Patent ID: 8469318

Claim:
An apparatus for detecting whether a given track section is occupied or free, comprising: at least one vehicle-side transmitter; trackside receiver pairs disposed at the ends of the track section, each receiver pair having first and second receivers separated in a track direction, said first and second receivers being operated in pulsed operation with a given minimum pulse duration, and said first and second receivers being disposed to receive signals from said at least one transmitter when the vehicle passes and said at least one transmitter is present within a coupling range between said at least one transmitter and said receivers; and an evaluation device connected to receive signals from said receivers; wherein a maximum travel distance is defined by a minimum pulse duration of said receivers and a maximum speed allowable on the given track section; and wherein a response of said first and second receivers during a passage of the vehicle within the coupling range between said at least one transmitter and said receivers plus the maximum travel distance is preset such that, when the coupling range increases as a result of a fault, responses of said receivers in said receiver pair intersect each other.