GMV has recently developed a new Flight Dynamics and geodesy library called FocusPOD, written in modern C++ and python from scratch. This library supports several projects led by GMV, including the operational provision of Precise Orbit Determination (POD) products of the Copernicus Sentinel satellites in the frame of the ESA Copernicus POD (CPOD) Service contract, the simulation of GNSS and SLR data for Galileo 2nd Generation (G2G) System Test Bed, or the maintenance of a catalogue of orbit debris.
With the objective to make FocusPOD a reference SW in geodesy, DORIS processing has been incorporated into the library. This contribution will describe how the DORIS observables are modelled and which parameters are estimated, using as a real showcase Sentinel-3 and -6 real DORIS observations. The achievable accuracy will be shown by comparing LEO POD orbits based on DORIS with the current state-of-the-art combined solution generated by the CPOD Service. Other processing metrics such as empirical accelerations and residuals will also be analysed. Particular attention will be paid to the treatment of the DORIS receiver clock reconstruction. In this line of investigation, the CPOD Service has proposed to provide GNSS-based receiver clock series to the IDS Working Group on Sentinel clock modelling and will also assess how the GNSS clocks fit into the DORIS processing, analysing how the different GNSS clock generation strategies impact the results.
This contribution will present the implemented DORIS processing strategy in FocusPOD, and the achievable accuracy for the Copernicus Sentinel-3 and -6 satellites. Moreover, the results of the GNSS receiver clock analysis integrated with DORIS will be shown. Next evolutions in terms of DORIS processing will be highlighted, focusing on enhancing the receiver clock treatment and also adding more geodesy capabilities to the library, like the estimation of Earth Orientation Parameters and station coordinates.