Multi Phase Center Processing of Ice Sounding Radar Signals for Across Track Surface Clutter Cancellation: Comparison of Surface Clutter Cancellation Techniques and Processor Concept Description

Abstract

ESA’s POLarimetric Airborne Radar Ice Sounder demonstrator (POLARIS) - build and operated by the Technical University of Denmark (DTU) - operates at P-band and features a multi-phase-center antenna for the purpose of surface clutter suppression. The first data suitable for the development and demonstration of suitable surface clutter cancellation methods were acquired in February 2011 during the IceGrav campaign in Antarctica. The purpose of the present study is to investigate and compare different methods for POLARIS surface clutter cancellation and to implement a Software Tool to augment the along-track POLARIS processor developed by ESA, thus improving bedrock detectability. The present technical note concerns about the review of suitable clutter cancellation methods and their performance analysis in the context of the POLARIS system. It includes a sensitivity analysis for different error sources, leading to the specification of a processor concept for POLARIS data clutter cancellation. The WP activities documented in this technical note are divided into four major parts: • Literature review concerning novel developments in ice sounding radar research, in particular concerning the operation and processing of data acquired with multi-phase center antenna systems. It includes a review of technical parameters of the POLARIS system, relevant for the subsequent analysis. • Analysis of Multi-Phase-Center Antenna techniques for Clutter Cancellation. The considered methods are standard beamforming, clutter angle nulling, composite arrays as well as the optimum beamformer. • Analysis of direction-of-arrival (DOA) techniques for estimating the angular origin of clutter and bedrock signal contributions. • Proposition of a processor concept for follow-on implementation of a software-tool to be used by ESA for processing POLARIS data clutter mitigation. The technical note is concluded with propositions for alternative sensor configurations, which would improve the performance of all of the analysed clutter suppression methods.