Abstract: The invention has as its goal a device for extremely precise localization of a train circulating on a railway, and necessitating no complex circuit on the ground. According to the invention, the apparatus comprises, on board the train and in front of its first axle, at least one tuned emitter fixed at an electromagnetic radio frequency, and a receiver provided with two detectors. On the ground, a passive loop tuned to the frequency used, is disposed between the two rails of the track, with the detectors and emitter being disposed in such a manner that there is not direct induction between them.

Abstract: A voltage variation detector is connected to a receiver which is associated with a transmitter inducing an alternating signal permanently in the rails of a railroad track and, accordingly, in a conductive loop positioned between the rails. The respective variations of the voltage induced in the loop and of a feeding voltage to the loop furnish redundant information of the presence of a car in the transmission zone.

Abstract: This disclosure is concerned with an alternating signal amplitude selection stage of particular application in devices for information transmission, as in track systems along which there are in succession a number of transmission zones each employing oscillating carrier frequencies, and with a view to avoiding crosstalk problems between signals in adjacent zones. According to the invention, the selection stage comprises an operational amplifier placed in an open loop, a counter of the number of impulse peaks included in the output signal of the differential amplifier, and a circuit for controlling the switching of an inverter to connect the appropriate filter to the input of a processing device for the signal of greater amplitude to eliminate the signal of lesser amplitude.

Abstract: The purpose of the invention is to reduce the total power consumed by a coupling for inducing a high-frequency alternating current in the rails of a railroad track for the purpose of transmitting information to trains traveling along the track.According to the invention, the coupling consists of two conductive coils made of a conductive strip attached to an insulating strip, the conductive strip being arrayed, in the portions of the coupling that are parallel to the rail, in a plane parallel to the sides of the central rib of the rail and on either side of it, the insulating strip separating the central rib of the rail from the conductive strip. The two coils are connected in such a way that the same current flows in the same direction through both.

Abstract: A method and apparatus for continuous supervision of both a vehicle's speed and deceleration over a track, provides overspeed detection in one set of conditions and under-deceleration detection under other conditions. The apparatus does not provide automatic driving, but is used in conjunction with either automatic driving equipment or manual driving of the vehicle. The process involved comprises the steps of transmitting to the vehicle an exit speed, defined as a speed limit to be observed on leaving a particular block section of the track upon which the vehicle travels. The exit speed is stored in the vehicle, and comparisons are made with a stored exit speed for the preceding block section. The process further includes a continuous measurement of both actual speed and deceleration of the vehicle, and provides for initiation of emergency braking dependent upon the results of the comparison and measurement steps.

Abstract: A method and apparatus is provided for communicating information in the form of plural items of data between a first station and a rail vehicle by transmission of pulses at predetermined repetition rates along railway tracks including a transmitting station for generating the information pulses having control apparatus receiving a particular data item as an input for selecting a repetition rate to represent the data item for transmission and generating apparatus connected to the control apparatus for generating the information pulses. The information pulses are coupled to railway tracks which transmit the generated information. A receiving station receives the information pulses from the tracks and includes sensing apparatus for sensing the information pulses and apparatus for removing interference signals received along with the information pulses, the interference signals being attributable to a number of causes which include unbalanced traction return currents and/or transmission interference.