ehl logo Acoustics & Environmental hydroacoustics Lab

Laboratories of Image, Signal processing and Acoustics - Ecole polytechnique de Bruxelles /Faculté des Sciences

Acoustic interferometry

Interferometry is an important probing technique in synthetic aperture radar (SAR) for geodesy and remote sensing applications. It measures the differences between complex-valued SAR images to infer several geophysical quantities such as topography, deformations (volcanoes, earthquakes, and ice fields), glacier flows, etc. Here, interferometry is applied as an acoustic inversion technique for ocean environment parameters (water column and bottom). The broadband sound field distribution generated by a passing ship usually exhibits interference structure. The difference measurement between measured and predicted interference images is the key procedure for passive acoustic interferometry. Many striations are visible in these images, whose slopes and positions are determined by the environment. The current research is on the striation processing for feature extraction and difference measurement. The relationship between the striation behavior and the environmental parameter variations is analyzed and processed for further environment inversion. Vector sensors have advantages in providing the particle velocity of the sound field and higher signal-to-noise ratio than scalar hydrophones. The broadband vector field also exhibits interference structures, and the difference between the broadband vector field and pressure field is closely related to environment properties. The possibility of exploiting vector sensor data in passive acoustic interferometry is also studied.