Abstract: The invention relates to an automatic aircraft landing guidance system having an electromagnetic detecting and locating device, positioned on the ground and a first multifunction transmitting/receiving radiofrequency beacon, on board each guided aircraft and transmitting in particular a continuous wave. The detecting and locating device uses the continuous wave transmitted by the beacon to perform a passive locating intended to improve the accuracy of the measurement of the angular position of the aircraft. It also comprises means for generating and periodically transmitting to the aircraft, via the beacon, information enabling said aircraft to rejoin an optimum landing path from its position. The invention applies more particularly to the guidance of autonomous and automatic aircraft such as drones in the approach and landing phase.

Abstract: The device for the elimination of intermediate frequency echoes from fixed targets carries out the cancellation of the echoes from the fixed targets by the storage, in the form of amplitude and phase samples, of the response to the first pulse of a burst reduced to video band, the synthesis on the basis of these samples of an intermediate frequency replica of the response to the first pulse of a burst and the subtraction of the synthesized replica from each of the subsequent pulses of the burst. It is of the double cancellation type, the preparation of the replica being done in two steps, a first rough-working step in which a rough replica is prepared and a second refining step in which the modelling error of the rough replica is taken into account.

Abstract: Disclosed is a method for the discriminating of obstacles by means of a radar, and its different applications to the measurement of a liquid in a tank or vessel, or again to the elimination of unwanted or parasitic echos coming notably from the ground, for radars mounted on vehicles or controlling vehicle traffic. To implement the method, the obstacle to be discriminated must have a substantially plane surface. The disclosed method then consists in successively transmitting substantially plane waves at slightly different angular frequencies .omega..sub.i, each wave being furthermore sent with two different polarizations p and p' chosen in such a way that these different coefficients of reflection on the obstacles according to the incidence of the waves give a criterion of discrimination. The processing at reception depends on the use (measurement of distance, elimination of parasitic echos etc.).