Orbit determination of artificial satellites in real time using gps navigation solution / Determinação de órbitas de satélites artificiais em tempo real através da solução de navegação de GPS

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

The Global Positioning System (GPS) is a satellite navigation system that allows the users to determine 3D positioning and the time with high precision. Its main purposes are: aid to radionavigation in three dimensions with high precision positioning, navigation in real time, global coverage and quick acquisition of data sent by the GPS satellites. It is proposed, in this work, to estimate, in real time, an orbital state vector composed by position, velocity, bias and drift of the GPS receiver clock on board satellites by processing the raw navigation solution obtained by the on-board receiver. In this work the Kalman filter is used to estimate the state vector based on the incoming observations from the receiver. The Kalman filter is used due to its robustness in real time applications, without unnecessary storage of observations, as they can be processed while being collected. The filter dynamic model includes perturbation due to geopotential and the observations are the raw navigation solution composed of position and receiver clock bias. The velocity components of the navigation solution are not used due to its low accuracy. Simulations and tests are done using real data from TOPEX/POSEIDON satellite and comprising three days of observations. A comparison is done between the estimated state vector and the precise orbit ephemeris (POE) produced by JPL/NASA. The proposed procedure performance and characteristics are analyzed, including effects of the dynamic model, step-size of integration and SA (Selective Availability) effect, to show the impact on the procedure in terms of global accuracy obtained.

ASSUNTO(S)

filtro de kalman órbita satélites artificiais global positioning system orbits space technology and engineering kalman filters modelo dinâmico sistema de posicionamento global engenharia e tecnologia espacial artificial satellites dynamic model

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