Design And Realization Of Broadcast Ephemeris For The Synchronous Satellite

Broadcast ephemeris which provides navigation satellites’ position and velocity informationto the navigation users is an important component of the navigation message of navigationsatellite system. Broadcast ephemeris’s precision and stability directly determines the system’snavigation performance. Therefore, broadcast ephemeris parameters model and its application isa key technology of the navigation satellite system. With regard to the design of broadcastephemeris for the synchronous satellite navigation experimental system, the main contents of thiswork are as follows:(1) Having a research on the GPS broadcast ephemeris parameters model and theGLONASS broadcast ephemeris parameters model. The physical meaning of the parameters ofboth model of broadcast ephemeris is thorough illustrated and the calculation algorithm isshown.(2) Having an in-depth study on the construction of the synchronous satellite system.Considering the mixed constellation consists of GEO and IGSO satellites, the GPS andGLONASS broadcast ephemeris parameters model is unfit for the synchronous satellitenavigation experimental system.(3) The Chebyshev polynomial is adopted to fit the orbit of navigation satellite system. Dueto the continuous movement of navigation satellite, the orbit of navigation satellite should beexpressed in multinomial. Through the comprehensive comparison of different polynomials, wechoose Chebyshev polynomial to fit the orbit. This method bases on Cartesian coordinate systemavoiding the confusion of little inclination and little eccentricity.(4) Having a research on the fitting parameters in detail. Using the orbit provided byChinese Area Positioning System(CAPS), the experiment is carried. Lastly, we adopt thepolynomial of degree6, fitting span for30minutes, an arc overlap of15minutes and time slotfor1minutes as its broadcast ephemeris in this system. The fitting accuracy of this method isless than1cm.(5) Completion of the broadcast ephemeris generation and transmission softwaredevelopment. Through the comprehensive comparison of the above study, the design of the mainfunction module is fully illustrated from requirements analysis to logical framework. Eventually,we complete the development and testing work of the broadcast ephemeris generation andtransmission software on the Windows platform.