The automatic train protection system (ATP) is a system that enables safe train operation through train detection, distance maintenance between trains according to the position of the preceding train, track information (position, curve, gradient, and speed limit, etc.).
Balise is a system that sends track site information to a train onboard system and is for interfacing between an onboard system and the LEU. It receives variable telegram information from the LEU, maintains information such as link, movement authority, slope, speed, and received signal error for each signal history and transmits necessary information to the train.