Data transmission system for rail traffic control - has AC field used to carry stop signals modulated field indicating go signal

摘要

Data transmission system for railway traffic control signals transmits the signals from track-side units to the passing rail vehicles. The signal equivalent to a red stop light is represented by an a.c. field at high frequency and the signal equivalent to a green go light is represented by the same a.c. field modulated with an audio-frequency. Pref. the data handling system on the vehicles comprises a receiving antenna, a receiving filter, a receiver with demodulator, a level analyser, an audio-frequency analyser and a signal generator. Failure of the audio-frequency part of the system automatically means that the "go" signal is absent.