A monitoring device monitoring a railway track, including a track interface connecting the monitoring device to the railway track. Also included is a detector detecting a first track pulse having a first duration emitted on the railway track and received through the track interface. The detector can detect a start and end time of the first track pulse. A charger is connected to the detector and has an energy storage element. Further, there is an emitter emitting a second track pulse on the railway track through the track interface by using energy stored in the energy storage element and the detector can send a transmit control signal to the emitter.