The research progress of two way time synchronization with fiber based on spread spectrum signal

High-precision time synchronization is a basic element in some areas of aeronautical engineering, such as satellite navigation and deep space exploration. It is more accurate and stable to use the optical fibers while performing time frequency transfer than using other media such as GNSS common view and two-way satellite time frequency transfer. The frequency transfer is the main focus of the current research in optical fiber time frequency transfer. However, there is little study on time transfer, and the accuracy of time transfer is commonly in nanosecond level. In this paper, a two way time transfer method based on spread spectrum ranging is studied. For the proposed method, the accuracy is improved and extra links for data check are not needed any more. The designing schemes and the implementation progress of the engineering prototype are presented. The experimental results indicate that the time synchronization uncertainty is less than 30ps by use of the proposed method when the optical fiber transmission distance is within 2km.