ton


When there's enough transmitted power, everything turns into a receiver. Besides the infamous tooth fillings mentioned, and the demonstration videos shown around here at the antenna, there's been plenty other reports of things like bedsprings, pipes, and fences converting AM broadcasts into sound.


Unknown to me if that's real, but you can hear AM radio with a sausage of you're next to the transmitter's antenna: https://youtu.be/GgDxXDV4_hc


this is a fantastic demo! just to nitpick, though, it's really the plasma between the sausage and the antenna that's making the sound; the plasma heats up regardless of which direction the current was flowing, so you don't need a 'detector' converting ac to dc as you do in a conventional radio. for fillings the most likely explanation is a parasitic schottky rectifier accidentally formed from a metal oxide, rather than such a resistive phenomenon (though it's not impossible)


You sound a bit credulous :)


The keyword is 'amalgam' - a lead crystal, a bit of wire and a headphone gets you AM reception: https://en.wikipedia.org/wiki/Crystal_radio

(the wire is optional if the signal is strong, and a 'headphone' is anything you can make vibrate with electricity)


I'm sorry but this anecdote sets off my BS detector very hard.


it's probably real but not thoroughly proven: https://www.straightdope.com/21341818/is-it-possible-to-hear...


funny how all of these cases predate the existence of recording devices, probably because people don’t get dental work anymore


plausibly people don't have many such high-powered am transmitters around any more, but also much less dental work is metal now, and the metal is of more consistent quality, so less chance of oxidizing into one of the numerous metal oxide semiconductors in your mouth. it seems to have been a pretty infrequent phenomenon even at the time, one in tens of millions


How on Earth did you arrive at the conclusion "probably real" from that link?


by reading the conclusions contained in the article it links to


That conclusion?

> Whatever the case may be, the available evidence behind this tale appears to be purely anecdotal and not verifiable at this point.


no, the others


I literally quoted the conclusion of the linked snopes article.


the article i linked to wasn't by snopes or on her web site; it was a 'straight dope' column from the chicago reader


Right, "opposed by tech industry" is very broad and all tech doesn't think that.

It's sort of like clickbaiting doctors when they read "doctors don't know what causes obesity!".


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

> 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.


AM receivers can be so simple they don't even require a battery.

https://en.m.wikipedia.org/wiki/Crystal_radio


>The cost of adding one to a car is miniscule.

[citation needed]

There's a Grand Canyon between putting in an AM radio circuit and putting in a fully functional AM radio, doing over the vehicle's EMF, and then making it last for a vehicle's lifetime.


The 70/80's (can't remember) pocket transistor radio from my dad still works.


All I'm seeing is two opposing assertions, neither of which provides a citation. Why should I trust you over OP?


The article has several citations from OEMs on why (PDF):

https://www.markey.senate.gov/imo/media/doc/letters_of_autom...

"Our decision to not support AM radio was primarily linked to our electrification strategy. If Volvo Cars had continued to provide AM radio, our BEVs and PHEVs likely would have experienced EMC disturbances and this could result in poor performance. "


I thought the argument was that adding functional AM receivers to EVs is difficult?


It is. Commenters are not reading the article.


My grandfather, about 100 years ago, built one with copper wire, a crystal he was given by his teacher, and a cylindrical oatmeal box.


If the cost is so minuscule, why not let the market work it out?

Why must all cars have AM radio?


Because like most safety features, AM radio matters most in rare situations that people don't think about when they're purchasing a vehicle. If we let the market work it out we'll find that we lose access to AM radio because people won't notice until they need to tune in to a traveler information station and can't because their radio doesn't support AM.

Then we'll get a bunch of people who are either ignorant of the conditions or who are fumbling with their phones trying to find the information on the internet somehow.

We could phase in a new traveler information system that works in new cars, but that would require an enormous expenditure of resources to roll out the new system and then we'd have to maintain the old one for as long as there are vehicles on the road that don't support the new. It's far more cost effective to just mandate that all vehicles be able to receive signals from our existing system.




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