Long wave radio fans mourn fading frequencies (2023) | Hacker News Reader

Long wave radio fans mourn fading frequencies (2023)

bbc.com

79 pointsaustinallegro43 comments

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?)

I recently began delving into radio bands like SW, MW, and LW again after decades of abstinence. Here in Europe, there's a shocking amount of propaganda on these bands, most of it Chinese in various languages. You will barely find anything in English, German or French that is not leaning towards China or Russia, except for that American christian radio station talking about Jesus.

It appears that the west has decided to leave those air bands to foreign influences. Those propaganda stations also do not appear to care much wether a band is deemed an amateur band in your country or not.

"sincerely hope that if the remaining stations shut down, the band will become an amateur band."

I would sincerely hope so too. Moreover, if or when the BBC closes its longwave service it'll bring serious pressure on the few remaining countries to close their LW services.

With the abandonment of the LW Service the Band will be up for grabs and there will be pressure on WRC/ITU to reallocate the spectrum. My guess is that's likely happening already but these days I'm not close enough to the ground to know. So I'd strongly urge Amateurs everywhere to start campaigning before it's too late.

I'm an ex-amateur but I still strongly believe in the movement and its objectives, and I think that if or when—more likely when—the LW service officially closes (by WRC-set deadline) then the Amateurs should be ready to immediately step in.

No doubt there will be pressure from others (possibility stockbrokers wanting to take advantage of the ionosphere beating fibre in transmission speed around the globe for their ultrafast stock trading), so I'd expect there to be a real bun-fight for this valuable LF spectrum.

Personally, if or when reallocated I'd like this Band to go to scientific research and this is where amateurs could step in to help, here they'd share the Band with scientific researchers. One such example which I've raised on HN before is earthquake prediction. It's already known that in many instances that before earthquakes ocurr the crystalline rock structure is under such pressure that it can generate piezoelectric fields and these can affect the height of ionosphere and in turn the distance it reflects RF transmissions will change. This effect is most noticeable at very low frequencies and can be detected.

A network of stations would be needed around the world to monitor these frequencies constantly and the Amateur Service could provide this.

There are other options too. Even though I'm no longer involved in Amateur Radio I'm concernd with its flagging numbers (I suppose once a member of the Amateur fraternity always a member). As an alternative to the BBC's closure, I even see ways for the Amateur Service to make money, perhaps Amateurs could not only mod the BBC's transmitters but do so a at vastly reduced cost then actually run the stations at reduced cost (see my other post to this story). The BBC could justify this unorthodox approach on both maintenance and running costs and that the LW Service is now less important given the low number of listeners (maintaining the uptime percentage would be less important, etc.).

BTW, I expressed my concern about the Amateur Service's flagging numbers on HN only yesterday: https://news.ycombinator.com/item?id=41949118

What are "flagging numbers"? I've had my amateur radio certification (Basic w/Honours in Canada) for a few years but never heard this term before.

It’s an expression that is equivalent to “declining numbers” or “fewer and fewer”

"flagging", adj. becoming tired or less dynamic; declining in strength.

Oh wow, I had never heard the word used before in that way -- thanks!

I think LW transmission antennas are too large to be built bu amateurs

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-an...

and https://vk6ysf.com/t_antenna_arrangment.htm

[2]https://en.wikipedia.org/wiki/2200-meter_band#International_...

[3]https://en.wikipedia.org/wiki/LowFER

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

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

I am sure you mix long wave reception with shortwave reception, some different bands, wave lengths and propagation characteristics.

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 :\

"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.

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.)

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.

:-)

Transmitters need only be re-certified if they are to be sold in quantity.

Once-off Broadcast Transmitters need only demonstrate that they meet the relevant standards.

Many of the existing LF and MF BC transmitters were effectively custom built to meet the requirements of their transmit license (for example, the radiation pattern of the antenna were often unique for each station).

Does a VHF tetrode not have a lower bound on its operating frequency when operating at such a high power? Even if just an impedance mismatch at its terminals?

If I had to choose between the two for broadcast radio, keeping longwave radio transmissions makes more sense than AM (MW) radio. Keep FM (VHF) for local radio and lose the IBOC/DAB.

Can do, but Z is usually just a minor matching exercise. At those low frequencies it's not usually a problem. VHF tetrodes even make good high powered audio amplifiers. I've even seen them used in ultrasonics (~50kHz) when older original tubes weren't available.

Re second point, best options depend where you are geographically in the world, mix of services, etc. There's lots of different mixes/requirements.

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!

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-apo...

Also:

* https://en.wikipedia.org/wiki/Letters_of_last_resort

"…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).

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.

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.

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

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-...

https://coastview.org/2024/01/28/kfs-high-frequency-receiver...

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.

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..

username checks out. (sorry, couldn't resist)

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/

[2] https://blackdiamondfm.com/programmes/wee-scone-variety-show

Numbers stations aren't going anywhere soon.

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

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

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).

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).

Long wave != AM: long wave implies AM, but not vice versa (AM can be - and usually is - used on medium/short frequencies)

> 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.)

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.

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.

In the UK, you have a button on your radio that switches between AM FM and a third option? Or just those two?

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.

It's at a lower frequency, 148.5 to 283.5 kHz.

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.

Does my wavelength imply my modulation technique?

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.

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