#fleeting Trains have a transmitter attached to the back end which broadcast information about the air pressure and connection statuses. Things that used to be reported by a caboose. They broadcast a [[Digital Mode]] that could be decoded using an [[Software Defined Radio|SDR]], and a specification _must_ exist out there somewhere, but a quick search only yields a closed-ish-source application called [SoftEOT](https://groups.io/g/SoftEOT). These can be picked up on frequencies: - 452.9375 MHz for the locomotive side - 457.9375 MHz for the end-of-train device side This could be useful for detecting when a train is nearby, if you don't live near a siding or switching yard.  Source https://www.sigidwiki.com/wiki/End_of_Train_Device_(EOTD)