Abstract A device for detecting the position of a train on a railway track equipped with a centralized control over the travel of the train using a transmission cable having crossings or other means defining periodic phase inversions of the magnetic field of the cable. It comprises three antennas located underneath the floor of the locomotive of the train and aligned one after the other in the longitudinal direction of the track, a band-pass filter connected to each antenna, three phase detectors, each one having two inputs connected to the outputs of two of the band-pass filters in accordance with the three different possibilities, such phase detectors being arranged to deliver an output signal only when their input voltages are in phase opposition, a logic circuit having three inputs connected respectively to the outputs of the three phase detectors for detecting the direction of travel of the train, and a summing circuit for totalizing the number of marking points crossed by the train connected to the outputs of the logic circuit, such logic circuit having two outputs delivering counting and deduction signals to the summing circuit.
In a centralized train control system wherein a cable forming a loop is located between two rails of a track and fed by alternating currents and wherein said cable has crossings therein or other marking points defining periodic phase inversions of the magnetic field of the cable, which marking points are counted aboard the locomotive of a train in order to provide an indication of the distance traveled by the locomotive in the zone defined by the cable, a device for deducting from the marking points encountered in the normal direction of travel those encountered when going backward, comprising three antennas located underneath the floor of the locomotive and following each other in the direction of the track, means for comparing two-bytwo the phases of the voltages induced by the cable in the different antennas at the passage of a marking point and for delivering a logic output signal having the value 1 when the two compared phases are in opposition, means for detecting the order of succession of said logic signals and for delivering a counting signal or a deduction signal depending upon said order of succession, and means for summing said counting and deduction signals with their appropriate signs.
Claim 2
Dependent Claim
201 words
In a centralized train control system wherein a cable forming a loop is located between two rails of a track and fed by alternating currents and wherein said cable has crossings therein or other marking points defining periodic phase inversions of the magnetic field of the cable, which marking points are counted aboard the locomotive of a train in order to provide an indication of the distance traveled by the locomotive in the zone defined by the cable, a device for deducting from the marking points encountered in the normal direction of travel those encountered when going backward, comprising three antennas located underneath the floor of the locomotive and following each other in the direction of the track, means for comparing two-bytwo the phases of the voltages induced by the cable in the different antennas at the passage of a marking point and for delivering a logic output signal having the value 1 when the two compared phases are in opposition, means for detecting the order of succession of said logic signals and for delivering a counting signal or a deduction signal depending upon said order of succession, and means for summing said counting and deduction signals with their appropriate signs.
Claim 3
Dependent Claim
154 words
A device according to claim 1, wherein the locomotive has front and rear cabins which may be alternatively placed ahead of the train thereby reversing the order of succession of the signals delivered by the antennas, and further comprising means for detecting which one of the two extreme antennas is ahead of the train at the entry of the locomotive in the zone defined by the cable, means responsive to said detecting means for storing the state acquired by the antennas at the entry of the zone defined by the cable, and means responsive to said detecting means for inverting or not two of said logic input signals depending upon the order of succession of the signals delivered by the two extreme antennas at the passage of a marking point so as to obtain a correct counting depending on which one of the two driving cabins of the locomotive is ahead of the train.