Balise
A balise is an electronic beacon or transponder placed between the rails of a railway as part of an automatic train protection (ATP) system. The French word balise is used to distinguish these beacons from other kinds of beacons. Balises are used in the KVB signalling system installed on main lines of the French railway network, other than the high-speed Lignes à Grande Vitesse. Balises constitute an integral part of the European Train Control System, where they serve as "beacons" giving the exact location of a train. The ETCS signalling system is gradually being introduced on railways throughout the European Union. Balises are also used in the Chinese Train Control System versions CTCS-2 and CTCS-3 installed on high-speed rail lines in China, which is based on the European Train Control System. A balise which complies with the European Train Control System specification is called a Eurobalise. Overview A balise typically needs no power source. In response to radio frequency energy broadcast by a Balise Transmission Module mounted under a passing train, the balise either transmits information to the train (uplink) or receives information from the train (downlink, although this function is rarely used). The transmission rate of Eurobalises is sufficient