On-board axial detection of wake vortices using a 2-μm LiDAR

This paper describes the first successful attempt to detect wake vortices axially using an on-board infrared pulsed Doppler LiDAR (Light Detection And Ranging). On-board axial detection is more complex than the classic ground-based tangential approach, because the axial air speed in vortices is low and the atmospheric particle density is reduced, yielding a poorer SNR. To provide meaningful results in such unfavorable conditions we have developed a new flexible signal processing method based on a two-primitive model fitting the spectrum of the Doppler return. This new spectral estimation successfully detects wake vortices with an admissible SNR that is lower than other on-board state-of-the-art approaches. It was validated through flight tests.