Abstract: In order to solve the problems of the decrease in accuracy of GPS Common View(CV) time comparison with the increase of baseline and the inability to perform common-view time comparison in case of very long baselines,the linearization property of the satellite-ground clock differences based on the international standard GNSS common-view files is used to calculate the interpolation results,which increases the number of available satellites.Finally,the CV results of different satellites are weighted to improve the performance of GPS CV in case of long baselines and to reduce baselines length constraint on CV.The one-month satellite-ground clock differences from three timekeeping laboratories,National Time Service Center(NTSC),Korea Research Institute of Metrology and Science(KRISS),and Physikalisch-Technische Bundesanstalt(PTB),are selected as the data samples,and the satellite-ground clock differences of individual satellite are linearly interpolated with a time interval of 300 s,then the time comparison results of all the satellites at the same time are weighted equally to obtain the final results.The results show that the Root Mean Square(RMS) of time difference between the linear interpolation CV results and the GPS PPP results on NTSC-PTB and KRISS-PTB links are 0.53 ns and 0.8 ns,respectively,which are improved by 48% and 54% compared to the traditional CV.

Key words: Linear interpolation, Satellite-ground clock differences, Common-view time comparison, Time comparison accuracy