Nebula Public Library

The main scope of this activity was to foster the exchange of expertise between the European Lidar Network (EARLINET) and Latin America Lidar Network (LALINET), and demonstrate the capability of joint research, setting the groundwork for GALION (The Global Atmosphere Watch Aerosol Lidar Observation Network) and future calibration/validation of ESA’s atmospheric satellite missions such as Aeolus and EarthCARE.

The development of High Altitude Pseudo-Satellites (HAPS) has reached an outstanding level of maturity, with several flight demonstrations that augur soon to have operational capabilities. ESA, aware of the synergies among satellite and HAPS services, set up the HAPPIEST study to analyse the impact of the erruption of aerostatic HAPS into the telecommunications market, currently covered by space and terrestrial networks. Furthermore, some complementary payloads can serve interesting applications such as Earth observation and navigation services.

This activity presents a Synthetic Aperture Radar (SAR) simulator designed to assess the performance of bi-static SAR missions. It is a modular software able to simulate realistic SAR data (including injection of the system non-idealities), to estimate the SAR performance at radiometric and interferometric level. In order to ensure accurate measures of the bi-static performance, it simulates raw data exploiting a time-domain approach, without assumptions on the acquisition geometry. This feature makes the simulator a useful tool for the design of new SAR missions concepts.

Shannon-Nyquist theorem rules the signal sampling stating that the signal must be sampled at a rate of at least twice the maximum frequency present in the signal to be fully reconstructed. Compressive Sensing (CS) theory affirms that a sparse signal can be efficiently reconstructed by the acquisition of a number of samples far below the minimal one dictated by Nyquist theorem, thus providing a new approach to data acquisition. CS technique is based on the concept of sparsity. The information rate of a continuous 'sparse' signal may be much smaller than suggested by its bandwidth.