Abstract: A simplified-fitting modular helmet resistant to aerodynamic stresses. The helmet has a base helmet and module, and includes between these two parts two lateral linking devices and an upper linking device. The linking devices include a finger secured to the module inserted into a socket secured to the base helmet and latchable in the assembled position of the helmet by a device of the quarter of a revolution type. The lateral fingers permit a small lateral clearance between the two parts of the helmet. Such a helmet may find particular application as an aircraft pilot helmet.

Abstract: The radar system of the invention uses a digital television network to make a multistatic configuration. The transmitted signal is of the OFDM type. The receiver or receivers carry out a matched filtering operation and recover the synchronization by processing of zero-value Doppler gates.

Abstract: In a method for the making of a secured document, a layer of bonder is prepared on at least one face of the document; one or more information elements and/or images are printed on a first face of an information transfer sheet; the first face of the information transfer sheet is applied to the layer of bonder of said face of the document. In this way, the information elements are printed on a transfer sheet that has no layer of bonder and yet there are obtained information elements that get merged into the layer of bonder.

Abstract: A fingerprint-reading system comprises a fingerprint sensor having an active surface sensitive to the pressure and temperature of a finger. The surface area of this sensor is far smaller than the surface area of the fingerprint to be read. The reading is done when the sensor and the finger are in contact and in a relative motion of sliding of the sensor and the finger with respect to each other. The system has means to reconstitute a complete image of the fingerprint from the partial images given by the sensor during this motion. Application inter alia to devices for the authentication of individuals.

Abstract: The disclosure relates to an optical disk of the type including at least one spiral track on which information marks are written in sectors whose addresses are substantially sequential along the track, wherein said disk includes a copy protection zone (PZ) comprising two parts of equal size each including a series of sectors designated by identical addresses on each of the two parts, the data written in this zone being shared between the sectors of the two parts, each sector of the zone also carrying an identifier (D1, D2) characteristic of the part to which the sector belongs, and specific protection data to enable verification of the presence and constitution of said protection zone (PZ) and to enable use of the data written in this zone, at least part of said specific protection data being recorded on said disk. The invention is notably applicable to anti-piracy protection of CD-ROM and DVD-ROM type disks.

Abstract: A magnetic sensor having a layer of nonmagnetic insulator including at least one layer of ferromagnetic particles. This combination of layers is sandwiched between two ferromagnetic electrodes. Electrons are transported by the tunneling effect between each electrode and the ferromagnetic particles. The tunneling resistance depends on the orientation of the magnetization of the electrodes and therefore varies in the presence of the magnetic field. The multichannel and multistage nature of the tunneling conduction eliminates the problems of short-circuiting by porosity, thus leading to less difficult fabrication and improved robustness in terms of breakdown. The possible thermal fluctuations of the magnetic moments of the aggregates can be suppressed by the choice of a magnetic material for the part of the insulating layer which contains the aggregates.

Abstract: This invention relates to a high voltage resistance. The resistance comprises at least one organic substrate (21) and a flat conductor (22) with length L, width l fixed to the organic substrate and with a given resistivity &rgr; and a thickness &egr;, the value R of the resistance being equal to &rgr;L/le, the values of the length L, width l being defined such that the mass of the flat conductor (22) is sufficient to resist electrical arcing without exceeding a given temperature. This invention is particularly applicable for current limitation resistances in microwave progressive wave tube emitters, used for example in airborne radar systems.

Abstract: A holographic projection screen for large screen projection and back projection with a liquid crystal projector. The screen includes at least one layer made of a photosensitive material in which at least one index grating may be recorded by an interference of an optical recording wave with an optical object wave. The thickness of the layer is equal to or greater than n0&Lgr;2/2&pgr;, where n0 is the average index of the photosensitive material, &Lgr; is the average spacing of the index grating and &lgr; is the recording wavelength.

Abstract: A fingerprint-reading system includes a fingerprint sensor having an active surface sensitive to the pressure and temperature of a finger. The surface area of this sensor is far smaller than the surface area of the fingerprint to be read. The reading is done when the sensor and the finger are in contact and in a relative motion of sliding of the sensor and the finger with respect to each other. The system reconstitutes a complete image of the fingerprint from the partial images given by the sensor during this motion.

Abstract: A power supply device (201) for a light box (102) is provided for the backlighting of liquid crystal display screens. The device (201) includes a regulating DC/DC converter (204) of the booster type, powered directly by a 28-volt power supply so as to deliver directly a 50-volt stabilized DC voltage for powering the light box (102). The converter (204) includes an output diode (208) which protects the device. An energy reserve is obtained via a capacitor (209) supplied directly with the 50-volt voltage. A second converter (111) with galvanic isolation provides a set of supply voltages to electronic control cards (103) of display screens illuminated by the light box (102). A link between the light box (102) and the control cards (103) is effected by a galvanic isolation device (210). The device (201) makes it possible to increase the efficiency of the power supply so as to decrease weight, volume and cost thereof.

Abstract: The disclosure pertains to methods of fast exploration in azimuth by a surveillance radar antenna and to radars implementing such methods. The method consists in driving, at slow speed, an antenna comprising two elementary electronic scanning antennas installed back to back, simultaneously controlling the electronic aiming of each elementary electronic scanning antenna, switching over the microwave signal sent alternatively between the two elementary electronic scanning antennas and, before each rotation of the radar beam, initializing the electronic aiming of each elementary electronic scanning antenna at a determined angle &thgr;i. The radar comprises an antenna with two elementary electronic scanning antennas and an aiming computer. Application especially to a sea patrol radar.

Abstract: The field is that of variable-modulo frequency dividers. To obtain a fast variable-modulo divider over a wide operating range the idea of the invention is to use twin flip-flops (1, 2; 3, 4; 5, 6; 7, 8) for the feedbacks. The benefit of this configuration is that it avoids the use of decoding gates between the flip-flops this increasing the propagation times of the feedback signals.

Abstract: A radio altimeter using a linear oscillator to transmit a saw-toothed signal comprises, in addition to this first oscillator, a second linear oscillator to transmit, in synchronism with the first linear oscillator, another saw-toothed signal with a given saw-tooth duration Td. The plateaux of the sawteeth of the two saw-toothed signals are at a distance from each other equal to a value f. The test consists in obtaining a height h′ by beats between the two saw-toothed signals and computing a standard height he=f.c.Td/dF.2 where c is the speed of light and dF the duration of each saw-tooth of the other signal. Application to all FM/CW radio altimeters.

Abstract: The proposed sample-and-hold device using a complementary bipolar technology comprises a follower input stage having an input receiving a voltage Vin to be sampled, at least one sampling circuit having a switching stage to be placed either in a first state called a “follower” state where its output follows the potential at its signal input or in a second state called an “isolated” state where its output is isolated from it signal input, the output of the switching stage being connected to the base of a first follower transistor whose emitter is connected to a terminal of an output sampling capacitor, the sampling circuit furthermore comprising a second transistor, having its emitter supplied by a current source and having its base connected to a potential copying that of the terminal of the output sampling capacitor, and a third transistor controlled by the digital command so as to be crossed by a current when the switching stage is in the <<isolated state>>, and so as to b

Abstract: A digital frequency synthesizer comprises means for the generation of the samples of a digital signal to be converted into an analog signal encoded on N bits as a function of a frequency control word, means for the generation of a noise signal encoded on N bits, and a digital-analog converter, the useful signal and the noise signal being truncated to M bits before being added up by an adder. The result of the addition is converted into analog signal form by the digital-analog converter. The generated noise has at least a noise density substantially equal to a law of equiprobability, this density being zero outside a given space. Application especially to direct digital synthesis, for example in the field of radar techniques or that of instrumentation.

Abstract: A process for managing intercellular transfers of communication in a cellular radio communication system. A specified number of microcells inside umbrella cells each respectively possess a base station for allowing the routing of the communications. Radio direction finding is used to pinpoint at least two successive virtual positions of the mobile stations in communication in relation to the base station of the umbrella cell in order to deduce therefrom a speed of movement of each mobile station in the time interval which separates the pinpointing of their positions. The speeds of movement which are obtained are compared to the specified speed values so as to entrust the management of the communication from a mobile station to the base station of the umbrella cell in which it lies when its speed is greater than the specified speed value, or to the base station of the microcells when it is not greater than the specified speed value.

Abstract: A device for the unambiguous measurement of the angle of roll of a projectile, comprises at least a radar equipped with means of processing and sending a signal to the casing of the projectile in at least one direction of incident polarization; a set of parallel grooves made on the casing, the depth of which is modulated dissymmetrically with respect to the axis of symmetry of the projectile; the axis of symmetry of the projectile not passing through the point of the antenna of the radar where the antenna beam is generated, the processing means analyzing, in reception, a signal back-scattered by the casing of the projectile, the signal being modulated as a function of the angle of roll of the projectile, the modulation having two maximum local values corresponding to two angular roll positions of the projectile such that the polarization {right arrow over (E)} is parallel to the grooves, the processing means removing the 180° ambiguity by comparing the levels of the local maximum values.

Abstract: A compact illumination device intended especially for illuminating an active matrix in a monochromatic or trichromatic display device. This device includes a source and collimating device in order to deliver a lighting direction from the source along a direction (Dy) and two optical components (M1) and (M2) which anamorphose the lighting in a direction parallel to the direction (Dy) and in a direction (Dz) perpendicular to the direction (Dy), respectively. These components may typically be of the holographic grating type operating in transmission or in reflection.

Abstract: A process for calculating on the one hand the coefficients of a spatial filter applied to the signals emanating from the third step and on the other hand the coefficients of a temporal filter applied to the replica signal, made up either of the known symbols for the learning sequences, or from the demodulated symbols for the information sequences, the coefficients of these two filters being calculated so as to minimize, under a specified constraint, a criterion of mean square error between the output signal from the spatial filter and the output signal from the temporal filter, and consisting in filtering the signals emanating from the third step with the aid of the thus calculated coefficients of the spatial filter, thus optimizing the gain of the array of sensors in the direction of the useful signal at the output of the spatial filtering and ensuring rejection of the interference.

Abstract: This optoelectronic system for the testing of a main antenna comprises: a test antenna designed to be placed in the field of transmission or reception of the main antenna; an optoelectronic component associated with the test antenna alternatively receiving and sending optical signals from/to remote transmitters/receivers and receiving and/or sending optical signals from/to the test antenna; an electric matching circuit connected between the optoelectronic component and the test antenna. This system thus enables the testing on the spot of an antenna (for example a radar antenna) without disturbing the radiation pattern of this antenna. This semiconductor component is therefore alternatively a modulator or a detector of light radiation, and it is connected by optical fibers to emitters and adapted detectors located out of the field of the antennas to be tested. The cables formed by dielectric materials do not disturb the radiation pattern of the antennas.