A controversial bill that would require all new cars to be fitted with AM radios looks set to become a law in the near future. Yesterday, Senator Edward Markey (D-Mass) revealed that the “AM Radio for Every Vehicle Act” now has the support of 60 US Senators, as well as 246 co-sponsors in the House of Representatives, making its passage an almost sure thing. Should that happen, the National Highway Traffic Safety Administration would be required to ensure that all new cars sold in the US had AM radios at no extra cost.
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You can improvise an AM radio receiver with stuff you have lying around your house.
Not only that, it can be powered by the radio signal itself.
https://en.wikipedia.org/wiki/Crystal_radio
A crystal radio receiver, also called a crystal set, is a simple radio receiver, popular in the early days of radio. It uses only the power of the received radio signal to produce sound, needing no external power. It is named for its most important component, a crystal detector, originally made from a piece of crystalline mineral such as galena.[1] This component is now called a diode.
Crystal radios are the simplest type of radio receiver[2] and can be made with a few inexpensive parts, such as a wire for an antenna, a coil of wire, a capacitor, a crystal detector, and earphones (because a crystal set has insufficient power for a loudspeaker).[3] However they are passive receivers, while other radios use an amplifier powered by current from a battery or wall outlet to make the radio signal louder. Thus, crystal sets produce rather weak sound and must be listened to with sensitive earphones, and can receive stations only within a limited range of the transmitter.[4]
It should be noted though that you’ll need a fairly nearby radio station that is transmitting with a whackton of power.
This is just making me think that there should be a fundamentals of modern technology class in high school somewhere between a shop and physics class. It’d be a nerd elective but by fuck am I that nerd
Something between shop class and engineering. Like Technician class. I like it.
Yeah as an engineer I think it would’ve been far more useful than the engineering class I took that was basically how to do autocad and measure things. And it would’ve been useful for everyone.
There are two things at play here. 1) one of the primary purposes of the United States’s education policy is to produce engineers. This is an economic and military strategy. And 2) we live in a world where technology abounds and yet so few people understand it. A robot isn’t a magic person made of metal, it’s the manifestation of the laws of physics as applied for our own desires.
Making a radio receiver and a telegraph and a record and telephone and a basic battery etc makes for more grounded adults. Show the teenagers the way the real world works, clever applications of natural phenomena
A robot isn’t a magic person made of metal, it’s the manifestation of the laws of physics as applied for our own desires.
I suppose if we discovered magic and understood its principles, it wouldn’t really be magic any more.
Any sufficiently advanced technology is indistinguishable from magic.
— Arthur C. Clarke
Well now you’re just where I fell when I learned about the imaginary plane in electronics.
I dunno, maybe we need something more General.
Aren’t you being a little Extra?
He’s just advanced, but you’ll never reach that state these days in afraid.
In today’s world, it’s basically impossible to even start out as a Novice.
You had shop?
lol no I’m a millennial
Shop was the rednecks making explosives in their garages, I was one of them. Mind you they werent supposed to explode.
Considering the growing importance of digital radio communication, Computer-Assisted Design, electronic repair, etc. I’d love to see this kind of thing.
100% accurate, thanks for the clear write up. Please stick it up on Wikipedia if you can :)
And I’ll add a bit about Clear Channel AM (unrelated to the billboard advertising company) - there were originally a handful of said stations that broadcast on a few AM band frequencies that are reserved just for them, so their broadcast range is impressive.
One for example is WOR radio in Chicago.
Fun factoid - you can see on very old AM radios those clear channel frequencies marked by a diamond or similar symbol on the dial.
Holy crap, I have an old radio (a few feet from me) for a decade and I had no idea what the diamond symbols on it were for. Thank you!
See this right here is what I’m on here for, these kinds of connections.
Tell us about ssb. I also just bought an SDR to get my gas meter readings. Any other cool stuff I should check out?
Single Sideband is basically AM 2.0, so to talk about it in detail, we have to take a closer look at good old fashioned 19th century AM.
The graphic above is from Wikipedia. The top graph, the “baseband” signal, is the audio, aka the signal coming out of the microphone. It’s vaguely what a human voice would look like on a specrograph.
The second graph is what AM looks like. The spike in the middle is called the “carrier.” Let’s say you’re transmitting on 5 MHz with a 10 watt radio. When you push the talk button and then say nothing into the mic, you start broadcasting a 5 MHz wave with a power of 10 watts. A receiver tuned to 5 MHz will hear the background static go away, because you are transmitting a carrier wave that does not modulate much louder than the background noise, you are effectively holding the receiver’s speaker still. A signal coming in strong enough to do that we call “full quieting.”
The carrier carries no information. Another way to look at these graphs is, picture the sine wave. You may have seen something like this before:
That middle waveform represents AM, notice how there’s always some squiggles going through the middle, and it varies toward the top and bottom edges? That’s what the upper graphic is representing, that big center spike is always there for that reason.
You may notice that the two lobes to either side are the same shape as the base band signal; or one of them is, the other is a mirror image. We call these sidebands. That’s actually where the audio is. In the second graphic, you can see how the top and bottom edges of the AM waveform resemble the baseband signal. Turns out, AM radio uses twice as much bandwidth and more than twice as much power to transmit the usable signal.
So what if we built the transmitter to only transmit one of the two sidebands and suppress the carrier and the other sideband? The same audio information goes over the air, and we take up less room on the radio spectrum to do it. What’s more, since we’re transmitting less overall “stuff,” the radio’s power is more focused on the part we do transmit, so a single sideband transmission comes across as “louder” than an equivalent AM transmission.
There are some cool upshots to how SSB works: the first is that the radio uses less power and overall stays cooler. AM (and FM) transmit with their full power all of the time, doesn’t matter if you whisper or scream into the microphone you’re putting whatever power your amplifier is set to out to the feed line. You might be transmitting silence, but it is very loud silence. SSB doesn’t do that; the louder you talk into the mic, the more power goes out the antenna. You aren’t constantly transmitting that carrier, so if your mic goes quiet, so does your antenna. Thus, your transmitter gear takes less power, runs cooler, and if you are on some consumable power source like batteries, you can transmit more effective power for longer.
Even cooler than that is the lack of collisions. If you’ve played with radios much, even listening to music radio stations near the edge of their ranges where you can kind of hear both, you know they interfere with each other. Happens all the time with aviation radios, pilots will transmit on the same frequency at the same time and anyone else listening gets to listen to the psychedelic sounds of two carrier waves interfering with each other. On FM radios usually the louder signal “wins” and the other one just sounds like static or interference under it. SSB doesn’t do this.
If two people transmit at the same time on the same frequency on SSB, a third person listening just hears two voices, just like if two people talked at the same time in a room. Hams hold contests to see who can make contact with the most people from the most places, and folks from somewhere rare will end up asking for contacts, everyone else says their callsigns at once like it’s the floor of the stock exchange, the one station will pick someone he heard to exchange details with, rinse and repeat. It’s 1950’s Discord.
Hams also use this technique to send text back and forth extremely efficiently. If you tune your software defined radio to 14.070 MHz (or use one of several people make available online) you might hear what sounds like several strange warbling whistles that come and go. That is PSK31, a digital text mode designed to use an ordinary PC sound card as a modem, and an ordinary SSB transceiver to send the signals across the air. Using software like FLDigi, you can receive and transmit text over the air, and each text transmission is very narrow in bandwidth. Over a dozen can take place in the same space as a normal voice channel, you leave the radio tuned to 14.070 and choose which transmission to listen to by clicking on them in the waterfall, ie choosing what audio frequency to listen to, which only works using SSB because no carrier collisions.
For all its advantages, there are some disadvantages. You cannot transmit “quiet” with SSB the way you can with AM or FM; so the background static, the “noise floor” is always there. Makes it not so nice for listening to music, which is why you basically only ever see it on communication radios. And it also requires a much more complicated transmitter and receiver while achieving the same or slightly worse audio quality than AM. You don’t see SSB used much in VHF and above because there’s so much room for activities/line of sight limits how far your signal goes so the efficiency advantages of SSB are less important, which is why we tend to use FM (or AM for old shit like airplanes) at wavelengths shorter than 6 meters or so.
Man you seem like you’d be awesome to have a drink with and just learn… everything.
Good info here.
Reminds me of that kitchen sink that started picking up AM radio.
Very nice write up. I am curious, is the long wavelength Responsible for the rise and fall in audio quality depending on where you are. I have had this happen as I was driving, the sound quality seemed to pulse.
Also I used to live right at the base of a tall mountain range there was a AM transmitter on the other side less than 100 miles away. During the daytime I could never receive it, at night it would bounce over the mountain and it was pretty clear.
I doubt the wavelength is a factor there; depending on the circumstances it could be anything from atmospheric waves to something in your car causing intermittent interference.
The Earth’s ionosphere exists in several layers. During the day, solar radiation ionizes gas deeper into the ionosphere causing a layer that doesn’t usefully refract most radio waves; you can reach beyond the horizon on some of the higher HF bands, but down in the MF, you’ve basically got ground wave. At night, without the sun around to cook the atmosphere, that lower level dissipates, revealing a higher ever-present layer, and the geometry is right to refract signals for hundreds or even thousands of miles.
Skywave propagation can be really fun to play with.
That truck was a old fucker. It had AM and a 8 track. So I wouldn’t be surprised if the radio shielding was limited and degraded…
There likely was no “shielding” in a truck of that era, just simply the truck was made of metal as was the chassis of the radio, bolt 'em together and you’ve got a reasonable ground.
But, I do know from experience that there are items on a pickup truck that can produce radio interference especially when worn. A worn distributor is a spark gap transmitter, as I learned when I installed a mobile radio in my S10. The audio on my radio got a lot better after a good service of the ignition system.
I have a hard time believing that ¼ of all Americans actively listen to AM broadcasts.
That being said, it’s indispensable for emergency transmissions, and honestly not that complex a component to enable in modern radio systems.
I grew up with a dad who listened to Rush Limbaugh or some conservative jockey (Mike Savage was quite bonkers, still cannot believe he got hired by MSNBC for about 2 weeks before he said some insane racist shit and got canned) on AM anytime I was ever in the car with him.
He’s now a QAnon nut.
I absolutely believe 25% of America listens to AM radio, all the christo fascists and qanoners and magatards on their 3 hour daily commute while they are angry that their kids or ex wives don’t talk to them anymore.
Oh fuck I forgot about that troglodyte. My parents were Limbaugh losers back in the day. Now they’re anti-vaxxers.
He’s now a QAnon nut.
I was just thinking that I hadn’t heard much about Qanon lately, that maybe it had been fading out. No?
Coincidentally, Q posts dried up when John McAfee died. I wonder why that is
I had never heard that before, and that now my truth. It makes so much sense.
Sadly, it has not so much died out as gone more underground, splintered, but still proliferates.
Take a gander at owen morgan’s telltale youtube channel, he actually covers a good deal of this quite well.
He started off as an Ex JW going over online and real world cults, but as QAnon and Covid and MAGA and then Jan 6th all kind of morphed together, he finally dropped his ‘avoid politics’ stance as it was utterly impossible to cover anything related to QAnon without getting political.
Basically, 8kun, Truth Social and other less well known sort of youtube alternative sites and alternative social media sites have just become an alternative reality fantasy land for completely delusional conspiracy theorists and outright fascists and nazis.
Then youve also got a ton of shitty MAGA/QAnon flavored ‘news’ sites (think infowars and breitbart, there are many others) that post absolutely insane nonsense as real, or report on various things leaving out huge details, misrepresenting situations and such.
Their content is then watched and discussed and meme’d and spread on telegram group chats, facebook groups, an increasing number of either online or radio talk show hosts, and by a number of surprisingly popular evangelical preachers, many of whom have basically megachurches as well as their own video streams.
Thats the link that owen came across that kind of led him to be able to figure out how much of the QAnon related mis and disinfo network actually functions, when he discovered a bunch of, again, surprisingly popular evangelical and or charismatic preachers who have decided that basically they are prophets, God literally speaks through them, and Trump is actually the new annointed messiah who is God’s chosen President.
They had made a bunch of prophecies about Trump winning 2020, so when he lost, they basically developed the idea that Trump is actually the President of God’s annointing… as a cope for losing and being failed prophets.
But this idea has stuck, so now anyone opposing God’s President is a demonic force of Satan, blah blah blah.
So… basically QAnon and its derivatives are still going quite strong, they have just largely abandoned platforms that most people know about, or are in largely private groups on more well known means of communications.
I remember seeing one video on one of these youtube alternatives that explained that nuclear weapons are actually fake, dont work, never have, and thus the end of ww2 and the entire cold war and modern day geopolitics are all an elaborate ruse orchestrated to keep us all compliant and afraid… blah blah blah, somehow, its always liberals, democrats, jews and socialists, or secret versions of those, that have been orchestrating a mass conspiracy for a hundred years or something.
We have also had a number of right wing mass shooters, guys that tried to kidnap the governor of Minnesota, and the person who immolated himself outside Trump’s trial… all with QAnon related or derived beliefs.
We now also have certain preachers just outright calling for a christian nationalist government, and they all can be connected to this wider movement stemming from QAnon.
Just because Q has not posted in a while doesnt mean the movement that was sparked and coalesced by and around his garbage has died out.
They just morphed into something else now that it doesn’t have the pull it once did. These nutters are still around and still baking the same conspiracies just without Ron Watkins leaving secret messages pretending to be a government insider.
I had forgotten about Savage Nation until you mentioned that lunatic. He was crazy before crazy was cool.
Same, though my dad was liberal. He just kind of rage listened to these guys. Needless to say, I was young and impressionable and picked up some of their extreme views in my youth, but later got straightened out when I went to college. Fuck AM radio. It is responsible for radicalizing people who spend a lot of time in their vehicles. We should not require it in vehicles. I feel the damage done outweighs the potential benefits from emergency messaging. Everyone has a phone for that these days anyway.
And now you’ve figured it out. This probably has nothing to do with emergency preparedness and everything to do with keeping a propaganda pipeline open. Maybe the D votes are secured by arguing about emergencies, but I just don’t see it.
Recommend people get an AM radio for emergency use, but it doesn’t need to be required for every vehicle.
I have seen the movie, and it is extremely hard for me to watch.
After years of debunking insane nonsense from my Dad, only for him to come up with some new insane thing, then declare he is done with politics, then mention off hand something he could only have possibly heard from some insane QAnon type nonsense, I finally realized he’s an egomaniac incapable of being wrong, doing any self reflecting, who has no problem knowingly lying to those around him, about himself and those around him.
It was very hard for me to realize that though he says he loves me and has attempted to demonstrate this, interacting with him in any way other than coddling his feelings, entertaining his nonsense … just results in him being classic narcissistic asshole.
Better off without him in my life. So, so much less stressful.
Sorry for your loss (even if he’s not deceased, it’s like a part of you dies when something like this happens)
I appreciate your condolences.
There is unfortunately more to it than that… he’s ruined my life more than once, subjected me to insane medical procedures and treatment multiple times as a child, and covered for other family members who have abused me and lied about me…
It took a near death experience for me to figure out that basically none of my family are good people, they’d all rather argue with me than listen or god forbid actually help me in anyway or make amends for the massive mental trauma, physical danger they’ve put me in, financial burdens I now have from going along with their plans or advice and then that all going to shit because none of them can plan anything or be any kind or reliable.
Oh well, I guess.
Fuck, dude. Sorry to hear and glad you got out. Hopefully you’re doing well.
I’m not, but I am slowly on the mend.
I know that back in the early 00s I was traveling cross country and was surprised when I reached the prairies and realized there were way more AM than FM stations, but it’s because AM travels much farther even though the fidelity is lower.
even though the fidelity is lower.
That’s the trade off you make with AM. With just about all wireless transmission techs, really. There seems to be an inverse relationship between range and bandwidth. If you want one, you sacrifice the other. Compared to FM, AM radio leans more towards max range, so the audio quality isn’t quite as good, but it goes for miles.
And thats how you get all the people living in rural America who listen to AM nonsense talk radio.
Its also much, much cheaper in general to start your own AM talk show because of the relatively lower costs compared to FM broadcasting, so any crazy angry idiot can do it.
l’d think that the Internet (well, systems built on the Internet) has probably been the most-influential system for lowering the bar to transmit ideas in recent years. I mean, it’s really inexpensive and easy to post on social media, and that can reach a whole lot of people.
True, I agree.
In the past, AM radio was a much bigger piece of the pie in terms or right wing nonsense extremism vectors, and now it is still an important segment of it, but yeah the internet is certainly much more important overall these days.
A lot of EV auto makers have been arguing that the frequencies that some of the electrics in the cars run at interfere with AM radio reception.
Not sure if that’s a legitimate argument or they just don’t want to pay for extra shielding to block out the noise.
Sounds like they are admitting that their cars violate FCC rules about interferance.
It’s more about internal electrical noise. Cars have always been electrically noisy environments. There’s a chunk of questions on the ham radio technician exam about dealing with having a radio in your car.
EVs just happened to affect regular AM radio.
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If only there were some way to selectively place an antenna.
A lot of sports radio, npr, and conservative radio stations are on AM. I listen to two of those three, though most the stations I listen to have an app or streaming option I use more often then actual radio.
Didn’t realize like 10% of NPR stations were still am.
I have never encountered an AM NPR station. Where do they have those?
Found this list, and they’re surprisingly spread out across the county.
(There’s 57 of them on the list for anyone that doesn’t feel like clicking)
Interesting. Thanks.
Edit: Makes sense that Alaska has several considering AM’s range.
*than
I usually flip through AM before FM if I’m reduced to using radio.
Besides that, it’s a layer of redundancy in our society in times of emergencies. There’s no good reason to do away with it.
The average American is 38.x years old. There are a lot of children, but the olds still run this country. China is around 37, Germany is around 39. I don’t think that 25% of America listens to AM broadcasts on a regular basis, but I do think at least 1/4 of the population thinks it should still exist.
I was referring to a quote from the article where someone stated that 82 million Americans listen to AM radio.
Coincidentally, I am above average, think that AM radio has utility, and am not opposed to requirements that it be made available in car stereos - though I do not actively tune in.
I’m opposed to it, if the argument is basically “for emergencies”… then putting an emergency radio in would be better. At that point, just lump into the spare kit or something.
Nobody in an emergency is going to think to use something that they don’t use in every day life. Having AM radio in cars is… not going ti be useful. (EAS goes out on FM amd say radio, too, and there’s the WEA sent to cell phones for people younger than dirt.)
and if SHTF, powering a car is going to be difficult. You basically can only rely on the gas in your tank and what you keep around for the lawn mower (if that.).
Most emergency radios are designed with minimal power from the get go (ie battery operated, recharged via hand crank or portable solar, etc.) and can usually be set to automatically come on if the EAS sends an alert.
The justification of “emergencies” is problematic. Most people aren’t going to hunt for an AM radio in an emergency. They are going to their phone/computer. If they want to prop up traditional communication then they should just require both AM and FM AND require the EAS included. With software defined radio this all can be implemented with a single chip and SiriusXM included probably. Just requires the appropriate antennas.
I’m just going to assume there’s somebody that makes a single part, it’s all they make, but it has to go into every am radio; and that person paid off a bunch of lobbyists so they can keep selling that part.
It’s stupid. For emergency alerts, cell phones are vastly more useful, the Wireless Emergency System is far more featured, cell phones are likely in everyone’s pocket, and the system is as reliable as the EAS is.
Any other justification is stupid, and propping up AM is probably the result of said lobbyists…
All of the comments like these don’t understand the word emergency.
There are numerous plausible reasons cell phone towers, computers, and TV will be out in a true emergency.
I mean, hell, cell phone were unusable on 9/11 due to congestion, and even though it was a horrible event, it want an emergency the like of which are possible.
AM is dead fucking simple. Seriously. If you know what you’re doing, you can make a receiver with a wire, a resistor, and a speaker. You don’t even need power to run it.
The WES system that sends broadcasts to cell phones is more like a pager than cell phone. On 9/11, a WES signal was never sent given the extensive media coverage.
The fact that you mention two way communication getting blocked during 9/11 as an argument for a technology that doesn’t allow 2-way communicatio… is kind of amusing.
There is a further, critical advantage to cells. The vast majority of people wouldn’t have to build a cell phone to get that alert. Pretty sure the only am radio in my house is an unplugged and stored hand crank emergency radio.
We all already have phones in our pockets, or at least in arms reach practically 24/7. The hardware to maintain the network already exists and is going to be maintained regardless if it’s used for alerts.
AM is largely going away. There’s only a handful of niche uses (like very rural or remote locations,) where it’s more useful.
To further expound on that…. Are you running your car or truck or what ever 24/7 in case of an emergency broadcast? In an emergency it’s best to have your vehicle be a dedicated vehicle and your receiver a dedicated receiver. You don’t want to find your battery ran down or that you’re out of fuel.
Which brings us back to… this bill is stupid. Unless you’re a trucker, you’re probably not going to be around your car enough to reliably get the emergency broadcast.
And truckers have better systems than AM radios for communication.
Your phone ain’t gonna be much use when there’s no tower nearby.
Neither is that radio.
What’s your point?
AM is used for traffic advisory and weather conditions by state dots. A car without an AM radio cannot receive those safety critical broadcasts. An AM radio should be required equipment on every vehicle.
AM radios are also incredibly cheap and simple. It’s just one more source for a digital stereo system connected to a fairly simple circuit. I doubt this costs more than $5 per car to implement.
Oh my god, we’re gonna have to increase the cost of cars and trucks by at least 8000 dollars to cover this egregious and unfair regulation! - Automotive CEO.
Just layoff the entire radio team and the Chief Communications Officer. That’ll teach them to fuck with the Chief Head Honcho.
AM radio costs nothing to implement, that’s not why it’s absent from me cars. Many modern cars use some form of brushless motor in the power train. The inverters for these motors work at a frequency that interferes with AM radio reception at close range. Manufacturers can add it back to cars (probably by an over the air software update as many radios are SDR), but it’ll just pick up whistling when the car’s moving.
Yeah that sounds important
The argument for AM appears to be: the vast majority of adults will receive an emergency broadcast through their cellphone, but what happens if some event has already occurred which disabled large portions of the cellular network (which itself is an obvious target to create havoc)?
I’m fine with using AM as a redundant system for alerts.
Maybe make it more useful though for people in the car? I don’t need an AM button I’m never going to touch. Instead have it monitor whatever the emergency broadcast frequencies are automatically, and put something on screen when there is an alert. That would make it a useful “modern” feature as opposed to appearing as a legacy holdover.
I haven’t been following the situation, but it sounds like we haven’t even really managed to get terrestrial digital broadcast radio functioning all that well for audio. Things have kinda fragmented into three separate standards (HD Radio in the US, and Digital Audio Broadcasting and Digital Radio Mondiale in Europe).
I think that if it’s going to reach the point of mandating inclusion of newer radios, it might be preferable to sit everyone down and come up with some kind of broadly-acceptable single standard before we start baking it into legislation.
Also, if we’re gonna have a way of talking to the car’s computer remotely, for displaying alerts or whatnot, I’d rather that the protocol be cryptographically-secured from the get-go and that the modules be hardened as best we can. I don’t really want to deal with little Jimmy with a $10 USB radio and a laptop dicking up autos at scale.
There isn’t a way to do it, digitally. It’s all radio waves. The lower the frequency, the longer the wavelength, the less information it can carry, but the longer it can travel and get picked up on an antenna. AM operates and can have audio heard/understood at a much lower frequency than a digital signal. AM operates in the KHz range. FM is in Mhz, and digital radio operates in Mhz, as well. Specifically, digital radio is broadcast at around 175Mhz, on the low end; while AM radio is around 1,000 Khz.
Thing is, it takes 1,000Khz to equal 1Mhz. That means that digital radio signal is flinging out data around 175 times more than the AM frequencies could, so it can’t reliably transfer nearly as far. There’s also a hard line on digital signal interpretation. Once there’s a threshold hit for not picking up enough signal to fully interpret it, you drop straight to getting nothing interpreted. It’s like how now that all tv signals are digital, so you either get a picture that looks perfect, or you get nothing. Back in the analog days of television you would often get fuzzy pictures and audio. The TV was able to interpret whatever signal it did manage to get, even if it wasn’t all of the signal.
AM operates and can have audio heard/understood at a much lower frequency than a digital signal.
Specifically, digital radio is broadcast at around 175Mhz, on the low end; while AM radio is around 1,000 Khz.
HD Radio uses the same frequencies; that’s a selling point.
https://en.wikipedia.org/wiki/HD_Radio
HD Radio (HDR) is a trademark for an in-band on-channel (IBOC) digital radio broadcast technology. HD radio generally simulcasts an existing analog radio station in digital format with less noise and with additional text information. HD Radio is used primarily by AM and FM radio stations in the United States, U.S. Virgin Islands, Canada, Mexico and the Philippines, with a few implementations outside North America.
The term “on channel” is a misnomer because the system actually broadcasts on the ordinarily unused channels adjacent to an existing radio station’s allocation. This leaves the original analog signal intact, allowing enabled receivers to switch between digital and analog as required.
There’s no lower limit to a frequency that contains a digital signal. Submarines use the VLF range and do digital communication.
Any frequency that can transmit an analog signal can also contain a digital signal.
The reason you’d want to use a digital encoding is that it can more-efficiently encode the useful information than an analog AM signal.
AM radio uses a really simple encoding. It’s the analog analog (heh) of PCM, which is what a simple WAV file on a PC uses.
But that’s not actually optimized for a human hearing system, and it’s why we don’t usually use that encoding for most audio transmission today.
PCM is good at encoding whether one sample is suddenly high or low. But…we can’t perceive that. Our hearing system doesn’t pick that up well.
A lot of lossy compression we use – JPEG, MP3, and it looks like HD Radio and the other two – represents data using a discrete cosine transformation (DCT) to obtain data in the frequency domain, as a bit of information in the frequency domain buys more information that we can perceive than PCM.
There’s also a hard line on digital signal interpretation. Once there’s a threshold hit for not picking up enough signal to fully interpret it, you drop straight to getting nothing interpreted
That’s not a requirement of a digital encoding. You can create encodings that deal poorly with interference, but you can also create encodings that deal very well with interference.
If I LZMA-compress my data, loss of a single bit in transmission may result in multiple bits not being recoverable.
Raw PCM is pretty resilient to a single bit error. A bit of transmission lost probably isn’t even perceivable to a human, just because PCM isn’t a very efficient encoding for human hearing.
But I can make an encoding arbitrarily-resillient to interference by using forward error correction to provide redundant data that allows reconstruction of the original data if there is an error in transmission.
Now, that requires more bandwidth, which may not be the tradeoff that I want to make…but using an encoding other than PCM for the audio frees up bandwidth. So if I want to, I can use the bandwidth made available to pack more FEC data in. I can come out ahead in terms of interference resillience if the encoding is an efficient representation.
Single-bit errors aren’t the only type of error out there, and if you know something about the type of interference, you can maybe improve on that – like, maybe you’re more likely to have a run of errors, so you don’t store error-correction data near the data that it’s correcting for. Or maybe I can expend more of my redundant data on more-perceptually-important bits in the data; you can permit for gradual degradation via such a route. As you hit some error rate X, you will be less-likely to be able to reconstruct the more-perceptually-important bits.
The TV was able to interpret whatever signal it did manage to get, even if it wasn’t all of the signal.
ATSC will also be able to show a degraded TV feed – it’s not a flat threshold at which it just cuts out. You’ll start having visual and auditory artifacts, see discolored squares and such.
You definitely can make a digital protocol which is less-resillient to interference than a given analog protocol. But that’s just a matter of the tradeoffs you want to make. That includes how much frequency spectrum you want to allocate to it. What’s important to get correct in the reproduced audio – if you want to reproduce audio for a modem rather than a human listener, then encodings designed for the human are going to do poorly. What the characteristics of the interference you expect to see are. What kind of fidelity you want in a low-interference environment.
Now, that doesn’t mean that a given digital protocol has made the tradeoffs that you want for a particular scenario. But it can.
Also, anything cryptographically secure will be reverse engineered in a few years. If the keys have to be cycled, then all old radios will no longer work.
Loads of examples of DRM being broken (iPhone jailbreaks, Nintendo switch emulators).
How long were DVDs around before they were cracked? 2-3 years?
Nintendo switch emulators came out a year or so after the switch was released.
I disabled the emergency alerts on my phone because my provincial govt was using it like their personal Twitter account, and I can’t stand listening to the radio. I guess I’m going to find out when the tsunami just rolls over me.
I felt bad doing it but had to do the same for the AMBER alerts. Maine got me a few times with child abductions at 3am. Spoiler it was a domestic issue and the abductor was a family member every time. Kids were fine.
Great, another good thing ruined by twats
but what happens if some event has already occurred which disabled large portions of the cellular network
As someone who has worked as a technician in both broadcast and cellular, I can absolutely confirm that cellular networks are a lot more fragile than any type of traditional broadcast, and that AM is much more robust than any other form of broadcast.
The transmitters are so much more simple devices, and are much easier to repair with limited resources than FM or television, should the need arise.
Lol. “Proponents claim it will reduce electric vehicle range”. What a fucking joke.
Here’s the thing about AM. Especially during any disaster. Damned near everything can get knocked out, power wise within 50 miles of you. At that point, you have no cell service, no data, and no FM radio. But AM? AM operates at a lower/longer frequency band. It can reach over double what FM can, and much further still, at night when it’s signal can actually reflect off the ionosphere. Hundreds of miles.
So if shit ever REALLY goes down, AM radio is the most usable form of spreading information across the country. Bombs, freak accidents, mad scientist doomsday device, war, floods, tornados, etc. Anything that knocks a city out on power, AM will give you that information you’ll need about where to go and what to look out for.
So the argument is… When a bomb knocks out everything and basically all infrastructure, we need to make sure the Teslas and other pure electrics have integrated AM radio? So they can’t charge and can’t use the device in the situation you specifically describe, but definitely NEED it by law the rest of the time?
Sure I guess.
Maybe if this is the purpose we mandate every new public library or other public space provide free access to AM radio receivers.
How about a tornado? You see the weather got green so you switch to am radio because that’s how you hear about the weather which is drastically important that you know immediately.
How old are you? You open a browser and look at live Doppler. If the power is out you’re in the shit already and should shelter in place but you use a phone in that case same purpose.
Nobody hears the tornado siren and goes “Jesus Christ, Mabel! Go to the car for the AM radio!”
If I’m driving? I know to switch to radio. Especially if I’m in bumfuck nowhere. Especially especially if I’m in Appalachia where the mountains fuck with cell service and fm, but leave am fine. Sure I’ll have to hear a sermon, but I know it’s the emergency broadcast medium of the United States federal government. Also vehicles should have it in case cell service is down. In case your phone is dead. In case you forgot your phone. In case a lot of shit happens because I know if all else goes wrong the feds are broadcasting on AM unless things are ok.
I’m 29.
I think a great option for you then is to buy a car with an AM radio or to just, idk, buy an AM radio. I myself am getting out of the car at the earliest possible opportunity in that situation. But as a plains dwelling EV driver who is mostly at home, this is something of a fantastical edge case.
If you don’t have a radio and you regularly need it or anticipate it will be your lifeline, it sounds like YOU the consumer made a mistake.
And I think it’s fair for my federal government to demand all vehicles have emergency access to their emergency alert system. Like that’s what we’re talking about here. A dirt cheap system that takes basically no energy to maintain compatibility in an industry that’s infamous for its willingness to kill its customers for a buck.
Now if we want an emergency band that it’s allowed to mandate sure. But honestly as a nice to have, fuck it make the bastards throw in an fm too.
There’s places with no cell coverage and solid AM/FM radio coverage
And AM travels twice as far as FM.
All auto manufacturers were planning on going “no AM” and “today’s” amount of AM radios isn’t much of a problem, but 20 years down the line it very much would be.
Also, the entire reason for manufactuerers wanting to drop AM is just to cheap out on $5 worth of electric shielding.
I guess I still just don’t buy it. I am not buying a car for emergency preparedness purposes and don’t ever use the AM radio anyway. Sure yeah maybe AM is the way in a disaster, but why is the onus on cars? It’s like arguing that you can’t eliminate a cigarette lighter because then you couldn’t heat canned food or you have to have bench seats so there is a place to sleep in a disaster. Required AM for cell phones makes more sense than requiring it for cars.
Cell phones can’t do AM/FM radio signals very well. Antenna is too small. Back when cell phones had radios built in, the headphones cable doubled as an antenna.
Plus, people who need travel or power when all power is out, go to their cars.
So no. Cell phones aren’t capable. Also, cigarette lighters were totally incapable of heating food. A half inch coil of heat that stays hot for all of under two minutes isn’t going to heat your can of beans.
You sound like one of those fools who’d build a house below the tsunami warning signs because their hasn’t been one for over 30 years.
One tool one job dude. You want to mandate people have an AM radio, then make that the rule. Or a generator, or a stove or whatever. A car doesn’t need an AM radio. It is standard because it was historically common, it is not needed by most people except as a tool to serve them shitty right wing and religious talk radio.
Get off you short and weird fucking soapbox. And if I sound like a tsunami builder you sound like a doomsday prepper: get your guns, 6 months of food, and iodine tabs for your family to the vault straight away instead of commenting here.
It is more like say some kind of disaster destroys a local/regional power grid. It could take weeks or maybe months to restore power. Those big transformers are built to order and normally power companies order them 2 years out.
This would disable most if not all other forms of communication. Local FM is out, cell towers go down, and the local Internet is unpowered hell local newspapers couldn’t even print a paper. An AM radio station outside of the area could easily be used to transmit important information to the whole area. This was more or less the plan during the cold war if there was a limited exchange of nuclear weapons. Yes a large exchange of nuclear weapons or a nation wide EMP burst would disable AM too, but at that point there is likely no longer a functioning government to send out information.
Was the plan during the cold war that we had to get in our cars to hear said message? I don’t take issue with AM, by why does it need to be standard in every vehicle and not in public spaces or cell phones or clock radios or something else?
Not necessarily back then more or less every one also has a home radio which often could be run on battery. But the car provided an independent power source that was removed from the grid. For most of the cold war cars were purely mechanical no micro chips to fry. Also vacuum tubes were a common thing which are much more resistant to EMP.
For cell phones, kind of a space issue. Like, they’re already trying to use all the space inside the case.
The equipment on an AM radio transmitter is also more robust and is more likely to survive an EMP blast.
Requiring the installation of analog AM radios in automobiles is an unnecessary action that would impact EV range, efficiency and affordability (says the lobbyist)
Oh no the vehicle when driving at speed now uses 10001 watts with radio on instead of 10000 watts. Efficiency and range is ruined.
Also the $60k luxury vehicle is now unaffordable when a $1 am receiver is added in the infotainment
The problem isn’t the energy use nor the cost of the am radio, it’s the amount of shielding and other changes that need to be made so the motor and inverter don’t interfere with the am signal. On my bolt there’s an am radio, there’s some ‘stations’ that I can hear the actual sound of the motor.
If standards aren’t set and enforced for that shielding, it won’t just be radio in cars that don’t work. That RFI travels like a tiny broadband (as in multiple frequencies) radio station… because it is. The impacts are compounded the more cars are like that.
The only thing that’s even slightly complicated is antenna placement, all the components are cheap
The right-wing hate talk radio protection act.
If they oppose it then I’m generally for it, sounds like AM Radio is used to broadcast safety messages on some roads in the USA so it makes sense. Plus, Radios are run of the mill common so it’s not like it’s any sort of barrier to entry.
AM’s lack of fidelity allows it to have increased range, so it’s especially important for emergency situations.
It’s more the modulation type and lower frequency that allows the signal to propagate further. Hilariously, HD radio exists in the AM band in the US, digital transmissions over AM that sound crystal clear. I say hilarious because it seems like it doesn’t make sense but then you have clear audio from something that can be affected by turning on a light, but simultaneously can transmit 6 states away to a little device in your hands without the aid of satellites.
Edit: Although, it really seems that rolling out a new emergency broadcast mechanism would make more sense, I suppose they’re trying to ensure the least common denominator exists across all existing vehicles, since one from the 1930s to the 2020s could receive an AM transmission. Much like how aircraft still have AM radios for voice communications. Unless the AM band in the car is always listening for emergency broadcasts though, adding it is useless, as few would actively listen to it.
Was about to ask if we can transmit digital signal with enough compression and error correction over AM - I guess I wasn’t the first one to think of it 😂.
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No worries. You don’t understand how radio transmission works. You’ll learn though. It’s crazy cool.
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Do cars really need to have it though? They seem to be the only thing “targeted” to be forced into include something that can receive emergency broadcasts. Why not force homes to be outfitted with an AM radio? Everyone lives somewhere (mostly, unfortunately) but not everyone owns a car. If they really want people to have access to AM radio emergency broadcasts maybe they should supply people with portable AM radios rather than forcing car companies to include it in their cars and increasing the price of vehicles since they will require larger antennae and more wiring than just FM radio or no radio at all.
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What if, instead, we eventually phase out AM radio broadcasts and reclaim the frequency for other purposes?
AM Radio has an extremely important role in emergency broadcasting, because you can cover a whole continent using just 3-4 broadcasting stations, and it is so easy to demodulate, that you can build completely analog recievers that need no power source (they use the carrier wave as a power source). This also means that AM receivers are very cheap, so in a lot of developing countries the only broadcasts most people can afford, and will reach them are AM.
I think we should keep AM radio around, at least for emergencies.
Also, unfortunately, when HF bandwidth gets freed up, it mostly ends up going to companies that use it for high frequency trading, and not to things where it would benefit the public, like ham radio, or digital broadcasts.
No.
Enough analog broadcast spectrum has been destroyed for almost nothing.
I still can hardly believe they wiped out broadcast tv signals for . . . What did they do it for again?
Additional channels. Higher definition content. Widescreen support.
I still can hardly believe they wiped out broadcast tv signals for . . . What did they do it for again?
Wiped out what? I can still get OTA TV with an antenna.
A digital antenna?
No, the exact same antenna I was using for Analog TV.
You may be near a station that still broadcasts analog but I thought the clock ran out on that.
Analog TV is no longer broadcast. It’s digital only.
I am receiving HDTV over the air with the same antenna I used to receive analog TV.
Ah okay, but the TV is doing the conversion then. That’s what was confusing.
Yeah let’s keep flooding old noise into the airwaves rather than update just so you don’t have to acknowledge you’re getting older and the world is changing.
Go use a 14.4 baud modem if you like obsolete communication protocols so much.
fr fr no cap fam
As someone who has minute knowledge of how radio works, what could those frequencies be reclaimed for?
I also don’t have much knowledge here, but I don’t think much.
I guess the wavelength differences on HF and below would be too large for something of larger bandwidth. And anyway, the AM broadcast bands aren’t that large anyway. Plus there would still be too much RFI from foreign broadcasts.
My idea is, it could perhaps be upgraded to DRM. But this is used very rarely since it requires DRM-compatible receivers.
But personally, I don’t think this would be a better idea than AM. Having to get new receivers for over-compressed digital audio? Nah.Second, probably not the best idea, some of those could be license-free bands. E.g. for LoRa. Imagine Meshtastic on HF.
My understanding is that the EU – higher density, more languages (so more radio stations that nearby people can’t use), more-congested radio spectrum – has done this, forced a switch to digital car radios, and has generally placed more weight on ways to acquire more usable bandwidth.
The US, without the same level of pressure for the frequency spectrum, has placed a higher priority on not breaking compatibility, keeping existing devices continuing to function.
https://en.wikipedia.org/wiki/Digital_Audio_Broadcasting
In the European Union, “the European Electronic Communications Code (EECC) entered into force on 20 December 2018, with transposition into national legislation by Member States required by 21 December 2020. The Directive applies to all EU member states regardless of the status of DAB+ in each country. This means that since the end of 2020, across all EU countries, all radios in new cars must be capable of receiving and reproducing digital terrestrial radio.”
Glad they have their fucking priorities straight. Cars are growing at an insane rate and becoming more dangerous to operate but at least they will have garbage AM radio.
Fuck congress
AM radios are incredibly cheap and simple, and they’re the primary means of communicating traffic and weather information.
Should note that they also don’t cost anything to receive information, unlike digital data services. So as long as your car has power, it’ll have a radio receiver. This, unlike mobile internet, which can cost in the neighborhood of $50-150/mo for the same access. And which don’t work in rural areas with poor wifi coverage.
It’s also one of the most reliable ways to transmit data wirelessly. Huge range, pretty landscape durable. Only problem is the sound quality isn’t good enough for much music. It’s a safety feature for certain
Til am radio is still a thing? I know lots of fm radio stations but always wondered why every radio has an am setting, while there is no am stations available.
In some places you’ll see those giant electric warning signs over interstates.
And some times they’ll say “tune to AM 84.2” or whatever, because what drivers need to know can’t be read off a sign.
Ah, good, I assumed it was just for Church Broadcasts or something, but the whole safety requirement makes much more sense. Sucks for the hearing impared, though.
The popularity of AM has declined greatly, so license purchase for religious and crazy alt-right broadcasting can be had on the cheap.
Sometimes I flip to that while traveling just for fun. Has a kind of spooky feeling.
AM radio is also used for time keeping and weather transmissions for embedded systems that don’t need Internet or heavy computing power (like a clock on your desk or a watch). It’s also good for emergencies. All of which can be passed in analog audio or digitally modulated (or both). Probably not exciting for music, but the fact that it’s there and you can tune into it to find out the weather or traffic is useful.
I don’t think I’ve ever heard an AM transmission in my life, is there a benefit relative to FM or digital radio?
Range is the biggest. KMOX in St Louis was known to reach Colorado from my understanding. There are/were a lot of Cardinal fans because of it in that area before they got the Rockies. I don’t think they broadcast as strong now, not sure. FM will cut out in under 75 miles* unless you have a “good” antenna.
*Not sure the proper range.
And at night the way the signals bounce they can be heard for a thousand miles or more. Due to interference only some stations can run full power at night while most have to turn off or turn power way way down.
Occasionally it can be heard across continents even
In emergency situations the benefit is range. You can broadcast further and reach more areas with one station.
AM stations have to cut their power to like 10% (often even less!) at night, it’s wild
some am stations go dark (off the air) at night, even. there’s a ‘daytimer’ near where i am. it’s weird.
I think the longer wavelengths of AM transmissions travel a lot farther, and are less prone to scattering, but that’s about it. FM allows for more information density (you can broadcast in stereo, for example), and is less prone to the static that plagues AM radio. That’s why AM is mostly talk stations, and FM tends to be mostly music.
The AM band is the strongest of the two. Some countries however have made AM illegal to use in consumer vehicles, because it is used by military and state.
i thought all cars already have am
When did they stop?
