Abstract: The invention proposes a novel method for using the signals provided by an airborne FM/CW radio altimeter, allowing to perform an analysis of the ground overflown by an aircraft for the purpose of, for example, identifying it, or alternatively of recognizing it. The method of the invention consists in analyzing, in the frequency domain, the shape of the spectrum of the beat signal generated by said radio altimeter to characterize said ground so as to extract from it information relating to the reflectivity of said ground.

Abstract: A frequency synthesizer comprises a single phase-locked loop controlled by a reference clock formed by a voltage-controlled oscillator, a programmable divider with variable division rank M, a phase detector, and a loop filter. It also comprises a predetermined number n of fractional division structures, each implementing a frequency step Pi×FreF lower than the reference frequency Fref.

Abstract: Microwave circuits, namely the circuits relating to the transmission-reception part and to the filtering of the microwave transceiver, are mounted on one and the same multilayer printed circuit and their electromagnetic insulation comprises, firstly, elements of the printed circuit such as conductive tracks on one of the faces of the printed circuit, metallized holes drilled in the tracks and close to one another so as to fulfil the role of an electromagnetic barrier and, at least in the case of some of them, a conductive plate and, secondly, attached elements with, especially, a thick metal lattice surmounted by a lid, the lattice resting on the conductive tracks.

Abstract: The analysis of an image of the field of observation from a heat camera by bands of n lines prompts the appearance of streaks or "striping" in certain zones of the image, all these zones constituting a "striping space". The device for the implementation of the method includes means to determine a base of orthonormal functions H and V, generating a vector space of functions for which the values taken, at each point of the image, represent the luminance values of all the types of striping, means to modelize the striping exhibited by the image in determining the coefficients of distribution of this striping on the basic functions, means to synthesize the striping, in determining the luminance values of the striping from the coefficients of correlation and from the values of he basic functions, and, finally, means to substract the luminance values of the synthesized striping from the luminance values of the initial image.

Abstract: A binocular-type optical device for night as well as day vision. A night vision optical device is located in a central body. The night vision optical device includes an optical path which is folded through a pair of opposed holes in a central body containing the night vision device. Two lateral bodies are affixed to the central body, each lateral body having a hole facing the holes in the central body. One of the lateral bodies faces an oblong hole in the central body, and is rotatable with respect to the central body. Each of the lateral bodies includes a day vision optical system having an objective at one end and an eyepiece at another end. A mirror contained in each lateral body are adjustable to permit either the folded night vision optical path or the day vision optical path to be received by a pair of common eyepieces.

Abstract: The present invention concerns device for the acquisition of the angular position of mobile means of the type including a luminous source emitting an incident beam in a known direction and a reflecting surface attached to the mobile means. The device also includes an array of elementary charge coupled sensors positioned so as to be at least partly scanned by the reflected beam. The device includes in addition optical means for limiting the width of the incident beam. The said array is connected to an electronic circuit producing a digital signal varying according to the position and/or the number of elementary sensors illuminated by the reflected beam.

Abstract: The field of the disclosure is that of enlarging optical lenses and, more precisely, binocular optical systems designed to be inserted into the night-time channel of an observation system, between a light intensifier tube and an observer's eyes. The disclosure can be applied especially to observation instruments for armored vehicles and, notably, periscopes for tanks. The disclosed optical system for a binocular device is of the type constituted by two groups, a forward group and a rear group, the rear group being constituted by a bonded doublet with plane rear face comprising a convergent convex lens bonded to a divergent lens, the lenses of the bonded doublet having different and complementary dispersions to compensate for the chromatism, and the focal length of the doublet ranging from 0.85F to 1.05F, where F is the focal length of the binocular device.

Abstract: Apparatus and method to localize rectilinear contours in a digitized image for recognizing shapes at a scene. The gradient of the gray level function of the image at the position of each pixel is determined, and those pixels which constitute a contour pixel are identified. The identified contour pixels are complemented with filler pixels where discontinuities are found. The neighborhood of pixels about a contour pixel is compared with a series of characteristic pixel configurations to determine if a correspondence exists with the characteristic configurations. In this way, rectilinear contour pixels are identified.

Abstract: According to the method, after a step for the digital processing of the video signal of the image analyzed by rows, there is determined, for each row, on the basis of the distribution of the mean light energy values below and above each position of the row, a step modelling function, the jump position of which gives the position of the horizon in this row. The device used to implement this method includes a sampler of the video signal coupled with a flip flop memory through an accumulator which adds up the luminance values row by row, and a processor which, on the basis of the distribution of the mean light energy levels, computes the signal to be subtracted from the digital video signal by means of a subtractor. The disclosed method and device can be applied to the detection of the horizon from an image analyzed by columns or by lines.

Abstract: A system for detecting a hot spot in an infra-red detected landscape and which co-operates with a landscape scan system for converging towards an infra-red detector circuit a main beam emanating seriatim from various regions of the landscape; the system being characterized in that it comprises: optical filter means for preparing from the main beam consecutively in time at least two secondary beams each representing a part of the main beam spectrum; and a signal comparison circuit having an input connected to the detector circuit and whose output is the output of the system and which serves to compare the detector circuit signals corresponding to the various received secondary beams.

Abstract: An infrared objective device with optical achromatization and athermalization comprises a front convergent assembly having at least one divergent lens acting as a port and one convergent lens, and a rear divergent assembly comprising at least one divergent lens. These three lenses are chosen so as to be made of three different materials of the type that can be used in the 8 to 12 .mu.m spectral band. They may notably be made, respectively, of germanium, chalcogenide and zinc sulphide.

Abstract: A device automatically measures a distance relative to the longitudinal axis of a runway to be destroyed. This device comprises: a radar transmitter-receiver, at least one depointed antenna, distance-measuring gates, a threshold circuit and a computer circuit.

Abstract: An infrared thermographic optical scanner is comprised of a first optomechanical device fitted with an entrance objective, at least a raster scan element, and a plane of infrared detectors on which the infrared radiation is focused in the form of lines. Further, there is provided a second optomechanical device made up of an orientable tilted periscope-head mirror and a derotator. The derotator is maintained clamped with respect to the head mirror coupling means for operation in the panoramic mode in a predetermined first angular position such that all lines scanned are parallel to each other, the raster scanning movement being obtained by maintaining the position of the raster element fixed, and by simultaneously causing the rotation of the head mirror, and at half-speed, causing the rotation of the derotator.