Abstract: The secure computer system comprises at least one computer having a processor operating under the control of a program on input data that can be associated with a code and delivering output data for output members. A security peripheral that is external but connected to the processor is provided to receive at least the input data codes, the operands, and the nature of the operation of each elementary operation performed by the processor, a code being calculated on each elementary operation performed by the processor in order to verify proper performance of all or part of the executed program. The system is applicable to processes for automatically running rail track systems.

Abstract: The installation comprises a roadway having at least some segments provided with longitudinal reference marking (10) for a nominal path, and vehicles (18) each carrying an assembly providing guidance by controlling a steering axle, having a module for forming an image of the road ahead of the vehicle (18) and for processing the image of the marking, and an optical guidance module calculating the orientation to be given to the wheels of the steering axle to follow the nominal path, and a steering servo-motor controlled by the guidance module. At at least certain segments of the road carry lateral guides (14, 16) and the vehicles, whose front axles at least are steering axles, are provided on each axle with vertical-axis guide wheels (24) designed to press against the guides (14, 16) in the event of the vehicle departing excessively from a nominal path on the road.

Abstract: The transmission system is designed for links between an infrastructure and moving bodies (10.sub.1, 10.sub.2) constrained to move along a determined path. The infrastructure has fixed transmitter/receiver stations distributed along the path, each having two transmitter/receivers allocated to two adjacent cells, e.g. (E'.sub.1, E.sub.2). The transmitters of two successive fixed stations allocated to the same cell are synchronized and they transmit using a coding system that is capable of tolerating or taking advantage of propagation over multiple paths.

Abstract: On the moving body, the apparatus comprises an active transponder, and on the track it comprises a passive responder. The transponder has an LF transmitter and an MF transmitter which, during displacement of the moving body, transmit to a zone through which the responder passes during said displacement. The responder has an LF receiver circuit and an MF receiver circuit having tuned radiating circuits that are associated so that an LF signal induced in the LF circuit causes the MF radiating circuit of the responder to be closed at the LF rate. The transponder responds to disturbances in the MF transmitter caused by the MF circuit of the responder being closed. The MF circuit of the responder includes two units having respective tuned radiating circuits that are strongly coupled together. Each is connected to a respective logic unit which, when excited, delivers a digital message causing the MF radiating circuit to be closed only for bits of a determined value in the digital message.