Showing papers by "Matra published in 1975"

System for detecting the presence of a possibly moving object

Abstract: A system for detecting the distance L between two objects A and B, either or both of which may be in motion, comprising approach detector means and proximity detector means operational within overlapping distance ranges; each detector means includes an emitter mounted on a first one of the objects, which radiates a primary signal toward the second object, a responder on the second object, which radiates a similar secondary signal back toward the first object, and a signal comparator for measuring the time differential between the primary and secondary signals to determine the distance L between the objects. A range switch coupled to both comparators develops an output indicative of the distance L within a comprehensive distance range encompassing both the approach range and the proximity range and extending down to zero distance.

Anti-collision safety device for a passenger transport system on tracks

Abstract: An anti-collision safety control for vehicles travelling on tracks; the control comprises two safety loops per vehicle, linked to two common loops in a central control station. Each vehicle loop comprises control circuits for determining the distance to the next preceding vehicle, for determining a safe stopping distance for the vehicle, and for stopping the vehicle if the distance to the preceding vehicle becomes smaller than the safe stopping distance or if there is a failure of a safety circuit. The distance control circuit comprises a detector for detecting reference points provided along the track, a counter for calculating the distance of a vehicle from a given zero location, and a delay circuit for converting this distance into a position signal timed to a synchronization pulse received by all vehicles. Position signals from all vehicles are transmitted to the central control and back to the vehicles; the distance to an immediately preceding vehicle is determined by comparing the position pulses.

Methods and devices for stabilizing the rest frequency of frequency modulated oscillators

Abstract: The rest frequency of an oscillator supplying a sub-carrier modulated in frequency by the chrominance signal from a SECAM television transmitter, is servocoupled to a reference frequency during the frame return periods and a phase shift of the oscillator is effected during the line return periods, shorter than the frame return periods. The servocoupling device comprises a reference frequency generator, and a servocoupling loop comprising a switch member and storage means for storing a parameter which controls the rest frequency of the ocillator, and control means for actuating the switch into closed condition, so closing the loop during the frame sweep return periods. The oscillator comprises means for phase setting during line return periods, shorter than the frame return periods.