Acta Geodaetica et Cartographica Sinica ›› 2019, Vol. 48 ›› Issue (2): 198-206.doi: 10.11947/j.AGCS.2019.20170701

• Geodesy and Navigation • Previous Articles     Next Articles

Orbital elements ephemerides and interfaces design of LEO satellites

FANG Shanchuan1, DU Lan2, GAO Yunpeng2, ZHOU Peiyuan2, LIU Zejun2   

  1. 1. Technical Department of Taiyuan Satellite Launch Center, Taiyuan 030027, China;
    2. Information Engineering University, Zhengzhou 450001, China
  • Received:2017-12-08 Revised:2018-06-18 Online:2019-02-20 Published:2019-03-02
  • Supported by:

    The National Natural Science Fundation of China (Nos. 41774038;41804034);The Fund of the State Key Laboratory of Geo-Information Engineering Laboratory (No. SKLGIE2016-Z-2-4);The Open Project of Shanghai Key Laboratory of Space Navigation and Positioning Techniques Fund (No. KFKT_201707)

Abstract:

Low earth orbit satellites, with unique advantages, are prosperous types of navigation augmentation satellites for the GNSS satellites constellations. The broadcast ephemeris element needs to be designed as an important index of the augmented LEOs. The GPS ephemerides of 16/18 elements cannot be directly applied to the LEOs because of the poor fitting accuracies in along-track positional component. Besides, the ill-conditioned problem of the normal-matrix exists in fitting algorithm due to the small eccentricity of the LEO orbits. Based on the nonsingular orbital elements, 5 sets of ephemerides with element numbers from 16 to 19 were designed respectively by adding or modifying orbital elements magnifying the along-track and radial positional components. The fitting experiments based on the LEO of 300 to 1500 km altitudes show that the fitting UREs of the proposed 16/17/18/18*/19-element ephemerides are better than 10/6/4/5/2.5 cm, respectively. According to the dynamical range of the fitting elements, the interfaces were designed for the 5 sets of ephemerides. The effects of data truncation on fitting UREs are at millimeter level. The total bits are 329/343/376/379/396, respectively. 29/15 bits are saved for the 16/17-element ephemerides compared with the GPS16 ephemeris, while 64/61/41 bits can be saved for the 18/18*/19-element ephemerides compared with the GPS18 elements ephemeris.

Key words: LEO satellites, broadcast ephemeris, nonsingular orbital elements of the first kind, quantization unit

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