Precise Timing Analysis Based On BDS-3 New Signals

Global Navigation Satellite System（GNSS）not only provides positioning and navigation services,but also timing and time synchronization services,which play an important role in the national economy and people’s livelihood.With the development of science and technology and social economy,the new generation of mobile communication,deformation monitoring,indoor positioning,distributed observation network,etc.all put forward the demand for time synchronization with nanosecond level or even higher accuracy.BDS-3 was officially opened.The new system signals B1C and B2a are the main signals of BDS-3.Carrying out precision timing analysis based on B1C and B2a is of great significance to promote the application of Bei Dou-3 in the field of time and frequency.The main research of this thesis is as follows:（1）The research background and current status of GNSS precision timing are briefly introduced.Several organizations involved in the experiments of this paper are described,and the Precision Point Positioning（PPP）time transfer and Real-Time Kinematic（RTK）timing techniques used in this paper are briefly outlined.（2）Analyze the performance of B1C/B2a post PPP time transfer of BDS-3 new signals.Firstly,we analyze the impact of B1C/B2a without ionospheric combined DCB correction by precision clock difference products;Secondly,we conduct post PPP time transfer tests based on three precision products,GBM,WUM and ISC,and compare them with BDS-3 B1I/B3I and GPS L1/L2 to analyze the PPP time transfer performance based on BDS-3 B1C/B2a;The GPS L1/L2 post PPP time transfer results were used as reference values for external conformity to evaluate the accuracy of B1C/B2a post PPP time transfer.The results show that for the three domestic time links,B1C/B2a PPP time transfer accuracy is better than B1I/B3I;for the two foreign time links,B1I/B3I PPP time transfer accuracy is better than B1C/B2a.B1C/B2a PPP time transfer accuracy of GBM product is optimal,better than 0.39 ns.WUM product B1C/B2a PPP time transfer accuracy is slightly worse,the accuracy is better than 0.40ns.ISC product B1C/B2a PPP time transfer accuracy is the worst,but still better than 0.50ns.（3）Analyze the real-time PPP time transfer performance of B1C/B2a signals in the new BDS-3 system.Firstly,real-time PPP time transfer experiments are carried out based on CNES products,and the performance of B1C/B2a real-time PPP time transfer is analyzed by comparing with BDS-3 B1I/B3I and GPS L1/L2.The L1/L2 real-time PPP time transfer results based on CNES products are used as reference values for external conformity to evaluate the accuracy of B1C/B2a real-time PPP time transfer.Next,an imitation real-time experiment based on the i GMAS ultra-fast product ISU product was conducted to analyze the time transfer accuracy of B1C/B2a signals when using the ISU product.The results of BDS-3 B1C/B2a real-time PPP time transfer based on CNES product are less accurate compared with B1I/B3I,but its accuracy can still be better than0.71ns;although ISU is a forecast product,the accuracy of BDS-3 B1C/B2a imitation real-time PPP time transfer based on ISU product can still reach 1.26ns.（4）Analyze the performance of RTK timing based on BDS-3 new signal B1C,B2a.The RTK timing performance of B1C and B2a signals is compared and analyzed comprehensively by performing single and dual frequency RTK timing solutions for BDS-3 B1C and B2a,BDS-3 B1I and B3I and GPS L1 and L2 in Kinematic,Static and Fixed modes respectively.The results of GPS L1/L2 post PPP time transfer and two-way optical fiber time and frequency transfer are used as reference values for external compliance to evaluate the RTK timing accuracy of B1C and B2a.The test results show that the RTK timing accuracy of BDS-3 B1C and B2a is comparable to that of GPS L1 and L2,and better than that of BDS-3 transition signals B1I and B3I;the RTK timing accuracy of common clock zero baseline,common clock ultra-short baseline,non-common clock ultra-short baseline and short baseline B1C is better than 0.015ns,0.09ns,0.22ns and 0.58ns,respectively B1C/B2a timing accuracy better than 0.027ns,0.36ns,0.26ns,0.31ns,respectively;compared with two-way optical fiber time and frequency transfer,B1C RTK timing accuracy better than 0.51ns,B1C/B2a timing accuracy better than 0.17ns;The10000-second stability of zero baseline can enter the10^-16magnitude,the 10000-second stability of ultra short baseline can enter the10^-15magnitude,the 10000-second stability of short baseline B1C single frequency can enter the10^-14magnitude,and the 10000-second stability of B1C/B2a dual frequency static and fixed station modes can enter the10^-15magnitude.