Precise orbit determination method for BeiDou mixed constellations with layered constraints
FANG Yanan, ZHU Jun, LI Jie, WANG Chong, WANG Jiasong, ZHANG Shaoyu
Acta Geodaetica et Cartographica Sinica . 2021, (4): 466 -474 .  DOI: 10.11947/j.AGCS.2021.20200406