4 ms·

Long wave radio fans mourn fading frequencies (2023)

79 points by austinallegro 2y ago

idunnoman1222 2y ago
Why are they calling this long wave instead of just AM radio?
- drmpeg 2y ago
  It's at a lower frequency, 148.5 to 283.5 kHz.
- HL33tibCe7 2y ago
  Long wave != AM: long wave implies AM, but not vice versa (AM can be - and usually is - used on medium/short frequencies)
  - lxgr 2y ago
    > long wave implies AM, It doesn't: There's a lot of non-AM/non-voice stuff on longwave, most notably various digital time beacons (WWVB in the US, DCF77 in Western Europe etc.)
- ianburrell 2y ago
  Cause longwave (148-283 kHz) is only part of AM radio. Most of it is in medium wave (525-1705 kHz) and some shortwave (2.3-26 MHz).
- Todd 2y ago
  LF, MF, and so on are bands, or frequency ranges. AM is a modulation technique. It, like FM and others, can be used on any band (although regulations can limit this).
- wpm 2y ago
  Does my wavelength imply my modulation technique?
  - jimnotgym 2y ago
    Well, yes and no. Inside specific areas of all bands there is a convention to use specific modulation. On the Amateur bands, whilst you are free to use whatever you like, there are conventions that CW, digital, SSTV, SSB and FM are generally grouped into sub- bands. It helps people find each other, so is pretty useful. If your receiver is set to FM you might not notice a CW signal. On other commercial bands the mode is enforced.
- musicale 2y ago
  I think this was an honest question? I have noticed that regular medium-wave AM seems to have decent propagation (though maybe not many thousands of miles) and also improves at night.
- mikewarot 2y ago
  Because commercial AM radio is 540-1710 Khz in the USA. Also note that aircraft use Amplitude Modulation even though they are in the VHF radio band.
- Johnythree 2y ago
  AM is a type of modulation which is widely used by many different services (eg Shortwave broadcasting, CB radio, Aircraft VHF, etc). However "Longwave and Mediumwave Broadcast" unambiguously refers to that service.
- soneil 2y ago
  The US often just says 'AM radio' to refer to the MW band, because they don't have commercial broadcasting on the LW band, so there's no need to disambiguate. In the UK we usually specify LW or MW because both bands are in use for 'AM radio' (for now ..). Same way we just say FM for the 88-108 broadcast band. Were there two FM broadcast bands, we'd need to give them different names.
  - idunnoman1222 2y ago
    In the UK, you have a button on your radio that switches between AM FM and a third option? Or just those two?
lxgr 2y ago
As far as I know, the UK's nuclear submarine fleet used (or still uses?) the presence of a Radio 4 broadcast signal as evidence for the continued existence of the UK. Hopefully they have other means at this point!
- throw0101d 2y ago
  From 2020: > During the time following a perceived attack, a series of progressive checks are made by submarine crews leading up to the captain opening the letter. These include trying to listen for radio transmissions from various levels of Royal Navy and Ministry of Defense command using multiple methods, and most famous of all, listening for new radio broadcasts by BBC Radio channel four, and specifically new episodes of BBC Today. […] * https://www.twz.com/7300/letters-of-last-resort-are-post-apocalyptic-orders-for-uk-vanguard-sub-crews https://www.twz.com/7300/letters-of-last-resort-are-post-apo... Also: * https://en.wikipedia.org/wiki/Letters_of_last_resort https://en.wikipedia.org/wiki/Letters_of_last_resort
- hilbert42 2y ago
  "…the UK's nuclear submarine fleet used (or still uses?) the presence of a Radio 4 broadcast signal" I'm not privy to the accuracy of that but it makes sense given the low frequency. In my earlier post to this story, that comes under the umbrella of what I said about that there were strategic reasons for not shutting down the LW Service and governments having nanny goats for advisors. As well as tbese low frequencies being better to communicate with submarines—although frequencies ten times lower (~18kHz) are much better—they travel long distances and can be very reliable over their given service areas (the ionosphere being more predictable at these low frequencies). Other reasons are that LW would provide more reliable communications during emergencies such as a mass communication outage with say the internet and other comms services being out. This could happen during nuclear war with EMP destroying much of the electronic infrastructure, similarly a repeat of the 1859 Carrington Event would deviate most existing communications infrastructure. It's dead easy to radiation-harden a LF transmitter if it used only valves (it's halfway there now as its RF output stage already uses valves).
- soneil 2y ago
  They always had other methods. Droitwich is more akin to a troubleshooting step - if Inskip is quiet but Droitwich is loud, there's a problem with Inskip. If every site falls quiet at the same time .. well on to the next step. It's a bit like losing communication with one host, and pinging another to see if it's you or them - the 'other' isn't loadbearing.
bilegeek 2y ago
I sincerely hope that if the remaining stations shut down, the band will become an amateur band. Existing 2200m and 630m are narrow, so allocating this entire range is something of a pipe dream, but it would be the best outcome. (Not sure how 1750m LowFER would be handled; maybe just keep it on as an unlicensed exception?)
- cft 2y ago
  I think LW transmission antennas are too large to be built bu amateurs
  - bilegeek 2y ago
    Full verticals, dipoles, Yagis or logs, yes. Marconi T or L antennas with capacitance hats and loading coils are well within amateur practice on 630m[1] and 2200m, and common from 40m/7MHz on down. Not very efficient still; an ERP of 1W, as demanded by the 2200m band, can still take a lot of power on a less-than-ideal antenna. Similar story for 630m. (160m and up is usually not so bad, just that even a good Marconi on longwave is still too big for most people.) But the current LowFER[3] regs limit the transmitter to 1W final stage input power, and a COMBINED feedline and antenna length of 15m. At least allowing amateurs to operate more here would allow more than just extremely low SNR modes like WSPR to be used at any real distance. [1]https://www.hamsignal.com/blog/dog-days-and-the-marconi-t-antenna https://www.hamsignal.com/blog/dog-days-and-the-marconi-t-an... and https://vk6ysf.com/t_antenna_arrangment.htm https://vk6ysf.com/t_antenna_arrangment.htm [2]https://en.wikipedia.org/wiki/2200-meter_band#International_frequency_allocation https://en.wikipedia.org/wiki/2200-meter_band#International_... [3]https://en.wikipedia.org/wiki/LowFER https://en.wikipedia.org/wiki/LowFER
    - 8bitsrule 2y ago
      Don't see many longwave radio antennas. Here's one in Hellissandur, Iceland. 300kW output power on 189kHz : https://imgur.com/gallery/ruv-189-khz-kVght0A https://imgur.com/gallery/ruv-189-khz-kVght0A
- hilbert42 2y ago
flyinghamster 2y ago
In the US, I don't think there was any commercial LW broadcasting (but I could easily be wrong). US-market radios rarely had SW bands and almost never had LW unless they were general coverage receivers. For the most part, the few times I looked through the band it was largely navigation beacons. I was rather surprised to see an LW band on a regular clock-radio when I visited the UK, though that was 25 years ago.
- LeoPanthera 2y ago
  There has been no commercial broadcast radio on the longwave band in the US, that's correct. That's why radios featuring that band are rarer here, and usually confined only to enthusiast radios. The WWVB time signal is technically inside the longwave band, at 60kHz.
- CalChris 2y ago
  Not broadcast, but there was marine longwave for point to point telegraphy. KPH would send messages to ships at sea at about 500kHz and it did broadcast news, weather albeit in Morse. It still exists as a museum and broadcasts occasionally. https://www.nps.gov/pore/planyourvisit/kph_treetunnel.htm https://www.nps.gov/pore/planyourvisit/kph_treetunnel.htm KFS still has a transmitter antenna farm in Palo Alto off 101 with a receiver antenna farm in Half Moon Bay. https://www.radiomarine.org/historic-coast-stations/kfs-san-francisco https://www.radiomarine.org/historic-coast-stations/kfs-san-... https://coastview.org/2024/01/28/kfs-high-frequency-receiver-half-moon-bay/ https://coastview.org/2024/01/28/kfs-high-frequency-receiver...
woliveirajr 2y ago
My first contact with English was listening to the Radio Canada International. Then I knew that I needed to learn it to receive news that only would be in newspapers 2 or 3 days later. Now there are none stations that I can listen at night, and I miss it
- amatecha 2y ago
  Yeah, I've scanned the radio bands at night hoping to pick up something neat like this, but never really had any luck. Sometimes stuff in Spanish or Chinese, not much else :\
- jhoechtl 2y ago
  I am sure you mix long wave reception with shortwave reception, some different bands, wave lengths and propagation characteristics.
hilbert42 2y ago
"Plus, an article in The Guardian in 2011 claimed that only a small number of spare valves were still available for the transmitter." What a pathetic argument! When you read crap like this you know you're being told sop—an attempt to bamboozle the public with technicalities that don't really exist. Any commonly available high powered RF tetrode from an FM or TV station would do the job albeit with some (mostly mechanical) modifications to the transmitters. Also, it's a common practice to refurbish high power transmitting valves, there are companies that specialize in doing it. I say that as someone who has been involved with high power broadcasting transmitters, in fact I was involved in building several FM broadcast transmitters from the ground up. At only 198kHz—which is somewhere between one 1/500th and 1/1500th its normal operating frequency—any high power VHF transmitting tetrode would be just loafing along. No doubt the way commerce works getting a one-off specialist job to do the conversion would be expensive (I wish I could do it, I'd quote half the price and still make a handsome profit). If the BBC is so strapped for cash perhaps it could ask the Amateur Radio fraternity to mod the TXes for free as a public service. Then after the mods the service could recommence on half power to save costs. Also, there are good strategic reasons why this transmitting infrastructure should be kept operational on these low longwave frequencies which I haven't got time to address here. Suffice to say, I think this proposed closure is more a hatchet job by accountants than from any long-term strategic thinking by governments. Damn shame governments only seem to listen to nanny goat advisors these days.
- bilegeek 2y ago
  I agree it's 99% ridiculous, but to play the devil's advocate: modifications could require re-certifying the transmitter due to regulations, which might make them not financially worth it after the remaining correct tubes die. Especially since regulations governing something so boutique and relatively obscure haven't probably been updated much to make stuff like this easier. (I confess high ignorance to UK law.)
  - hilbert42 2y ago
    I've been through the certifying process for broadcast transmitters from scratch, albeit in Australia. I can tell you it's damn easy to overwhelm the petty certifying bureaucrats, especially so when you can prove your engineering mods give better performance specs (less harmonic interference, etc.) than beforehand. In fact, our bespoke broadcast TXs gave better performance than any commonly-available commercial equipment. Bureaucrats want a quite life, and when threatened with their actual names and positions being published in the press for being obstructive over nothing then they'll cave in. Remember, troublemakers in the public sector aren't usually rewarded with promotions. :-)
veggieWHITES 2y ago
Numbers stations aren't going anywhere soon. https://en.wikipedia.org/wiki/Numbers_station https://en.wikipedia.org/wiki/Numbers_station
dboreham 2y ago
Recently drove past both the big LW antennas (Droitwitch and Hellissandur -- not on the same day obviously). Family members in car totally unimpressed by my excitement..
- macartain 2y ago
  username checks out. (sorry, couldn't resist)
mikewarot 2y ago
You can get a tiny bit of that feeling back through Radio Garden[1]. It was through this that I discovered the now defunct Wee Scone Variety Show[2] on a community radio station in Midlothian, Scotland. Unfortunately, the station seems to be missing now from Radio Garden. [1] https://radio.garden/ https://radio.garden/ [2] https://blackdiamondfm.com/programmes/wee-scone-variety-show https://blackdiamondfm.com/programmes/wee-scone-variety-show

79 points by austinallegro 2y ago

idunnoman1222 2y ago

Why are they calling this long wave instead of just AM radio?

drmpeg 2y ago
It's at a lower frequency, 148.5 to 283.5 kHz.
HL33tibCe7 2y ago
Long wave != AM: long wave implies AM, but not vice versa (AM can be - and usually is - used on medium/short frequencies)
- lxgr 2y ago
  > long wave implies AM, It doesn't: There's a lot of non-AM/non-voice stuff on longwave, most notably various digital time beacons (WWVB in the US, DCF77 in Western Europe etc.)
ianburrell 2y ago
Cause longwave (148-283 kHz) is only part of AM radio. Most of it is in medium wave (525-1705 kHz) and some shortwave (2.3-26 MHz).
Todd 2y ago
LF, MF, and so on are bands, or frequency ranges. AM is a modulation technique. It, like FM and others, can be used on any band (although regulations can limit this).
wpm 2y ago
Does my wavelength imply my modulation technique?
- jimnotgym 2y ago
  Well, yes and no. Inside specific areas of all bands there is a convention to use specific modulation. On the Amateur bands, whilst you are free to use whatever you like, there are conventions that CW, digital, SSTV, SSB and FM are generally grouped into sub- bands. It helps people find each other, so is pretty useful. If your receiver is set to FM you might not notice a CW signal. On other commercial bands the mode is enforced.
musicale 2y ago
I think this was an honest question? I have noticed that regular medium-wave AM seems to have decent propagation (though maybe not many thousands of miles) and also improves at night.
mikewarot 2y ago
Because commercial AM radio is 540-1710 Khz in the USA. Also note that aircraft use Amplitude Modulation even though they are in the VHF radio band.
Johnythree 2y ago
AM is a type of modulation which is widely used by many different services (eg Shortwave broadcasting, CB radio, Aircraft VHF, etc). However "Longwave and Mediumwave Broadcast" unambiguously refers to that service.
soneil 2y ago
The US often just says 'AM radio' to refer to the MW band, because they don't have commercial broadcasting on the LW band, so there's no need to disambiguate. In the UK we usually specify LW or MW because both bands are in use for 'AM radio' (for now ..). Same way we just say FM for the 88-108 broadcast band. Were there two FM broadcast bands, we'd need to give them different names.
- idunnoman1222 2y ago
  In the UK, you have a button on your radio that switches between AM FM and a third option? Or just those two?

lxgr 2y ago

As far as I know, the UK's nuclear submarine fleet used (or still uses?) the presence of a Radio 4 broadcast signal as evidence for the continued existence of the UK. Hopefully they have other means at this point!

throw0101d 2y ago
From 2020: > During the time following a perceived attack, a series of progressive checks are made by submarine crews leading up to the captain opening the letter. These include trying to listen for radio transmissions from various levels of Royal Navy and Ministry of Defense command using multiple methods, and most famous of all, listening for new radio broadcasts by BBC Radio channel four, and specifically new episodes of BBC Today. […] * https://www.twz.com/7300/letters-of-last-resort-are-post-apocalyptic-orders-for-uk-vanguard-sub-crews https://www.twz.com/7300/letters-of-last-resort-are-post-apo... Also: * https://en.wikipedia.org/wiki/Letters_of_last_resort https://en.wikipedia.org/wiki/Letters_of_last_resort
hilbert42 2y ago
"…the UK's nuclear submarine fleet used (or still uses?) the presence of a Radio 4 broadcast signal" I'm not privy to the accuracy of that but it makes sense given the low frequency. In my earlier post to this story, that comes under the umbrella of what I said about that there were strategic reasons for not shutting down the LW Service and governments having nanny goats for advisors. As well as tbese low frequencies being better to communicate with submarines—although frequencies ten times lower (~18kHz) are much better—they travel long distances and can be very reliable over their given service areas (the ionosphere being more predictable at these low frequencies). Other reasons are that LW would provide more reliable communications during emergencies such as a mass communication outage with say the internet and other comms services being out. This could happen during nuclear war with EMP destroying much of the electronic infrastructure, similarly a repeat of the 1859 Carrington Event would deviate most existing communications infrastructure. It's dead easy to radiation-harden a LF transmitter if it used only valves (it's halfway there now as its RF output stage already uses valves).
soneil 2y ago
They always had other methods. Droitwich is more akin to a troubleshooting step - if Inskip is quiet but Droitwich is loud, there's a problem with Inskip. If every site falls quiet at the same time .. well on to the next step. It's a bit like losing communication with one host, and pinging another to see if it's you or them - the 'other' isn't loadbearing.

bilegeek 2y ago

I sincerely hope that if the remaining stations shut down, the band will become an amateur band. Existing 2200m and 630m are narrow, so allocating this entire range is something of a pipe dream, but it would be the best outcome. (Not sure how 1750m LowFER would be handled; maybe just keep it on as an unlicensed exception?)

cft 2y ago
I think LW transmission antennas are too large to be built bu amateurs
- bilegeek 2y ago
  Full verticals, dipoles, Yagis or logs, yes. Marconi T or L antennas with capacitance hats and loading coils are well within amateur practice on 630m[1] and 2200m, and common from 40m/7MHz on down. Not very efficient still; an ERP of 1W, as demanded by the 2200m band, can still take a lot of power on a less-than-ideal antenna. Similar story for 630m. (160m and up is usually not so bad, just that even a good Marconi on longwave is still too big for most people.) But the current LowFER[3] regs limit the transmitter to 1W final stage input power, and a COMBINED feedline and antenna length of 15m. At least allowing amateurs to operate more here would allow more than just extremely low SNR modes like WSPR to be used at any real distance. [1]https://www.hamsignal.com/blog/dog-days-and-the-marconi-t-antenna https://www.hamsignal.com/blog/dog-days-and-the-marconi-t-an... and https://vk6ysf.com/t_antenna_arrangment.htm https://vk6ysf.com/t_antenna_arrangment.htm [2]https://en.wikipedia.org/wiki/2200-meter_band#International_frequency_allocation https://en.wikipedia.org/wiki/2200-meter_band#International_... [3]https://en.wikipedia.org/wiki/LowFER https://en.wikipedia.org/wiki/LowFER
  - 8bitsrule 2y ago
    Don't see many longwave radio antennas. Here's one in Hellissandur, Iceland. 300kW output power on 189kHz : https://imgur.com/gallery/ruv-189-khz-kVght0A https://imgur.com/gallery/ruv-189-khz-kVght0A
hilbert42 2y ago

flyinghamster 2y ago

In the US, I don't think there was any commercial LW broadcasting (but I could easily be wrong). US-market radios rarely had SW bands and almost never had LW unless they were general coverage receivers. For the most part, the few times I looked through the band it was largely navigation beacons. I was rather surprised to see an LW band on a regular clock-radio when I visited the UK, though that was 25 years ago.

LeoPanthera 2y ago
There has been no commercial broadcast radio on the longwave band in the US, that's correct. That's why radios featuring that band are rarer here, and usually confined only to enthusiast radios. The WWVB time signal is technically inside the longwave band, at 60kHz.
CalChris 2y ago
Not broadcast, but there was marine longwave for point to point telegraphy. KPH would send messages to ships at sea at about 500kHz and it did broadcast news, weather albeit in Morse. It still exists as a museum and broadcasts occasionally. https://www.nps.gov/pore/planyourvisit/kph_treetunnel.htm https://www.nps.gov/pore/planyourvisit/kph_treetunnel.htm KFS still has a transmitter antenna farm in Palo Alto off 101 with a receiver antenna farm in Half Moon Bay. https://www.radiomarine.org/historic-coast-stations/kfs-san-francisco https://www.radiomarine.org/historic-coast-stations/kfs-san-... https://coastview.org/2024/01/28/kfs-high-frequency-receiver-half-moon-bay/ https://coastview.org/2024/01/28/kfs-high-frequency-receiver...

woliveirajr 2y ago

My first contact with English was listening to the Radio Canada International. Then I knew that I needed to learn it to receive news that only would be in newspapers 2 or 3 days later. Now there are none stations that I can listen at night, and I miss it

amatecha 2y ago
Yeah, I've scanned the radio bands at night hoping to pick up something neat like this, but never really had any luck. Sometimes stuff in Spanish or Chinese, not much else :\
jhoechtl 2y ago
I am sure you mix long wave reception with shortwave reception, some different bands, wave lengths and propagation characteristics.

hilbert42 2y ago

"Plus, an article in The Guardian in 2011 claimed that only a small number of spare valves were still available for the transmitter." What a pathetic argument! When you read crap like this you know you're being told sop—an attempt to bamboozle the public with technicalities that don't really exist. Any commonly available high powered RF tetrode from an FM or TV station would do the job albeit with some (mostly mechanical) modifications to the transmitters. Also, it's a common practice to refurbish high power transmitting valves, there are companies that specialize in doing it. I say that as someone who has been involved with high power broadcasting transmitters, in fact I was involved in building several FM broadcast transmitters from the ground up. At only 198kHz—which is somewhere between one 1/500th and 1/1500th its normal operating frequency—any high power VHF transmitting tetrode would be just loafing along. No doubt the way commerce works getting a one-off specialist job to do the conversion would be expensive (I wish I could do it, I'd quote half the price and still make a handsome profit). If the BBC is so strapped for cash perhaps it could ask the Amateur Radio fraternity to mod the TXes for free as a public service. Then after the mods the service could recommence on half power to save costs. Also, there are good strategic reasons why this transmitting infrastructure should be kept operational on these low longwave frequencies which I haven't got time to address here. Suffice to say, I think this proposed closure is more a hatchet job by accountants than from any long-term strategic thinking by governments. Damn shame governments only seem to listen to nanny goat advisors these days.

bilegeek 2y ago
I agree it's 99% ridiculous, but to play the devil's advocate: modifications could require re-certifying the transmitter due to regulations, which might make them not financially worth it after the remaining correct tubes die. Especially since regulations governing something so boutique and relatively obscure haven't probably been updated much to make stuff like this easier. (I confess high ignorance to UK law.)
- hilbert42 2y ago
  I've been through the certifying process for broadcast transmitters from scratch, albeit in Australia. I can tell you it's damn easy to overwhelm the petty certifying bureaucrats, especially so when you can prove your engineering mods give better performance specs (less harmonic interference, etc.) than beforehand. In fact, our bespoke broadcast TXs gave better performance than any commonly-available commercial equipment. Bureaucrats want a quite life, and when threatened with their actual names and positions being published in the press for being obstructive over nothing then they'll cave in. Remember, troublemakers in the public sector aren't usually rewarded with promotions. :-)

veggieWHITES 2y ago

Numbers stations aren't going anywhere soon. https://en.wikipedia.org/wiki/Numbers_station https://en.wikipedia.org/wiki/Numbers_station

dboreham 2y ago

Recently drove past both the big LW antennas (Droitwitch and Hellissandur -- not on the same day obviously). Family members in car totally unimpressed by my excitement..

macartain 2y ago
username checks out. (sorry, couldn't resist)

mikewarot 2y ago

You can get a tiny bit of that feeling back through Radio Garden[1]. It was through this that I discovered the now defunct Wee Scone Variety Show[2] on a community radio station in Midlothian, Scotland. Unfortunately, the station seems to be missing now from Radio Garden. [1] https://radio.garden/ https://radio.garden/ [2] https://blackdiamondfm.com/programmes/wee-scone-variety-show https://blackdiamondfm.com/programmes/wee-scone-variety-show