You need two transistors, a ferrite coil and a small set of simpler elements. And it is so simple you can actually explain what every part of the circuit does.
And then the reward... Once built you could listen to BBC regardless of where you are in Europe. My kids just LOVED IT, no Netflix K-Drama replaces this experience. My daughter was listening to BBC on her radio every night going to sleep.
Then we took away components until we had virtually nothing left, a diode I think(?), and still we had some signal.
Turns out there was a transmitter on the top of the hill the school was also on.
Fun times.
(but yes I do miss those simpler days - but I guess the basics now is making an Arduino flash an LED)
I was listening to DAB in the car, not so far from here last weekend, and it kept cutting out. Whereas you could get LW everywhere!
I developed a love of cricket on Test Match Special from a very young age. A tiny inexpensive radio could get it anywhere. I actually never minded the interruptions from the Shipping Forecast, the real reason they kept this service up for so long. I know there are many ways to get a forecast now, none of which is as reliable as radio 4.
In the HBO miniseries Generation Kill the marines are tuned into the beeb long wave to get news updates, and there's a cricket score read out in the first episode
https://www.reddit.com/r/generationkill/comments/6o2w2s/epis...
With apologies to Affabeck Lauder
That has a lot more to do with the dated implementation and less to do with digital radio. There are a number of digital broadcasting techniques which can minimize and compensate for noise, including a slight delay with a signal correction and fault tolerant codecs.
DAB was implemented using the old MPEG2 audio codec. DAB+ uses the now 15 year old codec HE-AAC which isn't really designed to handle corruption. Opus handles loss a lot better (see their examples https://opus-codec.org/examples/ )
And technically while some people do call it MPEG2, it's actually MP2, also known as MPEG-1 Audio Layer 2, an audio codec in the same family as MP3 (MPEG-1 Audio Layer 3).
I imagine that today they'd probably use something like Opus and a fountain code or similar, yes... But you can't expect everyone to replace their radio every 10-15 years ;)
Certainly not, which is why I believe DAB (no plus) is still floating around. And I'm not really suggesting that they made a bad choice.
I'm mostly pushing back on the notion that digital means all or nothing audio. If broadcast audio stays alive (which it may not) then I hope the next standard is opus, fountain codes, and QAM-64 or similar so we can stuff a bunch of bits into error correction while still having graceful degradation, better than analog, when the signal degrades.
(Also doesn’t analogue FM also kinda cut off fairly abruptly?)
This video gives a good example of the signal breaking down from 00:38
At the same quality dab is still perfectly long after fm becomes gabled. It then vanishes.
The problem with dab in early days was the lower strength, the poor quality decoding, and the lower bitratr than should be been used for the codec.
Haha. The DAB+ signals are compressed as much as possible.
Comparison here is FM, not FLAC.
Really soured me on this digital radio technology.
https://www.forcesnews.com/services/navy/nuclear-promise-let...
> The process by which a Trident submarine commander would determine if the British government continues to function includes, among other checks, establishing whether BBC Radio 4 continues broadcasting [on long wave]
> Submarines on patrol were reported to have briefly gone on nuclear alert in 2004 when Radio 4 went off the air for 15 minutes due to a power cut.
Or
mplayer 'https://a.files.bbci.co.uk/ms6/live/3441A116-B12E-4D2F-ACA8-C1984642FA4B/audio/simulcast/dash/nonuk/pc_hd_abr_v2/aks/bbc_radio_fourfm.mpd'
vlc 'https://lsn.lv/bbcradio.m3u8?station=bbc_radio_fourfm%22&bitrate=320000%22'
For about a year now, BBC has been aggressively geoblocking other radios.
- some cryptobro
/s
At least in VK/Australia, there’s the 2200 meter band, but it’s quite limited (1W power limit, CW/digital only, 135.7–137.8 kHz).
At the same time, as much as I don’t want the AM broadcast band to die, I’d love an amateur band in the lower/middle part of MF/MW.
I meant just the broadcast band 148.5-283.5 kHz. (Though I'd love if 2200m and 630m were just a bit wider.)
> and NDB beacons.
Good point[1]. So 148.5-200 kHz in ITU Region 2 (and keep LowFER allowances on 160-190kHz as a consolation prize.)
We've also got a chunk just off the bottom of MW around 475kHz, which ought to be good for long-range night-time communications. It's licenced for CW, QRSS, and narrow-band digital modes.
Doesn't GPS utterly replace this?
Building equipment that works on frequencies this low, and avoiding natural interference, can be extremely difficult.
My 7 Mhz antenna (HF, 40m band) is 67 feet long, and goes across by whole house.
The smallest antenna you could get away with for LF would be hundreds to thousands of feet long.
You might be able to go smaller if you enjoy suffering. Though, there are some pretty creative antenna designs that defy logic.
I wonder if you can couple to your local distribution grid, and not get arrested.
Coupling into my power upstairs is a bit of a problem sometimes though.
Pirating power is something I've heard that happens, but I looked it up, and couldn't find an actual cited example of someone doing it via induction.
Plenty of people doing it via extension cords and device tampering though.
The next logical step in that direction would be cracking down on HAM, not liberalization of it.
We'll see.
There's also high frequency firms that want to muscle their way into shortwave frequencies as they can have lower latency between trading sites (eg NYC and Chicago) since the physical infra isn't a direct link as the crow flies (as well as the speed of light being slowed in fiber optic lines). They've even restarted some microwave links, as they don't necessarily need a lot of bandwidth, just latency.
https://en.wikipedia.org/wiki/Letters_of_last_resort#:~:text...
https://en.wikipedia.org/wiki/List_of_longwave_radio_broadca...
I hope not. I am saving $80 per month by recording over-the-air TV using Tivo. I only want the major networks, and recording them over the air is free. Tivo DVR is great for OTA and their service is still active but sadly they have stopped selling their DVR.
Rather defensive press release thing from the BBC: https://www.bbc.com/mediacentre/articles/2026/radio-4-broadc...
At 30 ct/kWh, that's 300€ per hour, 7200€ per day and about 2.6 million € a year - for a customer base that is only decreasing.
[1] https://en.wikipedia.org/wiki/Droitwich_Transmitting_Station
And by the virtue of shortwave propagation, it could be heard across the world. For the past month and a half (from when the news of its impending shutdown was revealed) I was regularly picking it up in Australia right up until the bitter end.
In the MF (AM broadcast) band, you can observe this at night - in Australia I can pick up the 50kW Melbourne ABC station (public broadcaster) at 774kHz with a good radio, just about across the entire country.
In the LF (longwave) band, the earth’s surface and the ionosphere start to behave more like a waveguide than skywave. This is actually more reliable/consistent than even HF, but you need massive transmitting antennas due to the large wavelengths involved.
HF also generally wins for distance covered per watt - despite the massive power of Radio 4 longwave, I’d have no chance of hearing it reach Australia.
Bounce off ionosphere
Radio stations are usually measured by the last of those: Effective radiated power.
You can have a radio station with a 50,000 watt ERP, but running only a 2,500 watt transmitter.
For FM radio stations, it's all about the height of the transmitter above average terrain. For AM, it's about the ground conductivity and frequency.
I once worked at a 1,000-watt AM station that had a signal much larger and clearer signal than the 5,000-watt AM station a few miles away.
I'm not a radio engineer, but I'm sure there are plenty on HN who can correct and clarify what I've written.
My suspicion is that this means an exciter and a stack of amps per service, which then go through a two stage combiner and out to the antenna. There might even be a pair of exciters and amps per service depending on redundancy.
The combiners (certainly for FM/DAB/TV services) also cause cumulative attenuation as the signal gets combined each time, so even if all 3 are radiating at the same power, the first in the chain might need twice as much amplification to make up for losses.
edit: MB21 (of course) has some fantastic technical info about Droitwitch: https://tx.mb21.co.uk/gallery/gallerypage.php?txid=1454&page... and there's some great pics here, too: https://www.radiorewind.co.uk/radio1/droitwich.htm
I believe they're still using a pair of Marconi B6042 transmitters (250kW each, in parallel) to provide at least one of the services.
I was very much getting myself confused with some of their other transmission sites where they take multiple DAB or DTV services, modulate, amplify and combine them and then broadcast through the same antenna.
Going by [1], emitted power.
[1] https://www.bbceng.info/Operations/transmitter_ops/Reminisce...
Droitwitch LW's antenna uses a T-aerial suspended between two 210m steel masts acting as massive capacitive top-loaded vertical monopole. The signal isn't beamed or shaped, it propagates omnidirectionally and this style of antenna offers _0 dB_ of ERP increase.
Even worse, they're transmitting AM, so the power output dynamically increases with the volume of the analogue audio being transmitted. If you cut off the input to Droitwitch, it'd still be putting out a 500kW carrier wave. When audio is applied the amplitude of the carrier is modulated, so for peak loudness (someone shouting or the loudest spike in music) it can take an extra 50% power to create the upper and lower sidebands - at peak, the Vapotron tubes could be putting out a combined 750kW.
The amplification stage is only ~70% efficient as well, so at peak power it's possible that the site is pulling nearly 1MW from the grid.
--
Compared to a modern UHF DTV transmitter station the differences are wild. The big transmitter near me is putting out 6* DTV MUX's at 174kW ERP each, but that's through a 15dBd UHF array at the top of the mast which gives an obscene amount of gain.
- Mains draw at the wall ~150kW (including cooling and ancillary systems).
- Total TPO (RF energy leaving the cabs) from each of the six transmitters is only ~52kW combined (8.7kW each)
- Output of the combiners after losses of ~0.5dB is ~46kW. We can expect another ~1.5dB of attenuation after forcing it up 300m of waveguide to the top of the tower so we're now sat at a "mere" ~33kW of RF energy going into the bottom of our antenna.
- 33kW with a +15dBd gain gets us to an ERP from the antenna of 1.044 MW.
--------------
Note: Numbers compiled from public sources. All mistakes and misunderstandings are mine. Whilst I do work in a tangentially related industry this is completely out of my area of expertise - in the same way that working as a cleaner at an aeroplane does not mean one knows how to fly or maintain a plane.
Some people save energy by turning their appliances off at the plug rather than leaving them on standby. Clearly Radio 4 chose to avoid having Brian Blessed on too frequently instead ;)
I think the reason why its been left on so long is that it took so long to migrate to digital meters https://tradehelp.gdhv.co.uk/support/solutions/articles/7900...
I am also annoyed that I missed the last signal.
Listening to the last transmission there, I note that the continuity announcer, (the Irish) Al Ryan, signed off with 'oíche mhaith', i.e. 'goodnight' in Irish. A nice nod, I think, to all the former LW listeners in Ireland.
I miss the days of jingles.
The program was mostly the same as BBC Radio 4 but it used to diverge at certain times of day. I used to be woken up at 5am every day by my parents clock radio with the farming news which was very dull, but easy to sleep through.
In the USA there have never been commercial longwave stations, though various WWV time signals are broadcast in that band.
That, and Atlantic 252 (I believe now long gone) were what he woke up to every morning.
https://en.wikipedia.org/wiki/Atlantic_252
"Although the transmitter was in Ireland, the signal's reach meant that it was often looked upon as a "UK national station". Reception reports were received from such locations as Berlin, Finland, Ibiza and Moscow."
One can listen to the live closure broadcast via this WebSDR website, by tuning it to AM 198 kHz.
"You are listening to 198 kHz longwave. BBC Radio 4 is no longer available on this frequency. However, you can find Radio 4 many other ways. You can find BBC Radio 4 online, via BBC Sounds. Radio 4 is available on DAB digital radio and through your digital television, including freely. Radio 4 is also available via FM radio, on 92 to 95 MHz and 103 to 105 MHz. Plus, you can listen via your smart speaker: just say 'play Radio 4'. Information on how to listen can be found on the BBC website, at bbc.co.uk/reception."
> Given these factors, investing in upgrading the LW equipment is not considered a cost-effective solution for licence fee-funded services
And that's another problem - maybe the Government should step in and set up a proper Civil Defence-style warning/information system - we may well need it in a few years - it's a shame our official National Broadcaster can't fulfill the role.
Vacuum tubes also aren't vulnerable to nuclear weapon electro-magnetic pulses.
However, other than ham radio enthusiasts I guess no one listens to analogue radio anymore.
What it did provide was a simple but reliable way to maintain emergency broadcast to general public within Britain. And it probably should have been kept online just for that reason.
Even when they can most people Wouldn’t have a clue to listen to it.
There’s a reason LW isn’t critical national infrastructure.
If we did regain the capability it would probably be solid-state.
For that matter I'd be somewhat surprised if you can't simply buy a ready-made replacement.
No idea where vacuum tubes were invented but I'm sure the BBC could find someone to make them.
The BBC has just cut its budget by £500 million, in an apparent attempt to limit the damage from the latest charter renewal process - which determines its funding. The new director general (ie ceo) is an ex-Google person, and they seem to be pivoting to become a social media content provider. So I'm pretty sure that spending licence fee money on making vacuum tubes to broadcast a signal that nobody under forty listens to wouldnt get past a value for money test.
(I like the BBC and its radio output, and I'm one of those weirdos who still pays the licence fee despite never watching tv or any of the stuff that the licence fee is required for. But it is becoming increasingly lost to me: focussed on triviality and politically cowed. Sadly, I no longer expect it to last.)
If you only watch DVDs, or stream movies etc, you don't need a license
But there's virtually no inspections any more. There were a lot of bad newspaper headlines about poor single mothers going to prison for getting caught (and refusing to pay the fine, but that bit usually got left out), so enforcement basically ended.
This isn't about the little tubes that go in a guitar amp... we're talking about tubes that may well be too large for a single person to lift.
What's more, everyone who knew how to build things is either dead or in a retirement home. You'd have to re-engineer much of it from scratch.
Nixies are also cold cathode, low current devices. Radio broadcast tubes can be handling tens or even hundreds of thousands of watts.
At the moment they are running a goodbye loop, so you can still hear something.
At least there’s Radio Caroline still on 648kHz AM, so there will be a British voice still on the air.