Thales

Gregory Baral-Baron

Xavier Lacondemine

Jean-Pierre Schlotterbeck

Nicolas Martin

Philippe Rondeau

Gilles Fleury

Elisabeth Lahalle

The invention relates to the measurement of the speed of an aircraft by Doppler laser anemometry, the aircraft being equipped with a LiDAR using coherent detection. According to the invention, the measurement method comprises the following steps:

Method and device for measuring the speed of an aircraft by Doppler

An anemometry system comprising a laser source supplying an incident beam that is backscattered by passing through the incident beam mixing means for mixing the backscattered beam and a reference beam, creating an interferometry wave conversion means, converting the interferometry wave into an electrical signal proportional to the power of said wave first determination means, for determining a time-frequency diagram of said electrical signal. The system also comprises second determination means for determining spots of said diagram, each spot being a set of connected points of said diagram, having exceeded a detection threshold computation means for computing an average of the frequency, a duration and a slope characterizing the trend of the frequency as a function of time in the time-frequency diagram, and determination meansfor determining the air speed from all or part of said averages of the frequency, said durations and said slopes.

Laser anemometry system and method

A method for estimating the transverse component Vof the velocity of the air comprises the following steps: emitting a focused laser beam; acquiring an electrical signal resulting from the transit of a particle across the beam at a point of transit; analyzing the signal so as to obtain a spectrogram revealing an elongate mark representative of the transit; estimating the duration of traversal of the laser beam by the particle and the slope of the mark; deducing from the duration and from the slope the distance between the point of traversal of the beam and the focusing point; determining the radius of the beam at the point of transit; deducing the transverse component from the radius and from the duration.

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Seyssins, France

Gregory Baral-Baron