The main components of the ERTMS / ETCS L1 subsystem (SST) are as follows:
- 1. Encoders (or LEU, Lineside Electronic Unit), which are responsible for selecting and sending data (telegrams) containing information necessary for the correct management of the train, by directly interfacing with the lineside signals or signalling system. ECM's ERMTS encoders, signal post version or equipment room version, have been designed to operate with the ERTMS standard telegram format and interface with the EUROBALISE type transponders produced by different manufacturers.
- 2. Eurobalise transponders are used to transfer the information selected by the encoders to the train as well as information about the signalling scheme (engineering works, line gradients, speed restrictions etc.)