Space-Time Adaptive Matched-Field Processing (STAMP)

摘要

Space-time adaptive processing (STAP) is two-dimensional adaptive filter employed for the purpose of clutter cancellation to enable the detection of moving targets. It has been a major focus of research activity in radar applications for which the platform is in motion (e.g., airborne or space-based systems). In this setting, an antenna sensor array provides spatial discrimination, while a series of time returns or pulses form a synthetic array that provide Doppler (velocity) discrimination. The application of STAP for the mobile towed-array sonar system is non-trivial because of the complex multipaths in the underwater environment. On the other hand, Matched-field processing (MFP) that uses a propagation code to predict the complex multipath structure and coherently combines it to provide range/depth discrimination has been studied and demonstrated. MFP with a synthetic array (a series of snapshots) to estimate the source velocity and localize source in range and depth also has been demonstrated. STAMP combines the adjacent-filter beam space post-Doppler STAP and MFP to provide improved performance for the mobile multi-line-towed-array sonar applications. The processing scheme includes transforming phone time snapshots into frequency domain, at each frequency bin forming horizontal beams in the directions of interest for each towed line, then combining signals from multi-towed lines and adjacent Doppler bins and beams that cover the multi-path Doppler spread due to motion using adaptive MFP. A study of STAMP performance in the towed-array forward-looking problem is discussed. In this problem, the own- ship signal and its bottom-scattered energy can be treated as stationary interference with a moving target at constant speed within processing interval of a few minutes. (9 figures, 3 refs.).