8 ms·
The problem with digital radio is that it's all or nothing. Analogue degrades gracefully, if you need to listen to the news in an emergency, it doesn't matter
by RobotToaster 2y ago
The problem with digital radio is that it's all or nothing.
Analogue degrades gracefully, if you need to listen to the news in an emergency, it doesn't matter if it sounds fuzzy.
- kachapopopow 2y agoFM radio will still exist afaik. Nobody in my country used AM for a decade now.
- LeoPanthera 2y agoThe useful range of FM is much shorter. The reason why AM transmitters remain so useful in geographically large countries like the USA is that you need far fewer transmitters to reach everyone.
- bigfishrunning 2y agoThat has more to do with the frequency band then the modulation scheme. I wonder if long range FM in the ~1000khz broadcast band would make sense in the future. It would get the range of AM broadcast radio with the quality of FM (but it may require too much bandwidth to be practical)
- wakawaka28 2y agoI'm no expert but I think lowering the frequency far below the current standard was not feasible due to the frequencies and ranges being transmitted.
- LeoPanthera 2y agoYou're not wrong, but that's useless nitpicking. We're not going to suddenly introduce a brand new radio standard that no-one has a radio for. There are literally millions of AM radios out there in the US, at the already agreed frequency range. For emergency broadcast uses, the increased quality of FM is meaningless.
- nahumba 2y agoThe advantage of am over fm is the simplicity of the electronic circuit. In am its very easy to create a receiver to listen to broadcast. While an fm radio is too complicated for amature electronic. So i dont belive am will ever be dropped for emergency radio
- Tor3 2y agoFM radios aren't complicated at all. And FM transmitters, in particular, are extremely simple. When I was a student we had a tiny one we made in an afternoon (this was decades ago), we connected it to our 8-hour reel tape deck and had our own music station in the car radio when we drove around in the area. The advantage of AM is, as was mentioned already, the lower frequency used by AM which means much better coverage. FM 87MHz-108MHz is almost just line of sight.
- kmbfjr 2y agoNo much to a coil, antenna and a germanium diode.
- candiddevmike 2y agoThe geranium diode is doing most of the heavy lifting. Good luck building that from scratch.
- fmj 2y agohttps://rimstar.org/science_electronics_projects/razor_blade_diode_for_crystal_foxhole_radio.htm https://rimstar.org/science_electronics_projects/razor_blade...
- bsder 2y agoGalena cat whiskers were quite common: https://en.wikipedia.org/wiki/Crystal_detector https://en.wikipedia.org/wiki/Crystal_detector
- 2y ago
- btbuildem 2y agoIf I recall correctly, FM needs the higher frequency carrier band to actually M the F effectively. You'd also need much longer antennas for this. The amplitude-modulated signal also needs far less bandwidth than a frequency-modulated one, so it would not "fit" at ~1000kHz because there are other reserved bands nearby.
- asdefghyk 2y agoThe problem is the amount of Bandwidth taken at the lower frequency.
- kstrauser 2y agoThe bandwidth is the dealbreaker. Commercial FM radio has a necessary bandwidth of 270KHz. That’s not a lot when your carrier frequency is around 100,000KHz. It’s a whole lot when your carrier is around 1000KHz. For comparison, commercial AM mono bandwidth is 10KHz. SSB AM ham radios use 2.4KHz.
- anticensor 2y agoCommercial AM has a 5kHz bandwidth (4.5kHz in Europe), commercial FM 50kHz (29kHz if mono). The remainder of the channel is guardband.
- kstrauser 2y agoSource for 270: https://en.wikipedia.org/wiki/FM_broadcasting https://en.wikipedia.org/wiki/FM_broadcasting. Search there for “necessary bandwidth”. For AM, that’s 5KHz+-, or 10 total.
- ssl-3 2y agoThe broadcast AM band is 1.6MHz wide. Broadcast FM stations are spaced at 200KHz intervals, of which about 150KHz is used for modulation and the remaining ~50KHz is used for guard bands. Thus, current standards, the entirety of the broadcast AM spectrum can support no more than 8 concurrent FM broadcasts in a region. And maybe that "works," but it certainly doesn't leave much room for competing markets. When multiple stations with wide propagation all use a singular frequency, they have to be geographically spaced quite far apart: The hypothetical Toronto station centered at 1330KHz station would step on the Detroit station at the same frequency, which would step on the Chicago and Cincinnati stations. And, sure: One could give one channel to each market to reduce this co-channel interference, but then there's not enough density for any meaningful competition. (And our band of capitalism requires competition in order to even begin to work.)
- sidewndr46 2y agoLong range FM does not work because of the multipath effect. Even on 29.6 MHz it's quite pronounced.
- wakawaka28 2y agoFM radio is radically limited in range. You can listen to AM or shortwave across a whole continent, or even across oceans. With FM you're very lucky to hear something over a hundred miles away. AM radio is most popular for news and talk shows, and emergency broadcasts.
- RHSeeger 2y agoWhen I was living in "upstate" NY (the Poughkeepsie area, which isn't upstate, but that's what it's called), I would regularly listen to AM stations out of NYC (close to 100 miles away from the broadcaster); using just the standard receiver in my car.
- musictubes 2y agoGrowing up in the 80s we would regularly listen to WKBW out of Buffalo in Virginia. AM has amazing range.
- netdevnet 2y agoFM has less issues with interference (which is critical if you want to deliver a message) and quality (which you will care about for music)
- wakawaka28 2y agoFM definitely wins for audio quality. But if you are facing a major national disaster where Internet may be down in various places, you need to have AM. The quality is plenty good enough in most cases. Even in the worst cases, it rarely performs worse than a traditional phone call. Really, the quality issues become apparent mostly because you can easily get partial reception on stations that are extremely far away, leading you to think that the technology is inherently bad. It's not a binary success outcome like digital TV signals. When AM radio was more popular I would often listen to AM stations, with some of them being pretty far away. Back in the days before the Internet, radio was THE way to get informed.
- ajsnigrutin 2y agoIn europe, some are actively trying to kill FM radio and switch to DAB... so it's coming, first the european cars, then the others too.
- kachapopopow 2y agoAll new cars have (at minimum) 2G connectivity already as well.
- dylan604 2y agoThen whatever decision Congress makes will have no affect on you
- kachapopopow 2y agoIt can be used as an example on why AM should be killed.
- GJim 2y ago> FM radio will still exist afaik. Nobody in my country used AM for a decade now. Some fool has downvoted you for making a factual statement. It is indeed the case that long and medium wave (AM radio) broadcasts have ceased in Ireland and several other countries; FM and DAB only here. Whether this was prudent thing to do for reasons of emergency broadcasting is a different question.
- mplewis 2y agoDigital radio remains working at much worse SNR than intelligible fuzzy analog.
- greesil 2y agoFor comparable BER. I wonder what SNR is needed for speech to be intelligible? To be fair, if someone made a voice encoding only with that had a lot of error correction bits, it would probably work at much longer distances. Some of the codecs are 2 kilobits per second for human voice? That's got to have a way better margin for the same channel bandwidth than analog decoded by the human brain. This way we get the digital advantage and lossy compression.
- moandcompany 2y agoYou may find the MELP Vocoder and history interesting: https://melp.org/ https://melp.org/ (MIL-STD-3005) MELP targets 2.4kbps, and there are later examples for even lower bitrates (e.g. 1.2kbps, 600bps) One thing to keep in mind is that a lot of these codecs or technologies are designed to operate at very low bit rates because the signal carrier is required to be capable of operation in "contested environments" where jamming and/or other environmental effects are present (and throughput potential is the tradeoff for assurance).
- hulitu 2y agoCitation needed.
- cogman10 2y agohttps://opus-codec.org/demo/opus-1.5/ https://opus-codec.org/demo/opus-1.5/ Especially for speech, there are aggressive and impressive algorithms that can turn a trickle of bits into understandable voice.
- sitkack 2y agoThere isn't an FEC format that uses Opus over a radio signal. We could make one, but analog AM is the best we have for extremely wide area robust voice broadcast.
- Aloha 2y agoRight, but digital radio is a small portion of the US market, and what IBOC stuff that did happen, much of it has been turned off. So I dont really understand what this comment has to do with the article at hand here?
- Gigachad 2y agoAnalogue doesn’t degrade gracefully. Every time you drive under a power line it becomes completely unintelligible. Meanwhile digital radio can use error correction to maintain perfect quality under heavy interference.
- winkelmann 2y agoThis sounds like a signal strength (or maybe frequency?) issue more than an advantage of digital. I sometimes hear people report the opposite of your experience, but many factors play into that. Your point about error correction and perfect quality is noteworthy. Yes, if there is some data loss, error correction can maintain perfect quality, but once that fails, it fails badly. And it's not even all-or-nothing: The radio may, due to an arbitrary firmware configuration, refuse to tune into a stream that is still partially intelligible if it deems the signal integrity or strength to be insufficient. Even very damaged digital streams can be somewhat useful, if you can deal with lovely artifacts like piercing chirping noises when the decoder doesn't know what do to with garbled data.
- mcmoor 2y agoYeah when my national tv is transitioning from analog to digital, in some conditions where the analog channels quality degrade, the digital channel fail completely.
- Gigachad 2y agoDigital tv can degrade gracefully. It just looks different. Instead of fuzz it looks like missed iframes which create blocky artifacting on movement or when switching cameras.
- stroupwaffle 2y agoI’ve always wanted to drive in circles under power lines listening to the Jethro Tull Christmas special!
- okanat 2y agoTo be able to decode under heavy interference you need heavy error correction in the digital hardware and in the standard. Nobody designs space-grade consumer radios. You are basically limited with the bits you have and the recovery you have, no more. A really bad digital signal is unintelligible by definition. It is a sharp cutoff when you reach the limit. However an analog signal is ehmm .... an analog of the original. It is continuous. So the error is also analog and you're only limited by the average case. The signal degradation is also analog, there is no sharp cutoff. So as long as human brain can extract the information from the noise, analog continues to work.