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Comment by htgb | Hacker News Reader

My main issue with deprecating FM in favour of digital radio is its use for emergency broadcasts or in war. Not because of the protocol itself, but because of adoption: almost everyone has a working FM radio available, but few people buy dedicated radios that support digital radio. I would guess that new cars is the main source of compatible receivers.

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Norway has a nationwide network of warning sirens that was built out during the cold war and that is tested regularly that could be used to convey a wider range of critical messages without the need for a radio receiver (during my childhood we heard these very regularly, but with the collapse of the Soviet Union, the test frequency was reduced significantly and now they're only tested twice a year).

However with the rise of the internet and decline of the printed phone book, which used to be distributed to absolutely every household, and that listed the (small) set of warning patterns the sirens would use (that included e.g. warning about air raids), they've now reduced it to only one signal to avoid depending on people to remember them:

"Important message - listen to radio"

...

I wonder how exactly they'll resolve that with a diminishing proportion of the population having "radio" that's independent of internet access being up.

I've only realized now how odd this is: Boulder, co is one of the safest places in the United States (crime and natural disasters), but they test the super loud warning system every monday during the summer.

These days they're mostly used to warn about tornadoes, which Colorado ranks #9 in the nation for.

..and guess how this system is activated? Using traditional FM (some form of RDS, I think). Which is why not all the transmitters have been turned off yet.

This was true a decade ago. After several moves, I no longer have VHS player, Floppy disk drives, CRT, or radio. The only am/fm raidios are in our cars. If anything AM should be kept on, as you can broadcast farther on lower power or we should get younger generations into ham radio.

>If anything AM should be kept on, as you can broadcast farther on lower power

And receivers can be built with extremely simple parts so for the war/disaster situation it's a hedge against the complexity of our technology stacks.

Actually you can build a simple FM receiver with the same parts you would use for a simple AM receiver, if you are willing to accept a fair amount of distortion. It would not be great for music, but would be OK for receiving news or weather or emergency instructions.

One way to do this is to use something called an "FM slope detector" [1]. The idea is that you have a tuned circuit tuned to slightly above or below the carrier frequency of the FM signal. As the FM signal frequency moves around, it also moves nearer and farther from the center frequency of the tuned circuit, which means the output of the tuned circuit rises and falls. The result is that the frequency modulation of the FM signal gets turned into amplitude modulation of the output of the tuned circuit.

You can demonstrate this if you have one of those cheap SDR dongles. Tell your SDR software to decode as AM, but tune to an FM broadcast station, and then start slowly moving the tuning up, and you'll find a point where the broadcast becomes quite intelligible.

[1] https://www.electronics-notes.com/articles/radio/modulation/...

On the transmitting side, there might be advantages to medium wave am for coverage compared to FM on 98/108 MHz. In the UK on long wave we have (or pehaps had) basically one large transmitter covering a large percentage of the population.

https://en.wikipedia.org/wiki/Droitwich_Transmitting_Station

Except here in Belgium, they already switched off DAB in favour of DAB+. Now everyone can go out and buy a new radio again.

Meanwhile, they also rally against planned obsolescence. How's that going to work?

(luckely, they haven't yet switched of FM, that's scheduled for 2020)

Same story in Norway - first they tried very hard to push DAB receivers, and I, being a firm believer in radio over TV for mass communication duly bought DAB radios for the car, kitchen, bathroom, living room hi-fi - then they (in fairness, very sensibly) switched to DAB+. Off to ye olde electronics shoppe I went again.

I wonder how long DAB+ will last; I expect that sooner rather than later it will be scrapped for streaming via cellular networks - because doing so will be cheaper still than operating a DAB network.

Sigh.

The problem is that the average age of the engineers that have knowledge of high power AM at LF/MF/HF is probably well into the 50s and some of the actual transmitters are not far off that either.

You might really enjoy this blog, then. The author has been watching both the decline and advancement of radio of the last few decades. It was interesting to see these big-iron transmitters being replaced by half-a-rack of solid state gear, but then still taking up four racks because of all the other gear.

His last post is poignant, though: "...the absolute soul crushing mediocrity of automated programming is killing the entire industry."

http://www.engineeringradio.us/blog/

Radios are still sold in stores. Also, Phones and MP3 players often have FM radios. Heck, my best radio is probably my OP-1 synthesizer.

The real "magic" of FM radio that it something that Just Works. You don't have to pay, you don't have to connect to some network, and it's something that worked since late 1930s. No matter what people say, any current digital radio formal will almost certainly obsolete in less than 20 years.

How do you like your OP-1?

Love it. It's one of the most well-designed electronic devices I ever owned. Rally fun to use. I think it's worth studying as an example of great user experience and designing for "emergent" features - even if you don't care about synthesizers all that much.

Also, OP-1's synthesis capabilities are much deeper than it would seem from reading the manual or watching a typical review. And it has an amazing online community.

Yeah but... Way more people have phones. Just send your emergency broadcast by SMS. There's even an official way to do that.

For uses like that AM on the regular MW band (530 to 1600 KHz) is much better. FM receivers are relatively complicated compared to AM receivers, require more and more complex parts and in general are a lot harder to put together without substantial skill. Then, finally, the range of FM transmitters is limited and during war you'd want to stay in touch with 'the free world' as much as possible which quite likely is substantially over the horizon.

.....young people don't have FM radios --- those who don't own cars.

No one I know does.

My cellphone is an FM receiver if you plug in earphones to act like an antenna. It's not like the headphone jack is going anywhere...

That hard "if" really bothers me, too. My phone has the FM receiver unlocked, but the software will not allow it to be turned on unless there is something plugged into the headphone jack (which my phone is also progressive enough to still possess). I am fully aware that the reception is going to be poor without a good antenna, but it really bothers me to have that option taken away. I'm standing right next to a kilowatt transmitter. Let's give it a try and see what happens, no?

Trust the computer, the computer is your friend.

And here I am with my iPhone 7 that does not have an headphone jack.

Pixel too :(

Your iPhone doesn't have an FM receiver anyways:

https://www.theverge.com/2017/9/28/16379316/fcc-iphone-fm-ra...

> “iPhone 7 and iPhone 8 models do not have FM radio chips in them nor do they have antennas designed to support FM signals, so it is not possible to enable FM reception in these products,” an Apple spokesperson said in a statement.

I'm not really "all change is bad" kind of a guy, but I've already lost the damn dongle 2 times and had to buy a new one. I think bluetooth headphones are the future, but for now they're simply way too expensive if you're going for quality :/

My phone can play FM radio by plugging in a pair of wired headphones. And while most young people don't have cars, pretty much everyone around here has one of those.

Many Android phones contain built in FM tuners, carriers just don't currently utilize them:

https://www.cnet.com/how-to/unlock-the-secret-fm-tuner-in-yo...

Interesting. This was pre-installed on all smartphones I owned (and I expect it to), perhaps this is something carriers incentivize to disable in some countries?

It seems like that use case is being taken over by cell phones, which the government can mass-message in an emergency. Of course, that requires a lot more infrastructure that could potentially get taken out by that same emergency.

FM is just a mode of modulation. A general purpose receiving radio can have multiple modes (AM, FM, WFM, SSB, digital, etc.). I would not worry about receivers dropping support for FM.

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