| With the rapid development of technologies such as communication,positioning and navigation,and timing,more and more fields have put forward higher requirements for high-precision time synchronization technology.At the same time,the popularization and application of the global satellite navigation system has enabled the satellite-based two-way time synchronization technology to obtain good time accuracy.The accuracy is reduced and the requirements cannot be met.Therefore,it is considered that two-way time synchronization is directly performed between terminals,and the time synchronization process is completed by mutual transmission and reception of signals between the two terminals without the aid of a satellite navigation system.In the process of time synchronization,the accurate estimation of the arrival time of the signal is one of the important factors affecting the performance of time synchronization.Because the signal propagates at a low altitude,the multipath caused by the uncertainty of the path may cause the correlation peak to be unsymmetrical.The maximum value of the correlation peak cannot be estimated accurately.Aiming at this problem,a high-precision time-of-arrival estimation algorithm is proposed.phase difference,improving the accuracy of the time of arrival estimation.At the same time,the proposed two-way wireless time synchronization method is simulated and verified based on the hardware FPGA platform,and the data acquisition of the time synchronization signal is carried out in combination with FPGA+AD9361.The collected data are processed in matlab and the performance of the designed bidirectional time synchronization method is analyzed.This paper conducts in-depth research on the bidirectional time synchronization method based on pseudocode,mainly including the following research contents and work:1.First,the principle of two-way time synchronization is introduced.When the traditional time synchronization between two nodes is performed,the signal arrives at the node after processing and then returns.At this time,the channel between the two nodes may have changed,resulting in a change in the propagation delay.Subsequent time synchronization performance is degraded.A two-way time synchronization scheme is designed in view of the influence of this channel change.When the synchronization technology designed in this paper is sending signals,the master and slave nodes synchronize the reception and arrival time calculation of the signal,and consider the channel’s time in the two-way time transfer process.Symmetry can reduce the influence of errors caused by channel changes and improve the accuracy of two-way time synchronization.2.An accurate estimation method of arrival time stamp is proposed.High-precision arrival time estimation is the key technology and basis for realizing two-way time comparison.In this paper,the estimation method of arrival time is carried out in the process of signal reception and calculation.Improvement.Compared with the traditional time stamp estimation method,this method improves the phase detection method based on the principle of the phase detector,makes full use of the correlation points near the entire correlation peak,and ensures the accuracy of the time of arrival estimation by sacrificing the cost of computation.Accuracy.The complete bidirectional time synchronization process is realized by matlab simulation and its performance is estimated,and its time precision reaches sub-nanosecond level.The hardware verification of the proposed two-way wireless time synchronization technology is carried out.Based on the theoretical research,the functions of each module in the twoway time synchronization process are simulated and realized on FPGA+AD9361,and the time synchronization results are analyzed. |
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