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
The technology that’s possibly in use on the railway is:
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
790hz is the switching signal, as the contacts corrode the resistance increases so they have to be tested on a schedule.
Ahh, that makes sense. Thanks for the assist!
Maybe a wiki/Balise?
But that looks passive & without electronics, just a plate bolted down?
Maybe it is just a simple sign about the signaling frequency (of some nearby wires) to the nearby crossing or station?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?RF happens at plenty of lower frequencies:
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.
![[Question] Metal Sign on Railroad Says "790Hz"](https://lemmy.radio/pictrs/image/9039ff9f-f299-4f9b-b752-6891f7ebd0be.jpeg){kind=link}