Motion compensation on baseline oscillations for distributed array SAR by combining interferograms and inertial measurement

Abstract

Distributed array synthetic aperture radar (DASAR), in which multiple distributed antennas are mounted on a crosstrack, has applications that include multibaseline interferometry, multiple-input multiple-output SAR, and tomography. However, this flexible imaging geometry requires accurate measurement of the movements of each antenna. High-precision navigation systems are commonly used, but configuring a separate navigational system for each antenna is challenging and costly. In this study, the authors proposed a novel motion compensation scheme for DASAR that combines inteferograms and inertial measurement. The authors fabricated a rigid baseline (RB) and multiple flexible baseline (FB) configuration, fitted with a large and accurate position and orientation system and with multiple smaller, low-precision inertial navigation systems (INS) for motion measurement. The authors introduced a new robust algorithm based on a function relating RB and FB interferometry, and used this to estimate the relative movements. Finally, a Kalman filter was designed to integrate the results of databased estimation and inertial measurement. This combined the strengths of data estimation for slow movement and inertial measurement for fast movement. The results of both simulations and airborne experiments confirmed the success of this novel approach in allowing a small INS to be used for motion compensation in DASAR applications.