Research On National Standard Time Recurrence Method Based On Satellite All In View

Precise time transfer technology has been widely used in astronomical observation,deep space exploration,satellite navigation and other fields,in order to meet the needs of users for high-precise time,research institutes at domestic and abroad have developed various remote time transfer systems based on satellite common view(CV)and other remote time comparison technologies,typical service accuracy is within 5?10ns.According to the principle of CV,the two stations participating in the comparison can observe at least one satellite at the same time.Therefore,the accuracy and application range of the time transfer system based on the CV are limited by the length of the baseline,in response to this problem,this paper studies the method of applying all in view(AV)technology to the standard time reproduction system of National Time Service Center,expand the application scope of the standard time remote reproduction system based on CV.The main work and innovations points are summarized as follow:(1)The traditional AV has high accuracy,but due to the use of precise ephemeris products,the time comparison result is generated late,can not meet the real-time generation of time comparison results required by the standard time remote reproduction system.This article uses the predicted part of the IGU-P(Ultra-Rapid(predicted half))ultra-fast ephemeris product released by the IGS data center,and according to the characteristics of the data designed the use strategy.Analyze the combined ephemeris data,this method can obtain the orbit accuracy of 5cm and the clock error accuracy better than 1.5ns.Design experiment scheme,verify the feasibility of real-time GNSS AV comparison,compared with the AV time transfer results calculated using IGS precise ephemeris products,the deviation of the AV using IGU-P is within ±2ns,and the RMS value is 0.41 ns.(2)For limitations of existing systems,based on the original GNSS CV standard time reproduction system,a remote real-time GNSS AV comparison solution isdesigned,the cloud service data processing function is added,realize timely access to IGU-P products and save it in the specified file directory,forwarding the data files to the terminal in the form of global broadcast,directional domain broadcast and directional terminal according to the forwarding plan and strategy,support each terminal in the system to generate real-time AV time comparison results.(3)In this paper,the source of error and the type of noise AV comparison are analyzed,the method of Vondrak filtering to reduce the noise of AV time comparison is used,determination of optimal Vondrak filter factor based on observation noise error method,increased the short-term stability(within days)of the AV time transfer results by more than 5 times.(4)Apply the GNSS AV data processing algorithm software and the designed cloud service communication framework software to the standard time remote reproduction system,this method can set the observation period independently,real-time generation of time comparison results with accuracy better than 3ns,meet the needs of time comparison worldwide.