Submitted 10 hours ago by rudyharrelson@lemmy.radio to amateur_radio@lemmy.radio
https://lemmy.radio/pictrs/image/9039ff9f-f299-4f9b-b752-6891f7ebd0be.jpeg
Dunno if this is actually radio related, but thought this community might know something about it.
I was walking down a stretch of railroad that I haven’t explored before when I happened across this metal sign nailed down to the tracks.
It’s pointing toward the nearest railroad crossing and says “790Hz”. Is this a radio frequency one could listen on and hear when the train is passing by? Or something else? I don’t know anything about trains
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?
Did you tune in?
If it’s not something about signaling, it might be a resonance frequency - I could imagine sympathetic vibrations becoming problematic for the trackbed in spots due to the composition of the ground in some way, similar to earthquakes being able to liquefy soil.
sketchyenchantment@sh.itjust.works 9 hours ago
You should check out this patent. When the train goes over a special section of track, it will trigger the signal at the nearby crossing
rudyharrelson@lemmy.radio 1 hour ago
Ahh, that makes sense. Thanks for the assist!
in_my_honest_opinion@piefed.social 9 hours ago
790hz is the switching signal, as the contacts corrode the resistance increases so they have to be tested on a schedule.