Comment on [Question] Metal Sign on Railroad Says "790Hz"
Multiplexer@discuss.tchncs.de 4 weeks ago
Definitely not an RF frequency, much, much too low.
Might be some wire based signalling for a railway switch or semaphore or so.
Perhaps ask in a train community?
vk6flab@lemmy.radio 4 weeks ago
RF happens at plenty of lower frequencies:
en.wikipedia.org/wiki/Extremely_low_frequency