Direction-of-Arrival Estimation Methods in Interferometric Echo Sounding

Abstract

Nowadays, there are two leading sea sounding technologies: the multibeam echo sounder and the multiphase echo sounder (also known as phase-difference side scan sonar or bathymetric side scan sonar). Both solutions have their advantages and disadvantages, and they can be perceived as complementary to each other. The article reviews the development of interferometric echo sounding array configurations and the various methods applied to determine the direction-of-arrival. “Interferometric echo sounder” is a broad term, applied to various devices that primarily utilize phase difference measurements to estimate the direction-of-arrival. The article focuses on modifications to the interferometric sonar array that have led to the state-of-the-art multiphase echo sounder. The main algorithms for classical and modern interferometric echo sounder direction-of-arrival estimation are also outlined. The accuracy of direction-of-arrival estimation methods is dependent on the configuration of the array and external and internal noise sources. The main sources of errors, which influence the accuracy of the phase difference measurements, are also briefly characterized. The article ends with a review of the current research into improvements in the accuracy of interferometric echo sounding and the application of the principle of interferometric in other devices.

A High–Efficiency Side–Scan Sonar Simulator for High–Speed Seabed Mapping

“…Moreover, the incident angle of the acoustic ray can be expressed as where is the depth of the scattering point . Similarly, direction of angle (DOA) [ 31 ] between the acoustic ray and the sensor can be expressed as …”

Assessing the Performance of the Phase Difference Bathymetric Sonar Depth Uncertainty Prediction Model

“…To address the phase ambiguity problem, occurring as soon as δL (commonly referred to as the baseline length in interferometry) is larger than λ 2 , a number of approaches exist [20,21]. The widely used method for solving the phase ambiguity is the Vernier method [15,22]. The Vernier method does not require extra equipment or hardware change.…”

“…Reference [14] discusses the influence of the phase difference estimation uncertainties using a theoretical physic based framework of the backscattered signals. Different uncertainty sources inherent to the backscattered signal structure are considered and the performance of the developed model is assessed using various numerical simulations scenarios, see also [15] for quantification of the contribution of different sources. Reference [16] quantified the uncertainties discussed in [14] for the Bathyswath-2 system (manufactured by ITER Sytems) [17] which is a phase differencing system and addressed the effect of varying transmitted pulse length on the bathymetric uncertainties.…”

Refinement of Direction of Arrival Estimators by Majorization-Minimization Optimization on the Array Manifold

“…The focus of this paper is on acoustic sound source localization, where sensors are microphones [2]. However, we note that DOA estimation is also widely applied in radar [3] and sonar [4] technologies.…”