A procedure to recover data of a cubesat mission at very low S/N ratio

Abstract

This paper deals with the activities led in the framework of E-ST@R-II cubesat mission to decode the downlink telemetry signal, which was affected since launch by a power drop in the order of 20dB with respect to the computed link budget. Despite optimization of the ground station, with installation of higher gain antennas and more performant low noise amplifiers, it was not always possible to directly decode the received signal using existing modems, either hardware or software based. Therefore, a dedicated signal demodulation algorithm was developed and used to post-process all recorded data since launch. The algorithm has been verified and optimized by checking its performance against test data and then it was used to extract useful information from recorded satellite telemetry.