Thales

Grégoire Pillet

Patrick Feneyrou

Jean Minet

Christian Renard

Isabelle Le Roy-Naneix

Adrien Glise

Stefan Varault

An array antenna (A) in a medium (M) comprises a plurality of radiating elements (ER) ensuring the transition between the antenna and the medium, the reflectivity of each element depending on a parameter, the reflectivity of a first element being close to that of the medium, the reflectivity of a last element being close to that of the antenna, the reflectivity parameter of the elements varying from one element to the next. A method comprises calculation of a path equal to the sum of the variations of the reflectivity from one element to the next element, optimization of the variation of the reflectivity parameter so that equivalent radar cross-section of the antenna is the lowest possible or the antenna best observes the radiation objectives, determination of the different elements as a function of said parameter, and simulation of the overall reflectivity and/or of the radiation of the antenna.

Method for integrating a 'network' antenna into a different electromagnetic medium, and associated antenna

A method for processing a signal from a coherent lidar includes a coherent source, the method comprising steps consisting of: generating a first beat signal and a second beat signal, using respectively a first detection assembly and a second detection assembly for a plurality of n time intervals, determining n respective values of spectral density using a transform in the frequency domain of the cross-correlation between the first and second beat signals, determining a mean value of the spectral density using said n values of spectral density, determining a piece of location information on the target using the mean value of said spectral density.

Method for processing a signal from a coherent lidar in order to reduce noise and related lidar system

A method for processing a signal arising from coherent lidar includes a coherent source that is periodically frequency-modulated; a beat signal being generated by photodetector on the basis of the interference between an optical signal that is referred to as the local oscillator having a local oscillator frequency (f(t)) and an optical signal that is backscattered by a target illuminated by the lidar, said beat signal being digitized; the local oscillator frequency (f(t)) being made up of the sum of a mean value (f0) and of a modulation frequency (f(t)) arising from the modulation of the source, the modulation frequency being periodic according to a modulation period (T), each period comprising n linear portions having n frequency slopes (&#x3b1;i), respectively, where n is greater than or equal to 2, the method comprising the steps consisting in: complexly modulating the beat signal; complexly demodulating the modulated signal (S) by n demodulation frequencies (f(i)) each having a single slope that is equal to the respective frequency slope (&#x3b1;i) of the modulation frequency (f), in order to obtain n demodulated signals (S(i)); determining n spectral densities (SP(i)) of the n demodulated signals (SO)); determining n characteristic frequencies (&#x3bd;) determining information on the velocity and information on the distance of the target on the basis of said n characteristic frequencies (&#x3bd;).

Method for processing a signal arising from coherent lidar and associated lidar system

A method for reducing the peak factor of a signal transmitted in a frequency band comprising several channels, the signal using a plurality of channels in the band comprises: a step of clipping the signal, a step of subtracting the clipped signal from the signal, so as to obtain a peak signal, a step of filtering the peak signal with the aid of a multichannel filter configured to comply with a predetermined spectral mask for each of the channels used by the signal, and a step of subtracting the filtered peak signal from the signal. A device for emitting a multichannel signal implementing the method for reducing the peak factor is also provided.

Method for measuring the frequency modulation of a laser source

A method for generating M demodulation signals is disclosed. In one aspect, the method includes: providing M input signals, injecting each input signal into at least one first interferometer, and detecting M demodulation signals. The method also includes choosing M positive integers that are not all equal to zero and computing M demodulation signals. The idemodulation signal being the product of R+1 functions, Rbeing the chosen integer that corresponds to the first delay of the ifirst interferometer, and the pfunction being equal to S(t)=S(t=p&#x3c4;), where p is an integer between 0 and R, &#x3c4;is the first delay introduced by the delay line of the ifirst interferometer, and S is a transform of the signal at the output of the ifirst interferometer.

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Elancourt, France

Grégoire Pillet