ETCS Level 1.
ETCS Level 1 is a cab signalling system that can be superimposed on the existing signalling system.
The fixed signalling system with national signalling and track-release system remains in place. The signal aspects are picked up from the track-side signals via signal adapters and telegram coders (LEU - lineside electronics units) and transmitted as a movement authority with route data to the vehicle at fixed points via Eurobalise beacons. The on-board computer continuously monitors and calculates the maximum speed and the braking curve from this data.
Because of the spot transmission of data, the train must travel over the Eurobalise to obtain the next movement authority. With the installation of additional Eurobalises ("infill balises") or a EuroLoop between the distant signal and main signal, the new signal aspect is transmitted continuously. The EuroLoop is an extension of the Eurobalise over a particular distance that basically allows data to be transmitted continuously to the vehicle over a cable emitting electromagnetic waves.