ApRES: Autonomous phase-sensitive FMCW radar, for basal monitoring and imaging of antarctic ice shelves

A ground-based phase-sensitive FMCW radar system, and associated signal processing algorithms, have been developed at UCL for millimetre-precision monitoring of Antarctic ice shelf thickness to derive basal melt rates [1]. To support the practical realisation of this radar, and to confirm that suitable performance is obtained, rigorous bench testing have been performed. These tests were conducted on the prototype radar system using coaxial cables in the laboratory at room temperature and to -15°C. Since 2011, the radar system has successfully acquired sounding data from various field locations in Antarctica. The phase-sensitive radio echo sounding (pRES) technique was originally demonstrated by scientists at the British Antarctic Survey for monitoring ice-shelf melt rates, requiring millimetre-precision range measurements [3]. pRES is a stepped-frequency radar implemented using a commercial, laboratory-grade, vector network analyzer. However, it has drawbacks such as high power consumption (1kW petrol generator needed), low portability, high noise figure, and therefore the measurement datasets are limited in length because the instrument cannot be left unattended. This presentation describes our custom-designed radar instrument, based on a novel phase-sensitive FMCW technique [1] and low-cost antenna arrays, which has been developed to enable year-round monitoring and imaging of ice-shelves.