Abstract: Short baseline precise common-view time transfer is one of the fundamental tasks in the time-frequency domain and has become a research hotspot of GNSS time-frequency. In order to improve the accuracy and reliability of short baseline precise common-view time transfer, various strategies are compared, and an optimization scheme is presented in this paper based on the results of fiber optic bidirectional time transfer experiments. Experiments are conducted, using continuous observation data from multiple tracking stations in Xi'an for multiple days. The experimental results show that it is not advisable to use any ionospheric and tropospheric correction models for ultra short baseline situations. When the baseline is long, appropriate tropospheric and ionospheric correction models must be used. The ionospheric delay modified by the ionosphere-free combination can significantly improve the accuracy of the results by up to 76.9%. The result of the accuracy improvement effect is not obvious by correcting the troposphere. The number of visible satellites can be increased by appropriately reducing the elevation mask, and the results can be improved with this method. Bidirectional filtering can improve convergence, and the time transmission precision can be improved by 40.9%. 

Key words: precise common view, time transmission, ionosphere delay, tropospheric delay, elevation mask, filter