Precise orbit determination for GPS and GLONASS satellites on the basis of IGS data

This paper considers the problem of precise orbit determination for GPS and GLONASS navigation satellites. Satellites´ position aiding information provided by the International GNSS Service (IGS) and becomes available on specialized web sites is used. The paper contains the description of algorithms that estimate the position and the relative velocity of navigation satellites and also uncontrollable external disturbances acting on them at high level of accuracy. Comparative analysis of results is adduced.