3 ms·

You can even use fiber-optic cables running in cable throughs next to the tracks to detect and track trains: https://www.dbsystel.de/dbsystel-en/Digital-Stories

• runjake 8mo ago
  Yep. And the DOM (Digital Optical Monitoring) in consumer fiber optic modules (eg. SFPs) is sensitive to detect stuff like this! I can tell when and where we have significant wind storms, because it oscillates the fiber lines on the poles in a particular way which in turn generates a graph with specific signal oscillations.