Contrôle de vitesse par balises (KVB)
Contrôle de vitesse par balises (Speed control by beacons, abbreviated to KVB) is a railway safety system used in Mainland France and in the United Kingdom between London and the Channel Tunnel. The beacons themselves are placed trackside and store line information that is transmitted to the train as it passes over. A signal similar to the Eurobalise downlink is constantly transmitted from the train which energises the beacon, which will reply to the train using 50 kbaud FSKFrequency-Shift Keying with 58 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz). shift. A '1' is 692 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz). and a '0' is 750 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz)..
Frequencies[edit]
Clock downlink to beacon: 27.115 MHzMegaHertz (MHz) 10^6 Hz
Data uplink to train: 4.5 MHzMegaHertz (MHz) 10^6 Hz