Transmission voie-machine
Transmission voie-machine (French: [tʁɑ̃smisjɔ̃ vwamaʃin]; TVM; 'Track-to-train transmission') is a form of in-cab signalling originally deployed in France and is mainly used on high-speed railway lines. TVM-300 was the first version, followed by TVM-430.
Source: Wikipedia — Transmission voie-machine (CC BY-SA 4.0)