Safety coding process for track circuits

摘要

A process for coding track circuits allows particularly information to be transmitted to a vehicle travelling over a railway track divided into a succession of sections each equipped with a track circuit, in which each of the carrier frequencies for energizing the track circuits is frequency modulated by means of a number of modulation frequencies each representing a piece of information to be transmitted. This process includes the steps of comparing the modulation frequency obtained by demodulation of the modulated carrier frequency with another source of modulation so as to check that said modulation frequency is indeed correct, and to allow transmission of the modulated carrier frequency in the corresponding track circuit only when this check is positive. This process and device applies to high-speed railway trains.