The Application Of The Drift Scanning Technology To CAPS Orbit Determination

China Area Positioning System (CAPS) is a satellite navigation system de-veloped independently by our country which uses the commercial geosynchronoussatellites to constitute the basic constellation.The navigation signals are gener-ated by the ground system and the goals of high positioning precision and timeservice by the transmitting mode are realized. The precise orbit measurement anddetermination of the GEO satellite is a key in this system,whose precision directlya?ects the accuracy of the navigation and positioning of its users. Ground-basedoptical observation plays an important role in the positioning determination ofthe geosynchronous orbit satellite , which can provide angle measurement dataand it's also a constraint to the ranging data.Some possibilities to realize thecombining orbit determination are researched.With a small aperture optical telescope , a drift-scanning camera and re-lated hardwares and softwares ,a set of GEO satellite optical angle measuringsystem was built up . The structure of this system is described in this paper, and the problems encountered during the phases of commission and the trialobservation were debated .With the drift scanning mode and staring mode to thebackground stars and GEO satellites in the optical observations , a large numberof observations were obtained , which makes the optical observation of satellitesmore convenient and faster . After introducing the drift scanning technology , itnot only greatly increases the observation data's quantity, but also improves theaccuracy of observation position . By analyzing the trial observation data , theinternally coincident precision and external coincident precision with the pseudocode ranging system were given , and ultimately the goal of the combining or-bit determination between the GEO satellite optical angle measuring system andthe pseudo code ranging system was achieved . View the result of observationdata analysis , the accuracy of this angular data is higher than the existing anglemeasurement technology an order of magnitude .The preliminary analysis's result shows that the current accuracy of the GEOsatellite optical angle measuring system is better than 0.5 arcsecond , which canprovide the necessary support for the high precise orbit determination of the Chi- nese Area Positioning System.