3. Technical innovations that have enabled ERTMS

3.1 One-off transmission: the eurobalise

In control systems for moving objects such as trains, it is necessary to have a reference marker with two objectives:

• calculate control curves accurately and reliably;

• position the mobile, because although the train follows the rails and therefore has only one degree of freedom, it still needs to be located on the axis of the track.

This tracking system uses a point information transmission technology comprising two components: a ground beacon and an on-board antenna.

The ground beacon (figure 6 ) is passive and stores its location references...