Another interesting note about the FM frequencies is stations from 88 MHz to 92 MHz are the non-commercial part. That's why you'll find a lot of NPR and religious stations at that part of the dial rather than the other end.
(Looked up after many hours of road tripping through states with very few radio stations)
Your experience (listening to non-commercial stations on the left side of the dial while road-tripping) was memorably summarized by the Replacements in "Left of the Dial" --
Norway killed its FM transmission, a perfectly functioning technology. Pure one to many distribution perfected over time, deprecated.
DAB+ radio has much lower range and the signal is unstable.
To make matters maybe even worse, HAM radio operators at work inform me the DAB+ standard isn't going anywhere and that the development has mostly stopped. Maybe somehow 5G can do some marvels for the technology, time will tell.
AM had the nice property that it worked somewhat in mountainous areas, but it didn't sound very good. It had the nice property of range.
FM sounded better than AM but had to be more-or-less line-of-sight. It also had the nice property of range.
DAB+ is like an abandoned FOSS project that everyone jumped on like it was Zoom before naked dudes were jumping into online church services and online elementary school classes with zoombombing.
5G is boondoggle unrelated to radio for cellular connectivity that requires much more infrastructure since sub-mmw can't go through many materials at its higher frequencies. I swear it's a conspiracy (theory) to sell 50x more tower gear than 4G LTE. We already have gigabit 4G LTE, sub-mmw 5G just seems uneconomically undeployable at-scale.
Technologies shouldn't be adopted simply because they're new or being pushed by vendors. Heck, Apple doesn't even have any 5G phones because 5G may not survive once the major carriers wise-up.
> Technologies shouldn't be adopted simply because they're new or being pushed by vendors. Heck, Apple doesn't even have any 5G phones because 5G may not survive once the major carriers wise-up.
I’m pretty sure the next generation of Apple phones (iPhone 12?) will be 5G compatible, when the current generation came out 5G was barely deployed (still isn’t in a lot of places).
So that’s more a matter of timing than Apple not believing in the technology.
> I’m pretty sure the next generation of Apple phones (iPhone 12?) will be 5G compatible... that’s more a matter of timing
...
agree with your reasoning, not your conclusion.
I don't think there will be material 5G buildout by the end of 2020 (even before the Covid-19 crisis I didn't believe that). So unless there's an important market with significant 5G buildout (not sure anybody really has "significant" and certainly none of the important markets do) they'll continue to wait.
This is especially true as current 5G devices have larger physical size and abysmal battery life. Apple can't fix that problem on their own; part of the problem is build out and part of it will need to be solved through the experiences of the radio chip vendors and their current customers.
Compare this, say, to WiFi 6 which Apple already deploys in their 2019 iphone 11 and 2020 ipads. hat is a little ahead of the curve (chip sets are OK but there's little deployment yet). Wifi base station deployment will trickle out and until then there's no negative cost for Apple's users (i.e. no effect on battery nor size).
Apple's waiting to see if 5G implodes and is replaced by something else better or equivalent that doesn't cost the carriers nearly as much to deploy and maintain. It seems crazy to have to deploy 1-2 orders-of-magnitude more equipment just to provide coverage equivalent to gigabit 4G LTE, and having to deploy inside of buildings as well; it fails the common-sense "smell" test and I think it will be dead by 2024.
AM had the nice property that it worked somewhat in mountainous areas, but it didn't sound very good. It had the nice property of range.
AM can sound better, but it requires people to buy new radios, and the whole point of AM is that it's cheap.
I had a Sony AM Stereo Walkman, and if the station was broadcasting in AM Stereo, the sound was considerably better. Not FM quality, but not too far off to my ears.
5G isn't just millimeter wave tech that's super fast but blocked by basically everything.
On the frequencies that 4G uses, 5G is a moderate upgrade. Somewhat better speed, notably better latency.
5G will also add more wifi-adjacent frequencies, only slightly higher than existing networks use, which sounds like a perfectly good idea to me in dense areas.
I'm normally pro-digital over anything analogue, but broadcast radio is one medium, possibly the only medium, where analogue is better.
Digital compression simply doesn't cope with packet loss well enough to be practical. Even with a very weak FM signal, in emergencies you can still hear through the noise.
In rural places in the US, it's terrible for television. Several years ago, it was mandated that TV stations switch from analogue to digital.
Now instead of getting a little static and being able to understand 100% of what is said and shown over the air; it's now 10% recognizable video 90% visual blocks, and 0% audio.
Not just rural. In downtown Seattle, there's nearby stations I can't get at all. KIRO 7 (CBS affiliate) reception is unwatchably bad maybe half the time. Maybe it's the hills? I don't remember analog being this bad. I can pick up analog radio stations all the way from Vancouver.
If the digital transition hadn't happened I think over the air television might have died by now. Analog broadcast used significantly more electricity and fewer and fewer people would be interested in the low quality signal. Stations might have decided the remaining viewers weren't worth the power cost.
What's the difference in power for analog vs digital TV broadcast?? Is that mostly because ATSC broadcasts moved towards UHF, and NTSC broadcasters preferred VHF when available? Or is there some other property of ATSC broadcasts that require lower energy?
Analogue video has to have a very high SNR at the receiver, because any noise is directly visible in the picture.
But with a digital signal, as long as you can distinguish individual bits, the picture is always perfect, so you can get away with a much lower signal strength.
Digital doesn’t have to mean compressed. CD audio isn’t compressed; in fact the opposite, it’s expanded with fountain codecs. I don’t see why putting a digital signal of that approach on the air, wouldn’t result in better decoded SNR per bandwidth than analogue signalling. Emergency signals could add more error-correction per bit, to the point of even becoming non-real-time (i.e. your receiver would need to buffer the signal for a while before it could play any of it, but this would be fine, because the signal is likely repeating anyway.)
I mean, this is already how satellite (especially interplanetary satellite) communication works.
HD Radio has some of the same disadvantages as digital TV — if you don't have a strong enough signal, it drops out.
The worse part, to me, is that it takes quite a long time for the HD signal to lock in. I had a brand new rental car last month with a brand new HD radio in it. It took upwards of ten seconds for some of the HD signals to lock in.
Radio stations (AM and FM) can improve this by going all-digital, instead of the hybrid technology almost all are running right now. But doing so not only excludes hundreds of millions of older radios, it reduces the coverage area. It's simply not worth the revenue hit, since in radio coverage area is everything.
On the plus side, I had a great Sony HD tabletop radio that I loved dearly. It had an iPod dock on top and if a song came on the radio that you liked, you'd press a button and the track information would be stored in a special playlist the iPod.
Then the next time you plugged the iPod into iTunes, it would match the information from the playlist and you could buy the song you heard on the radio from iTunes. It worked really well. I wish something like that existed for satellite radio.
A while back a local station was having a problem and their analog signal was off but they were still transmitting digital. When I tuned in it was kind of funny because it was all static and then it faded into whatever music they were playing.
I've always wondered what full digital stations do, but for the reasons you've said I doubt there are any.
I always wondered why apple never integrated something like this into their iPods and iPhones. AFAIK, the Bluetooth chips in the devices were capable of FM radio reception. It always seems like a perfect chance to get radio users into the iTunes ecosphere. Heck, there may have even been an ad-revenue opportunity? (Radio ads that trigger screen ads on the device?)
Yeah, it's maddening, isn't it? I would never go back to analog cell phone systems, and I could waffle for hours why analog TV is really not as great as some might remember, but for radio transmission FM stereo radio was simple, elegant and with great quality. DAB+ is in many ways a step backwards, I think.
DAB+ was meant to deliver high-quality AAC above 128 Kbps, preferably 192 Kbps or higher, unfortunately it ended up being broadcasted using the lowest bitrate to squeeze as many stations as possible, usually at 64 Kbps, it's a total disaster...
Analog cable was superior for channel surfing. No digital buffering meant you could change channels instantly to surf back and forth like changing between browser tabs.
Earlier small-dish satellite systems sort of worked around this by showing each I-block as it came in (something like , instead of waiting for the full frame to be available. You still had to wait for enough macroblocks to show up, but audio was instant. Later receivers (last time I used one a long time ago) waited for a full frame to be available instead of showing the blocks as they are displayable.
I have been trying to look up what this I-frame-less encoding method is called, but it's impossible to find niche topics like this on Google or DDG these days (tried intra sweep, iframeless, progressive intra, without iframes, etc).
It's actually sad that DAB+ is now set in stone using AAC, while in the meantime Opus has been developed which is more or less optimal regarding aural information per bandwidth (see the spectrum diagrams).
-No, most people simply stopped listening to radio in their cars, or bought DAB adapters which rebroadcast the DAB channel you wish to listen to on an FM frequency.
A lucky few with cars old enough to have a standard DIN car stereo bracket simply popped out the FM radio and dropped in a DAB replacement.
But, essentially, radio listening in both car and home dropped off a cliff.
Edit: The Great FM Kill-Off was a double whammy as they simultaneously stopped broadcasting DAB using the MPEG2/L1 codex and switched to DAB+' HE-AAC.
This made sense, technologically - sound quality of low bitrate MPEG2 is not impressive - but the result was that most early adopters of DAB had to purchase new receivers yet again as early DAB sets did not support DAB+.
Further, leading up to the FM shutdown all the focus was on FM=>DAB, not DAB=>DAB+ - so during the switch, three of my four DAB radios went the way of the dodo bird without me even having realized it was going to happen. I wasn't very motivated to buy new receivers yet again...
I got an option to switch to DAB+ from my (previous) dealership but I just don't see the point. It's much better just to use mobile broadband and stream whatever you want using your phone + bluetooth.
My new car has DAB+ but it also has tunein and spotify built-in so that's a much better option.
FM isn't dead yet here in Norway though you can still listen to local stations via FM and it looks like the license for them will be extended to 2031.
Yes, DAB uses less bandwidth than FM, this is more or less its only advantage.
It also uses a bit less power at the transmitter, but the receivers are more complex and need more power than FM receivers (afaik), which is a bad tradeoff.
Here in the UK you get stations ending in any decimal. Other countries have different schemes. It’s a thing when you import a car from Japan for example, the FM bands are different so you have to swap the radio or buy a little band expander box to fudge it.
I once had a car radio which enforced this rule. Wouldn't tune to anything except odd decimals.
And it worked fine in my home city, every single radio station was on an odd frequency.
But I don't live in the US. One day I went on holiday to another city, and in that city and 90% of radio stations were on even frequencies. The poor radio refused to tune into them. You could set it to the neighbouring frequency and get it half tuned in, but it would never lock.
If anyone is interested in amateur radio in the US, don't let the current situation dissuade you. There is at least one VEC now offering completely remote exams - I just took both my Technician and General exams with GLAARG completely remote.
Given there is a question in the Amateur Extra exam question pool about how VECs can properly conduct a remote exam, I'm surprised this isn't more widespread.
No clue - I barely got the chance to speak with any of the VEs; I joined the call, showed them my testing environment, took the exams, then they quickly reviewed results and next steps before leaving to start the next candidate's process. They had a day full of reservations to take exams and a pretty large waitlist of people waiting to squeeze in when they had extra time.
Er, that's in the first sentence. What could be said a little more clearly is that the frequency 90.1 is actually the channel 90.0-90.2 since the convention is to tune to the center frequency. A convention of tuning to the lowest or highest frequency of the channel would be equally valid - its just not how its done.
If you tune to the lowest frequency in the channel, wouldn't that be bad because it's on the border with the channel just below it? Tuning to the center of the channel seems like the only sensible thing to do, it's not just a convention. Or am I way off here?
All I mean is that in the modern digital world, there is no difference between a channel being defined as 90.0 + 200kHz, 90.2 - 200kHz, or 90.1 +- 100kHz. "Tuning" isn't even really a thing in modern SDR receivers that can receive a huge band all at once (it is, but more as a UI convention than an analog necessity).
This is probably just splitting hairs, but I don't think it is equally valid. Compared to the channel width, the center frequency is known / required to be set much more precisely. You could wiggle around by the bandwidth by 100s of Hertz and maybe lose some fidelity, or get some interference from neighboring channels, but you can't say the same for the center frequency.
It used to be relatively common for FM radio stations to run at over 100% modulation because it would allow them to be "louder" than the competition. Obviously this is illegal because it results in "spilling over" the assigned frequency band. But it absolutely was a thing.
Only by convention though. The radio systems I use have a configurable channel width and center frequency - there are only so many legal options. Center frequency is just a convention though - a 100kHz channel being defined as being bounded by (freq + 50kHz, freq - 50kHz) is no more logically valid than (freq, freq + 100kHz) or (freq, freq - 100kHz).
What I'm saying is that the filter that shapes the bandwidth (on either Rx or Tx) is not a brick-wall filter. The channel width isn't exactly as stated, because there's a gradual roll-off.
If I misspecified the bandwidth, I can still tune into and broadcast at the right frequency. It's not just a convention, it follows how the transmitted and received signals are actually processed. I do not think it's more logical because setting the center frequency and setting the bandwidth of the baseband signal are two independent operations. Conceptually, they are orthogonal concepts. So it's logical to specify them in an orthogonal basis. Choosing another basis, as you're saying, works. But the current "convention" is more than just a convention. It's the natural choice.
If I take my FM radio and take it somewhere that uses different channel spacing, I can still tune it to the advertised frequency. That would not be the case with what your proposing.
What could be said a little more clearly is that the frequency 90.1 is actually the channel 90.0-90.2
Not strictly. The main channel is 90.1. But many FM stations have sideband channels for various audio and data services, like reading books and newspapers to the blind.
After reading the whole article, I was still wondering why they didn't just put the center of the frequencies on the even numbers. Then I realized that's not the order in which they decided what to do.
The article doesn't really answer why. It basically says that FM is channelized first and then the center frequencies are determined; while AM is assigned center frequencies first.
I've lived in the US for many decades and work in commercial radio, and this is the first I've heard of there being channel numbers for analog broadcast FM radio (as opposed to frequencies). I have seen channel numbers or designators like "Blue Dot" sneak into infrequent parlance in lieu of frequencies assigned by the FCC in other bands. But, this is increasingly uncommon, or in the latter case, based on manufacturer specific use.
Not terribly surprised though, Title 47 is crusty and full of surprises - these channel numbers are certainly defined somewhere.
Ha, it had to be somewhere. The last I recall hearing "megacycles" was in Bond movies from the 1960s. Wikipedia says this was 1960: https://en.wikipedia.org/wiki/Hertz#History
I've lived in the US for many decades and work in commercial radio, and this is the first I've heard of there being channel numbers for analog broadcast FM radio
Then the station you work for must not have any repeaters or translators.
When you hear a legal ID like "KHNH/Randoville, K226AR/Hacktown," the translator it got its call sign because it's on channel 226. All of the AM frequencies have channel numbers, too.
I worked in radio for ten years, and wasn't even on the technical side, and I knew this.
All the channel numbers are used. But in the analog days, channels were separated by market to reduce interference. One market would use 2, 4, 5 and 7 while the adjacent market would use 3, 6 and 8.
By the way, in Europe, even for analog TV the channel numbers have been relatively hidden since at least the 80s. TVs would instead be "programmed" to have sequential program numbers, which behind the scenes pointed to actual channel numbers. The channel a station was on could differ widely between regions, so the channel number was just a local implementation detail.
There is/was also usually some more or less common order of stations, e.g. in Germany you'd always put ARD on 1, ZDF on 2, the regional "third" station on 3...
For a long time in the US (maybe still?), the vast majority of the schedule was set by the local station. Being a member of one of the national networks brought access to a catalog of shows, and a few requirements about the scheduling of shows that the network really cared about. In almost every nationally-produced promo you got the phrase “check your local listings” in addition to the advertised time because the local station might air the show sometime other than when the network recommended.
It has to do with how to hit a consumer price point with a receiver for a complex modulation scheme using only a couple dozen active devices and cheap-to-manufacture filters.
Original NTSC monochrome television is a 6 MHz wide channel, the video carrier is 1.25 MHz up from the bottom, and at the transmitter a filter lops off most of the lower sideband.
For receivers, the problem is the IF filter. Filters with steep skirts are hard to build and align, and are expensive. So... channel allocation was done with the assumption that most consumers would have receiving sets with poor adjacent-channel rejection because of using cheap filters. This was solved by channel allocation -- do not let two stations with overlapping grade-A signal contours be on adjacent channels. Problem solved.
In the very early days in the US, channel 1 was 48-54 MHz. They found out that the percentage bandwidth was too wide to be able to build a practical transmitting antenna for channel 1. The SWR was too high at the band edges, and high SWR on analog TV means the transmission line generates ghost pictures. So channel 1 was dropped. Now hams have the 6 meter 50-54 MHz band, and cheap license-free R/C toys and walkie-talkies have 48-50 MHz.
Channel 2 is 54-60, 3: 60-66, 4: 66-72 and then a gap: 72-74 is radio control, then channel 5 is 74-80, and so forth, and if I recall correctly there is a big gap between channels 7 and 8 so even though they are sequential numbers they are not frequency-adjacent channels. (7 and below being the so-called "low VHF" and 8-13 the "high VHF" TV channels.)
The 2 MHz gap between channels 4 and 5 was also used to advantage, as it was enough to eliminate the adjacent-channel interference problem on reception. I recall when I lived in Minneapolis, that channels 2, 4, and 5 were all allocated in the metro area. Channel 3 was Mankato, far enough away that if you lived between Minneapolis and Mankato you could receive all of those stations without interference problems, being in the grade-B signal contour of both.
And..... this entire post contains obsolete information of historical interest only, and even at that, of interest to very few. Now... excuse me because I have to readjust the spark gap on my 200 meter transmitter...
The US Department of Commerce publishes a wall chart showing how the difference parts of the spectrum are allocated to different services. Notice how bands for "Broadcasting (Television)" are broken up and interspersed with those for other services such as aeronautical navigation and FM radio, despite the TV channels having consecutive numbers:
I suppose "frequency modulation" (FM) would mean that you'd need to separate frequencies so each station can "modulate" without running into the neighbors. That's quite a satisfying thing to learn.
Well, that is an intuitive way of looking at things, but ANY signal carrying information has non-zero bandwidth. Even an AM (amplitude modulation) signal occupies a band of frequencies.
Something I've always wondered is where the channel "names" come from. The ones that are usually 4-6 characters, seemingly random, often starting with K or W for some reason. Like KVUE or W2XMN or KLTY.
Thats just a callsign, all callsigns in the US start with K, W, AAA-ALZ or N, commercial broadcast services use K and W exclusively. Commercial Broadcast stations are generally three or four letters, with a suffix like -FM, -TV, -DT, -LP, or -FM1, its even possible to have multiple suffixes stacked KWWW-LP-FM1.
Translators can have even more characters and are a combination of numbers and letters.
Experimental stations are generally W or K a region digit, and three letters starting with X, these are issued out of the pool of callsigns used for amateur radio stations.
Buiness band and GMRS licenses use the same format, generally three or three letters starting with K or W, and three or four numbers.
All commercial radio and television stations in the US have call signs starting with K or W. The division is geographic -- west coast stations use K; east coast stations use W. (The dividing line is, roughly speaking, drawn at the Mississippi River.)
It took me a while to realize there was any geographic significance. I live in a metro area split by the Mississippi, so we have a roughly 50/50 ratio of K and W stations.
I think the FM callsigns for the same station were different (four characters rather than three), however could be related, but the callsigns were eventually dropped or incorporated into the station name as it stopped being a thing broadcast stations needed to announce (or maybe even have.) For example, as the station that had that antenna above started FM, it had a callsign but now it's just left in the name: https://en.wikipedia.org/wiki/ZM_Wellington
I think they would be less prominent in the USA if stations weren't required to identify. We have a station in Phoenix that identifies as KISS FM, a brand that originated with KIIS-FM out of LA. But every once in a while they will say their real callsign KZZP.
Same on TV, when I was a kid our PBS stations always went by KAET, later on they went by the channel number Eight. Now that people might not even be watching on a channel (streaming) they just go by Arizona PBS, but every once in a while they show their station callsign and the call sign of all the translators (stations that transmit identical signal in other parts of the state)
These seem to be commonly used in the USA - are they used elsewhere?
They're used everywhere, but not every country requires them to be spoken aloud. They can be transmitted or recorded in other methods that are not audible to the listener.
Japan, for example, uses the American method. You can hear it if you stream JODW/Tokyo.
Personally haven't seen them anywhere else at least. While the stations might or might not have call signs on paper, they are certainly not used in any way a listener would notice. (Of course I can only speak for the countries I've been to.)
(Looked up after many hours of road tripping through states with very few radio stations)
https://en.wikipedia.org/wiki/Non-commercial_educational_sta...