Abstract: The system according to the invention uses GPS/NAVSTAR navigation satellites and includes:a fixed station located in the vicinity of the landing zone, containing a receiver for positioning by satellite that gives an estimate of the position of this fixed station and computing means that give correction data representing the deviation between this estimate and a reference position; and a data transmitter transmitting, in particular, these correction data on a radio channel which is conventionally used to transmit data in a microwave landing system called the MLS system;an on-board station in each aircraft comprising: an MLS receiver capable of receiving the ancillary data transmitted by the MLS system, a receiver for positioning by satellite and a computing device by which the correction data can be used to correct an estimate of position given by the positioning receiver.

Abstract: The decoding circuit of the invention comprises essentially a digital filter 16, a pulse-width recognition circuit 17 a pulse peak amplitude selection circuit 23 and a circuit for decoding MLS boosted scanning pulse pairs 32 to 38. This decoding circuit makes it possible to eliminate parasite pulses from a clutter source whose width is incorrect when compared to the width of useful pulses and also to eliminate pulse pairs that have the right width but do not have the right interval.