I always hear this in discussions about number stations, but I don't think this is true in the US. In fact, I don't think I've ever seen a general consumer "shortwave radio". Unless the regular AM band counts, which seems to be medium wave.
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.
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.
More challenging? Not really. It does require multiple boots on the ground to do it.
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.
> Considering the topical interest in this station, the Priyom team shares its further expertise regarding V32's attribution, beyond being transmitted from a US military facility. While this remains unconfirmed speculation, and not facts, a prime candidate for the operator of this station would be the CIA. Contrary to popular belief, US intelligence has not entirely moved away from numbers stations. Sources in the intelligence community indicate that the CIA provides extra training about numbers stations and one-time pads to clandestine agents assigned to locations with a very hostile operating environment, such as Iran or North Korea: it is envisioned as a last-resort means of communication with high-value sources. So according to this, numbers stations are actually still an institutional part of the CIA playbook. The war in Iran, and the Internet blackout installed by the regime, fulfill the very circumstances for which the CIA would have planned this.
> We already know that the CIA has a significant presence in Iran and involvement in the war, having provided crucial intelligence tracking Iranian leaders that enabled the assassination strikes that kickstarted the war. They most probably have had a network of infiltrated assets already in place and organized, ready to be reached through a numbers station if need be right when the war started - which makes the CIA a candidate for running V32 consistent with a legitimate intelligence operation. However, what we've observed from V32's operations - technical quirks and shifting formats - suggest that the technical deployment of the numbers station and shortwave transmissions themselves may have been a little rushed by the circumstances.
> Another noteworthy feature of V32 is how all its transmissions take place on the same frequency. Most other numbers stations in general are comprehensive operations targeting many different recipients in different countries, and making use of many different transmission times and frequencies suited to the particular signal propagation needs corresponding to all those areas. In contrast, the fact that V32 always uses a single, same frequency, at always two given times of the day, would be consistent with an operation that only needs to target a single geographical area: Iran.
aswegs8•1h ago