Abstract: The wave is modulated in frequency (or in phase) and a measurement is made of the frequency of the beat between the transmitted wave and the received wave which gives the propagation delay and hence the distance. The method provides for the superimposing, on this modulation, of a periodic over-modulation with a period that is equal to or is a multiple of the propagation delay corresponding to a pre-selected expected distance. The device comprises, at transmission, in the case of a linear modulation of frequency, a saw-tooth generator (31) and a generator of over-modulations (32), for example sinusoidal, controlled by the expected distance given by a distance selector (30). The modulation signal of the transmitter is obtained by summation (33) of the signals of the two generators (31, 32).

Abstract: Back-projection display system including a screen which can be moved away from or, conversely, placed up against a support such as a wall, for example. A projector located at some distance away, on the ceiling for example, illuminates a back-projection mirror located at 45.degree. in relation to the illumination beam and in relation to the screen. The back-projection mirror itself is also articulated. In addition, the mirror may be made in the form of a holographic mirror.

Abstract: A polarization separator including a nematic liquid crystal (3) trapped between two transparent slides (1 and 2). The slide faces in contact with the liquid crystal are treated so that the liquid crystal molecules in contact with the faces are, for one of the faces (1) parallel to the face and, for the other face (2) perpendicular to the face. An incident light beam containing P polarization and S polarization is received at an oblique angle, and the directrix rotates the S polarization state as the light propagates through the device. The element is employed in a display system as a polarized light source.

Abstract: A receiver of satellite signals which features a reception chain coupled to a navigation processor. The reception chain is of a homodyne type and is formed by a single frequency-conversion stage followed by an amplifier chain coupled to an encoding circuit for encrypting the signals travelling between each amplifier before their transmission to the navigation computer. Such a device finds particular application in C/A code GPS satellite radionavigation system.

Abstract: In a method for the detection of the garbling of pulses received by a secondary radar, the secondary radar comprises a monopulse antenna that can be used to obtain a pulse power signal and a pulse difference measurement signal synchronous with the received pulses. The method consists in detecting, at the same time, ripples superimposed on the power signal and ripples superimposed on the difference measurement signal, the presence of at least two garbled pulses being detected by the presence of ripples on at least one of the two signals. Application to the reception circuits of secondary radars.

Abstract: A device and process for the control of a magnitude x by action on a control magnitude y is disclosed. Magnitude x has a one-to-one relationship with magnitude y when the value of a parameter h remains constant. Magnitude x is sensitive to and a one-to-one function of parameter h. Parameter h varies in a predetermined interval h.sub.m to h.sub.M, including reference value h.sub.i. A function y.sub.p =g.sub.p (h), which is the value given to the magnitude y to obtain the value x.sub.p when the parameter has a value h, can be defined for each value x.sub.p. The different functions g.sub.p (h) have a property wherein the value of a second function g'.sub.p (h) can be determined from the value of function g.sub.p (h) having the same value of parameter h, by the addition of a function of the difference between the real measured value h.sub.r and the reference value h.sub.i. Magnitude x is represented by the output magnitude of an operational amplifier having first and second inputs.

Abstract: A matrix display device using electro-optical material, wherein the material is inserted between two substrates, each comprising an array of electrodes. One of these arrays comprises transparent doped semiconductor zones acting as pixel electrodes surrounded by zones with little or no doping, constituting the channel of a control transistor, the electrode of which forms the source or the drain. The gate electrode may be formed as a ladder shaped structure over the channel in which the areas between the rungs are pixel electrodes.

Abstract: This invention makes use of the technique known as CFAR (Constant False Alarm Rate). Its objective is to create a method of adjusting the detection threshold of a radar consisting in:breaking down the area monitored by the radar in one sweep period, into sectors in which clutter can be assumed to be uniform,creating the histogram y(x) of received signal amplitudes in a sub-sample of distance-direction cells in each sector,in each sector, estimating the clutter histogram using a model m(x) defined analytically with coefficients adjusted so as to follow the shape of the recorded histogram y(x) at least in part of its variation interval, andcalculating the value of the detection threshold S in each sector starting from a set value of the false alarm probability Pfa and the model analytical equation using the relation: ##EQU1## where N is the total number of events contained in the modeled histogram. The invention is particularly appropriate for adjustment of the detection threshold of a marine patrol radar.

Abstract: An antenna having a "suspended stripline" structure with two metal plates encircling a dielectric film is disclosed. In this structure, a channel is made for a feeder of a slot with the end of a central conductor of the line penetrating a cavity whose thickness is approximately equal to that of the channel. The slot is made in the upper wall of the cavity.

Abstract: The disclosure relates to the making of the source and drain access regions of a field-effect transistor, these two regions being differentiated. The control region is defined by means of a three-layer mask of metal, resin and metal. A resin mask protects the drain access region, thus enabling the implantation of the source access region. After the dissolving of the resins, the drain access region is implanted.

Abstract: In a device for the reading of a set of resistive elements (1.0, . . . , 1.n) in which an interrogation potential (V.sub.0) is applied at each instant to an element while a reference potential (v) is applied to the other elements, a stabilization circuit (CS) operates to keep the reading ports (L.0, . . . , L.n) at the reference potential. The present invention may find particular application to the reading of the elementary magnetoresistive heads of a magnetic reading head.

Abstract: A detection and localization system mounted on an airborne vehicle, and which enables detection of objects having at least one face inclined relative to the surrounding flat horizontal ground and therefore presenting a contrast with this ground. A radar transceiver is connected to an antenna rotating around the airborne vehicle and has a low directivity in a pitch plane and a high directivity in a roll plane, associated with a generator of distance cells. Making use of mathematical relations, an on-board computer, knowing the altitude of the airborne vehicle and the roll angle of the emitted radar wave, localizes the inclined face which produces a much higher reflection of the emitted radar wave than the surrounding ground, to thereby detect the inclined face.

Abstract: The present invention relates to a method of binary encoding the N points of a constellation corresponding to the discrete positions, in amplitude and in phase, associated with the encoding of binary words in the case of a multicarrier modulation of OFDM type (Orthogonal Frequency Division Multiplexing) of a digitized signal. According to the method, two adjacent points of the constellation correspond to binary words which differ from one another by at most two bits. The present invention applies in particular to digital television.

Abstract: An electromagnetic wave detector comprises a stack of quantum wells included between an ohmic contact and a rectifier junction which may be a barrier (Al.sub.y Ga.sub.1-y As) with a forbidden band width that is greater than that of the barriers of the quantum wells.

Abstract: An object of the invention is the production of coaxial connections for the input/output links of the component and/or of the housing which encapsulates it.More precisely, the component placed in a package (B), is conventionally connected by wires to its package; the wires are next covered by a first insulating layer (21) then by a second conducting layer (24) in such a way that this second layer is linked to the earth pads (P.sub.E1) of the package. The layers (21, 24) thus form collectively-produced coaxial structures with the connection wires (F). A similar process is used for the input/output connections (P) of the package itself.

Abstract: A method for the optical writing of information elements uses a material (Ma) that is highly non-linear optically, on which it is possible to record information elements with sizes several times smaller than the writing wavelength. Also disclosed is a method for the reading of information elements recorded on a material (Ma) deposited on a material (Mb) capable of being the site of a stimulated emission generating the reading of the recorded information elements. Applications: high definition television, digital sound.

Abstract: A method and system for the avoidance of collisions among aircraft in which monochromatic radiation is transmitted from an aircraft fitted out with a wide-field optical transceiver. The monochromatic radiation scans the space around the aircraft which defines a zone of proximity. Optical radiation is returned after back reflection off objects which may be sources of danger constituted by other aircraft that have entered the zone of proximity. The radiation received is detected and then processed to deduce therefrom the direction and, as the case may be, the distance of the source of danger. Such a method can be applied especially to the avoidance of collision between non-cooperating aircraft.

Abstract: A device for automatic image segmentation according to the invention comprises a data processor associated with a network of automata organized in three levels; the inputs of each of the automata are weighted by adjustable coefficients; the number of automata of the first level is equal to the number of characteristic values computed from observation windows taken firstly in a set of examples of image zones having different textures. Learning by the network permits adjustment of the weighting coefficients of the automata of the network until all the examples of the same texture lead to the same configuration.

Abstract: Sonars provided with an acoustically transparent antenna. In a sonar comprising deployable arms (2) provided with columns (4) distributed on a cylindrical surface, the invention provides for the doubling of said columns (7) situated at a small distance from the first columns and for the association of signals from hydrophones mounted in the columns so as to obtain for each pair of columns a cardioid characteristic simulating a baffled antenna. The invention makes possible the suppression of the rear lobe of an acoustically transparent antenna.

Abstract: A signal processing device used for processing images including an optical correlator combined with a neuonal processor.