Abstract: A method of locating an aircraft in flight by means of a locating device including at least one sensor and a radar, the method including a first phase of determining a position of the aircraft, referred to as the first position, by means of the at least one sensor according to a signal supplied by the at least one sensor, a second phase of determining, at the same time as the first determination phase, a position of the aircraft, referred to as the second position, by means of the radar, and a phase of comparing data associated with the first position and data associated with the second position after which the first position is either validated or invalidated.

Abstract: A method for processing coherent MIMO radar processing DDMA waveforms includes: generating waveforms on transmitters, the waveforms, modulo the pulse repetition frequency, being identical from one transmitter to the next, to within a phase ramp specific to each transmit path; generating, for at least one receiver, a Range-Doppler representation of echoes of transmitted waveforms, where, for each receiver, echoes of a transmitter occupy at least one frequency cell in the Doppler spectrum, each signal band specific to a transmitter, placement of the signal bands in the Doppler spectrum being determined by phase ramp applied to each transmitter, the waveforms generated to leave a portion of Doppler spectrum between two signal bands unoccupied; identifying the transmitter corresponding to each signal band, due to Range-Doppler representation of echoes of transmitted waveforms. The method is suitable for the millimetre band, automotive or aircraft radar, for detection of target relative to the carrier.

Abstract: The invention relates to a system and a method for automatically harmonizing the position and/or orientation between an apparatus on board a mobile carrier and a reference frame of said mobile carrier, said mobile carrier being provided with an inertial unit able to provide measurements in the reference frame. The system comprises: at least one accelerometer mechanically coupled to the onboard apparatus, and providing acceleration measurements in a reference frame referred to as the associated onboard apparatus, a reception unit configured to receive measurements provided by said inertial unit and measurements provided by the accelerometer, a computing unit configured to calculate values of parameters defining a geometric transformation for conversion of data from the reference frame of the carrier and the reference frame of the onboard apparatus, from the measurements, carried out for at least two different flight orientations, by said inertial unit and by said accelerometer.

Abstract: A method for creating a virtual reception channel in a radar system includes an antenna possessing two physical reception channels (1r, 2r) spaced apart by a distance d in a direction x, two emission channels (1e, 2e) spaced apart by the same distance d in the same direction x and processing means, the method comprising: dynamically selecting two different waveforms, the waveforms being orthogonal to each other; generating a radar pulse of given central wavelength in each emission channel, each of the emission channels emitting one of the two different waveforms; acquiring with the reception channels echoes due to pulses emitted by the emission channels and reflected by at least one target; compressing the pulses by matched filtering of the echoes acquired by each physical reception channel, this involving correlating them with each of the waveforms generated in the emission channel; and repeating steps a) to c) while randomly changing one of the values of each of the phase codes associated with the generated

Abstract: A method and a device for measuring altitude of an aircraft relative to a point on the ground, said aircraft carrying a radar system comprising a directional antenna to transmit a radio frequency signal along a aiming axis, including. controlling the transmission of a radiofrequency signal along the axis, calculating received powers as a function of radial distance on a sum channel and an elevation deviation channel, calculating tilt angular deviation values, determining an estimator of the radial distance of the aircraft relative to the point on the ground intercepted by the aiming axis as a function of at least one zero crossing of the angular deviation measurement in a selected area of the angular deviation measurement curve, calculating an aircraft altitude relative to said point on the ground as a function of the estimator of the radial distance and the elevation angle of the aiming axis.

Abstract: The present invention relates to a method for assisting the landing of an aircraft on a landing runway, the method comprising: detecting, by a radar, characteristic elements of the landing runway, determining the angular offset between the axis of the radar and the runway axis as a function of the coordinates of the characteristic elements detected, and determining, as a function of the angular offset determined and the coordinates of the characteristic elements detected: the distance of the orthogonal projection onto the runway axis from the horizontal projection of the radar, and the distance of the orthogonal projection onto the straight line passing through the runway threshold from the horizontal projection of the radar.

Abstract: A radar imaging method using an active antenna comprising N transmission channels and M reception channels, transmitting in bursts of pointing cycles, is disclosed. The antenna covers a given angular range during a detection time unit of duration T, said time unit corresponds to a burst in which the N transmission channels are focused successively in a number De of pointing directions (di) such that: the pointing direction on transmission (di) is modified from recurrence to recurrence; each time unit of duration T comprising a periodic repetition of a number C of identical pointing cycles, each of these cycles comprising a number P of recurrences, the set of these P recurrences covers the De pointing directions (di); at least one beam is formed in reception on each recurrence in a direction included in the angular range focused on transmission in the pointing direction corresponding to said recurrence.

Abstract: A method for optimizing the elevational pointing of an antenna of an airborne radar system at an altitude h includes an antenna and processing and calculation means, the method comprising: a. selecting an area of interest b. calculating atmospheric losses Lref at a reference altitude href at the reference range Dref and calculating a reference criterion Kref=?40 log10 (Dref); c. for each possible elevational pointing distance of the antenna Dpt from the area of interest, calculating the antenna elevation S that makes it possible to target the distance Dpt via the centre of the antenna; d. for each distance D from the region of interest, calculating the angle ? at which the antenna observes the point of the ground at the distance D and calculating a criterion; 1. K(D)=Ge(?)+Gr(?)?40 log10 D+Lref(href,Dref)?Latmo(h,D) 2. where Ge(?),Gr(?) are respectively the gains of the antenna that are normalized at emission and at reception; e.

Abstract: A method for active neutralization of the effect of the vibrations of a rotary-wing aircraft for a monostatic Doppler radar includes a first step of measuring and temporally extrapolating the vibration modes at the transmitting-receiving radar antenna, using a 3-axis vibration sensor, fixed to the antenna and near the phase centre of the antenna; then a second step of estimating the expected movements of the transmitting-receiving antenna or of the first transmitting antenna and the second receiving antenna; then a third step of compensating the expected movements of the transmission radar antenna in the transmission chain or in the reception chain of the radar transmitter, wherein the projection of the movement vector of the phase centre O on an aiming direction is calculated to determine the value of the compensation phase shift to be applied.

Abstract: A method for processing coherent MIMO radar processing DDMA waveforms and includes NTX transmitters and NRX receivers, comprising the steps of a) generating waveforms on at most NTX transmitters, the waveforms, modulo the pulse repetition frequency Fr, being identical from one transmitter to the next, to within a phase ramp specific to each transmit path; b) generating, for at least one receiver, a Range-Doppler representation of the echoes of the transmitted waveforms, where, for each receiver, the echoes of a transmitter over a plurality of range cells occupy at least one frequency cell in the Doppler spectrum, called signal band, each signal band being specific to one of the transmitters, the placement of the signal bands in the Doppler spectrum being determined according to the phase ramp applied to each transmitter, the waveforms being generated so as to leave a portion of the Doppler spectrum between two signal bands unoccupied; c) identifying the transmitter corresponding to each signal band, on the ba

Abstract: The echoes being picked up in the distance-speed domain, the method being wherein it includes a step of producing a mask, in the distance-speed plane, overlying the zone of detection of the ground and/or sea clutter echoes picked up by the sidelobes, the zone being determinable by the antenna parameters of the radar, the waveform emitted by the radar and the environmental context of the radar, all the points of the distance-speed plane which are covered by the mask being assigned a characteristic which is specific to the mask; a step of filtering the received echoes, in which the echoes covered by the mask are rejected from the radar reception processing.

Abstract: The SAR is provided formed from a plurality of elementary images issued from successive emission spots, the elementary images overlapping zones of overlap, the measurement of the off-pointing is carried out on the basis of the difference between the energies received from two successive spots in a zone of overlap, the compensation being applied to the antenna reception gain in light of the measurement.

Abstract: A method for active neutralization of the effect of the vibrations of a rotary-wing aircraft for a monostatic Doppler radar includes a first step of measuring and temporally extrapolating the vibration modes at the transmitting-receiving radar antenna, using a 3-axis vibration sensor, fixed to the antenna and near the phase centre of the antenna; then a second step of estimating the expected movements of the transmitting-receiving antenna or of the first transmitting antenna and the second receiving antenna; then a third step of compensating the expected movements of the transmission radar antenna in the transmission chain or in the reception chain of the radar transmitter, wherein the projection of the movement vector of the phase centre O on an aiming direction is calculated to determine the value of the compensation phase shift to be applied.

Abstract: A method for creating a virtual reception channel in a radar system includes an antenna possessing two physical reception channels (1r, 2r) spaced apart by a distance d in a direction x, two emission channels (1e, 2e) spaced apart by the same distance d in the same direction x and processing means, the method comprising: dynamically selecting two different waveforms, the waveforms being orthogonal to each other; generating a radar pulse of given central wavelength in each emission channel, each of the emission channels emitting one of the two different waveforms; acquiring with the reception channels echoes due to pulses emitted by the emission channels and reflected by at least one target; compressing the pulses by matched filtering of the echoes acquired by each physical reception channel, this involving correlating them with each of the waveforms generated in the emission channel; and repeating steps a) to c) while randomly changing one of the values of each of the phase codes associated with the generated

Abstract: A method for optimizing the elevational pointing of an antenna of an airborne radar system at an altitude h includes an antenna and processing and calculation means, the method comprising: a. selecting an area of interest b. calculating atmospheric losses Lref at a reference altitude href at the reference range Dref and calculating a reference criterion Kref=?40 log10(Dref); c. for each possible elevational pointing distance of the antenna Dpt from the area of interest, calculating the antenna elevation S that makes it possible to target the distance Dpt via the centre of the antenna; d. for each distance D from the region of interest, calculating the angle ? at which the antenna observes the point of the ground at the distance D and calculating a criterion; 1. K(D)=Ge(?)+Gr(?)?40 log10D+Lref(href,Dref)?Latmo(h,D) 2. where Ge(?),Gr(?) are respectively the gains of the antenna that are normalized at emission and at reception; e.

Abstract: The echoes being picked up in the distance-speed domain, the method being wherein it includes a step of producing a mask, in the distance-speed plane, overlying the zone of detection of the ground and/or sea clutter echoes picked up by the sidelobes, the zone being determinable by the antenna parameters of the radar, the waveform emitted by the radar and the environmental context of the radar, all the points of the distance-speed plane which are covered by the mask being assigned a characteristic which is specific to the mask; a step of filtering the received echoes, in which the echoes covered by the mask are rejected from the radar reception processing.

Abstract: A method for determining parameters of a finite impulse response pulse compression filter, implemented by a multi-channel radar comprises: a step Etp10 of transmitting a calibration signal and of acquiring this calibration signal after propagation through the transmission channel, a step Etp20 of injecting the signal acquired, at the input of each of the reception channels, a step Etp30 of measuring the signal at the output of each reception channel, a step Etp40 of calculating the transfer function of the matched filters on the basis of the signals at the output of the reception channels, a step Etp50 of measuring the value of the average power at the output of the various reception channels and of calculating the relative gains between each of the reception channels and a predetermined reception channel on the basis of the measured values of average powers.

Abstract: The SAR is provided formed from a plurality of elementary images issued from successive emission spots, the elementary images overlapping zones of overlap, the measurement of the off-pointing is carried out on the basis of the difference between the energies received from two successive spots in a zone of overlap, the compensation being applied to the antenna reception gain in light of the measurement.

Abstract: A method for determining parameters of a finite impulse response pulse compression filter, implemented by a multi-channel radar comprises: a step Etp10 of transmitting a calibration signal and of acquiring this calibration signal after propagation through the transmission channel, a step Etp20 of injecting the signal acquired, at the input of each of the reception channels, a step Etp30 of measuring the signal at the output of each reception channel, a step Etp40 of calculating the transfer function of the matched filters on the basis of the signals at the output of the reception channels, a step Etp50 of measuring the value of the average power at the output of the various reception channels and of calculating the relative gains between each of the reception channels and a predetermined reception channel on the basis of the measured values of average powers.

Abstract: The present invention relates to radars and sonars, and more particularly to a synthetic-band technique of pulse compression making it possible to reach a very high distance resolution. Synthetic band consists in transmitting a waveform pattern consisting of a string of N coherent elementary pulses, linearly frequency-modulated, following one another at a recurrence frequency F.sub.r, of rectangular frequency spectra of elementary band B and of stepped carrier frequencies such that their frequency spectra will link up exactly one ahead of another to form a global spectrum of width N.times.B. On reception, the frequency spectra of the signals received in return for the N elementary pulses of a pattern are extracted by calculation, translated and juxtaposed so as to reconstruct a global frequency spectrum of width N.times.B and then compressed. Pulse compression is thus obtained which is equivalent to that which would result from the transmission of a waveform having a single pulse of frequency band N.times.