Analysis and Results of the TOPSAR Experiments in Southern Italy

This paper presents the analysis of the C-band cross-track interferometric data (XTI) acquired during the MAC Europe 1991 Campaign over the Matera test site (Southern Italy). Passive and active calibrators were deployes over a homogeneous background, and a ground truth data collection capmaign was carried out simultaneous with the flight. Tha raw data, gathered by the TOPSAR instrument on-board the NASA/JPL DC-8 aircraft, have been compressed with a range-Doppler SAR processor which takes range migration and antenna squint into account. The resulting interferogram has been obtained after co-registration performed by using 1D cross-correlation techniques. The airplane attitude angles, recorded by the navigation system, have been used to derive the baseline time variation, necessary for the 2-pi phase wrapping procedure. Assuming unperturbed aircraft translational motion, the +/- 0.2 mm accuracy on the estimate of the baseline components gave a theoretical rms error on the estimate of the height of each imaged pixel of +/- 2.5 m for extended targets and +/- 4.5 m for extended targets. Finally, the computed terrain eevation has been compared with the 1:25,000 scale digitised contour levels of the Istituto Geografico Militare Italiano (IGMI), in order to assess the height accuracy of the system. The root-mean-square errors on the height estimate have been found to be +/- 15 m for point targets and +/- 8 m for extended targets.