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
8 Comments
sketchyenchantment@sh.itjust.works · 12 pts · 159d
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
in_my_honest_opinion@piefed.social · 8 pts · 159d
790hz is the switching signal, as the contacts corrode the resistance increases so they have to be tested on a schedule.
rudyharrelson@lemmy.radio · 2 pts · 159d
Ahh, that makes sense. Thanks for the assist!
vk6flab@lemmy.radio · 3 pts · 158d
The technology that's possibly in use on the railway is:
https://assets.new.siemens.com/siemens/assets/api/uuid:c9dbe06e-5daf-426d-97e8-c1a03562da91/sie-bro-pso4000.pdf
Evil_Shrubbery@thelemmy.club · 2 pts · 159d
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?
TropicalDingdong@lemmy.world · 2 pts · 159d
Did you tune in?
Multiplexer@discuss.tchncs.de · 1 pts · 159d
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 · 2 pts · 158d
RF happens at plenty of lower frequencies:
https://en.wikipedia.org/wiki/Extremely_low_frequency