JIA Xiao-lin1, FENG Lai-ping1, MAO Yue1, YANG Hai-yan2

(1. Xi’an Research Institute of Surveying and Mapping, Xi’an 710054, China;

2. National Time Service Center, Chinese Academy of Sciences, Xi’an 710600, China)

Abstract:The definition and calculation methods for the frequency accuracy, stability and drift rate of GPS on-board clocks are introduced. The performance indices of GPS on-board clocks are analyzed based on the IGS （international GNSS service）precise clock data. The results based on the hadamard variance show that the stability (t =1 d) for the Rb clocks of GPS Block IIR satellites is about 1~3´10-14.

Key words: accuracy; drift rate; Hadamard variance