Reconstruction of the Radar Image From Actual DDMs Collected by TechDemoSat-1 GNSS-R Mission

In this study, a new high-level remote sensing image product is generated by exploiting Global Navigation Satellite System-Reflectometry (GNSS-R) measurements collected by the TechDemoSat-1 (TDS-1) mission. This product consists of normalized radar cross-section (NRCS) measurements arranged in a gridded format. The product is obtained reconstructing NRCSs from actual TDS-1 delay Doppler maps (DDMs) using a deconvolution method based on the two-dimensional (2-D) truncated singular-value decomposition (TSVD). The proposed method is here tested, for the first time, on actual DDMs that include nonhomogeneous areas related to land/sea transition. Experimental results demonstrate that: 1) the gridded product can be successfully reconstructed from actual DDMs; 2) this product is suitable for imaging remote sensing purposes since it exhibits a uniform spatial resolution of 8 × 30 km within an area of around 40 × 40 km; 3) land/sea transitions, which can be hardly recognized in the DDM, can be well located in the gridded product.