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Shortwave radio is more challenging than you might imagine. Near to the transmitter it's received by ground wave, further it's scattered off the ionosphere. In
by rustyhancock 6mo ago
Shortwave radio is more challenging than you might imagine.
Near to the transmitter it's received by ground wave, further it's scattered off the ionosphere. In-between it's undetectable due to the skip zone. This might also explain why Amelia Earhart went missing [1]
Coverage is obtained from multipath and reflections. Leading to variable strength and timing. Not as bad as DXing on HF with low power but much harder than you might imagine.
Fine for someone to transcribe some numbers but useless for people trying to identify sources.
So locally you get an apparent direction to the source which is clearly not the source.
Add to that the complex local terrain and a well placed number stations can be very difficult to locate with precision.
Edit: unrelated but interesting there are some mysteries in HF transmission including long delayed echoes where a signal takes far longer than reasonable to travel out and back over several seconds [0] which given its travelling light milliseconds is a conundrum.
[0] https://en.wikipedia.org/wiki/Long_delayed_echo https://en.wikipedia.org/wiki/Long_delayed_echo
[1] https://youtu.be/zTDFhWWPZ4Q?si=Ib8jfbdNP-sLHM0B https://youtu.be/zTDFhWWPZ4Q?si=Ib8jfbdNP-sLHM0B
- Supermancho 6mo agoMy father regailed tales of his college years where it was a game to have a HAM radio operator start broadcasting and to have teams try to find where they were hiding, first. More challenging? Not really. It does require multiple boots on the ground to do it.
- srean 6mo agoThis seems to be a common treasure hunt game conducted by HAM clubs.
- Supermancho 6mo agoThat was it. Treasure hunt.
- xanderlewis 6mo agoAlso known as fox hunting.
- misnome 6mo agoPresumably doing it locally within a known few mile radius is different from nation-scale broadcast areas bounced from god-knows-where?
- Supermancho 6mo agoIf you can receive a shortwave signal, you can triangulate the source.
- srean 6mo agoReflections will pose a problem though. Two receivers of the same signal may not be from the same proximate source. One could from the original antenna the other from a reflection. Both could be reflected but by different reflectors. Even if the proximate source was the same for both the receivers, triangulation might yield the location of a virtual image of the original source. BTW I am just going by geometry and may be way off because radiowaves behave quite differently compared to visible light. One might need effectively the inverse of beamforming to nail it.
- rustyhancock 6mo agoExactly I have friends who have had voice contacts reflecting off aurora at VHF
- srean 6mo agoThat made my day. Thanks for the laughs.
- ted_dunning 6mo agoKP4MD detected wingtip vortices from reflected VHF signals. https://www.cfmilazzo.com/aircraft-wingtip-vortices https://www.cfmilazzo.com/aircraft-wingtip-vortices
- misnome 6mo agoSee content of post you initially replied in the context of: > Shortwave radio is more challenging than you might imagine.
- deleted 6mo ago[deleted]
- IAmBroom 6mo agoMultiple boots on Iranian ground is tricky for Americans right now.
- BenjiWiebe 6mo agoYes, more challenging. Ham radio fox hunting is usually VHF/UHF. Waaay easier to direction-find, since the signal isn't bouncing off the ionosphere, and also the much shorter wavelength means that you can get highly directional antennas that are small enough to be held, and don't need to be 50 feet in the air to work well.
- srean 6mo agoThanks that was quite illuminating. I knew about ionospheric reflections to be a problem but not the others.
- red_admiral 6mo agoI would guess that the combined EU/NATO counterintelligence forces could find the station if they wanted to, especially for the rough location in the article. EDIT: apparently the source is on a U.S. military base in Germany (other posts on this topic). Looks like its "ours" then.
- baxtr 6mo agoExplains why it’s still sending