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A ghostly radio station that no one claims to run

bbc.com

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Re: A ghostly radio station that no one claims to run

#61

Post by Neliquat »

simmons wrote: post #55
criddell wrote: post #4

I read this article last weekend and after reading it, I put batteries in my shortwave radio to see what was out there. Turns out, there's pretty much nothing. I couldn't hear anything on 4625 kHz. I let my receiver scan and when it was done I checked out what it detected and found absolutely nothing interesting. The most powerful signals were Christian broadcasts that had a kind of doomsday feeling about them. It se…

As others have mentioned, the time of day may have effected reception of the 4625 kHz station. However, in general, I've noticed that there seems to be far fewer stations received on the shortwave band these days, compared to the 1980's when I listened to shortwave a lot as a kid. I think this is because I'm using a low-end receiver with its built-in telescopic antenna instead of a more sophisticated SWL setup with a…

More noise to signal also.

Re: A ghostly radio station that no one claims to run

#62

Post by PoachedSausage »

DiabloD3 wrote: post #53
jankotek wrote: post #40

Earlier quoted context omitted.

No, it is not. The worst shortwave explanation I ever read. From BBC!

The irony is the BBC operates the best (and maybe only major commercial) shortwave stations in the world, as part of their AM radio service.

Most of the actual radio transmitters are no longer operated directly by the BBC. As far as I know the only site still under their operation is BBC World Service Atlantic Relay Station on Ascension Island. Whilst the BBC still produces the radio and TV programme content, in the UK the radio and TV transmitters are operated by Arqiva and World Service shortwave by Babcock. I was lucky enough to work on one of the last remaining operational high power longwave AM radio transmitters in the UK at Droitwich Transmitting Station. BBC Radio 4 longwave is broadcast at 500kW on 198kHz (locked to a HP 5065 Rubidium standard) and can be received in large parts of western europe.

Re: A ghostly radio station that no one claims to run

#63

Post by benashford »

criddell wrote: post #13
squarefoot wrote: post #8

Earlier quoted context omitted.

Night hours are best for shortwave reception. You could also need an external antenna depending on how far you are listening from. Another problem, probably the biggest one today, which affects reception on these frequencies (and generally on the HF bands) is the radio noise generated by many bad designed switching power supplies and appliances. Switching regulators (power supplies, converters, chargers etc.) for eff…

Thanks for the information. The shortwave frequencies still feel very underutilized. When I scan the FM (88 - 108 MHz) and AM (540-1600 kHz) radio frequencies, I pick up a lot of stuff. The shortwave band is relatively vast and feels very sparse. Considering how valuable spectrum is these days, it's hard to believe that we couldn't find a better use for it. Is it because it is so prone to noise that it's less valuabl…

There is more than one shortwave band, some are more useful than others and there are fairly large gaps between them, so it would feel sparse even if there were a lot of stations: https://en.wikipedia.org/wiki/Shortwave_bands

But as others have said, in many parts of the world there aren't many shortwave stations left. Africa and parts of Asia still have quite a few however.

Re: A ghostly radio station that no one claims to run

#64

Post by anfractuosity »

It sounds from the article they likely do know where the antennas are based?

If not, is it possible to use direction finding to obtain the location of antennas propagating shortwave frequencies?

(I assume this is more difficult due to the use of the ionosphere)

Also is there any remote chance the hardware attached to the aerial (power amps etc) could pick up unwanted RF or other interesting electrical interference and re-broadcast it, which may give some useful information.

Re: A ghostly radio station that no one claims to run

#65

Post by threeio »

besselheim wrote: post #35
wichert wrote: post #5

For the lazy who were hoping to find an audio clip in the article: you can find some here: http://www.sigidwiki.com/wiki/The_Buzzer_(ZhUOZ_MDZhB_UZB76)

The WebSDR at http://websdr.ewi.utwente.nl:8901 (based in the Netherlands) can be used to hear the station as it is broadcast. Set to 4625 kHz, USB.

More web based receivers are also available on http://sdr.hu and http://websdr.org

Re: A ghostly radio station that no one claims to run

#66

Post by askvictor »

What's to stop an adversary from broadcasting the same tone on the same frequency and overpowering the signal in certain areas? It strikes me that if the conjecture (of it being a reserved frequency for war time command signals) is correct, it would be relatively easy to break. Perhaps the weekly random words are some kind of authentication mechanism, but that seems like a long time to have to wait to authenticate the signal.

Re: A ghostly radio station that no one claims to run

#67

Post by KGIII »

criddell wrote: post #46
besselheim wrote: post #35

Earlier quoted context omitted.

The WebSDR at http://websdr.ewi.utwente.nl:8901 (based in the Netherlands) can be used to hear the station as it is broadcast. Set to 4625 kHz, USB.

Neato - it's picking up the buzzer station right now!

If you're unfamiliar, search for 'number station.' They are kinda neat and still in use.

Re: A ghostly radio station that no one claims to run

#68

Post by exabrial »

Qworg wrote: post #28
criddell wrote: post #27

Earlier quoted context omitted.

How were they able to pack so many digital radio stations on FM? Is it because it's higher frequency?

Yes, definitely. You can think of the trade off roughly as "frequency increases increase bandwidth and decrease penetration/range"

Until you get to x-rays! I've always wondered why this is

Re: A ghostly radio station that no one claims to run

#69

Post by KGIII »

tmearnest wrote: post #57
sillysaurus3 wrote: post #39

Earlier quoted context omitted.

Is it? If you imagine a fixed point in space, a short wave would mean more waves pass through it every second, not less. Short waves have more energy (they have bounce up and down more quickly) which allows them to travel further.

Shortwave, as in short with respect to "mediumwave" transmissions, like regular old broadcast AM radio, or "longwave" which can be used to communicate with submerged submarines. It's a really old term...

IIRC, subs use ELF or ULF. My understanding is that some of the older subs could trail a long wire antenna behind them.

It'd seem to me that the bandwidth for such would be abysmal.

Is this correct? I did take some EE courses but that was like forty years ago. All I have ever done with that is receive. I should probably learn more.

Re: A ghostly radio station that no one claims to run

#70

Post by soneil »

criddell wrote: post #4

I read this article last weekend and after reading it, I put batteries in my shortwave radio to see what was out there. Turns out, there's pretty much nothing. I couldn't hear anything on 4625 kHz. I let my receiver scan and when it was done I checked out what it detected and found absolutely nothing interesting. The most powerful signals were Christian broadcasts that had a kind of doomsday feeling about them. It se…

> It seems like there's a lot of underutilized spectrum.

There's some good reasons for this. HF is pretty challenging to fully utilize.

You have propagation that varies between "worldwide" (so it's difficult to assign new bands without ITU involvement), and "sunspot" (so you better have a plan B). And these variations aren't just over the duration of a sunspot cycle, but also over the day/night cycle.

eg, for maritime use, we have channel clusters at 2, 4, 6, 8, 12 and 16MHz. Which to use depends on the time of day the distance to the other station, and how much the sunspot cycle is messing with your first choice. Fun!

Then the physical challenges that arise from the ideal antenna length being proportional to the length of the wave. At 2.4GHz the challenge is precisely cutting your quarter-wave antenna to a fraction of a mm (31.25mm). At 2.4MHz same challenge becomes finding space for a 31.25m (~100feet) antenna.

Another big consideration is that these frequencies aren't particularly friendly to high-speed digital use. I suspect this is related to Nyquist theorem - the fewer waves you're receiving per second, the fewer symbols per second can be encoded into them.

And finally, some rather difficult legacy users. Aviation and Marine users who consider their usage life-or-death, radio amateurs that likely do too (heh), radio-navigation (I was reading about Loran making a comeback recently, to provide some backup when GPS is manipulated), over-the-horizon radar (which can be a lot like sharing a telephone call with a foghorn), etc.

All this taking up about as much bandwidth as one wifi channel ..

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