The Impact Of Non-ideal Channel On BOC Tracking Performance

To achieve the spectrum separation of military and civilian signal and improve the performance of the navigation system,the world’s major satellite navigation systems have begun the process of modernization and BOC modulated signals have been widely used.Compared to the traditional BPSK modulated signal,BOC signals have a broader bandwidth and multi-peaks,which are more vulnerable to the impact of non-ideal channel.This paper studies the tracking performance of BPSK-Like algorithm as well as Double Estimate algorithm,which are representative and widely used in in the current project under non-ideal channel.Concentrated on this,the study of this paper contains the following aspects:First,the paper studies the tracking performance of BPSK-Like algorithm under non-ideal channel.It begins with the dual sideband model of BOC signal and analysis the Impact of bandwidth on tracking performance.It points out that when the bandwidth is larger than the mainlobe of BOC signal,the correlation function would have deformation.The paper also gives where the deformation position and how to choose a proper early-late space in order to avoid the possible deterioration in performance.Moreover,the paper make a theoretical analysis of the tracking accuracy and tracking bias,and testify the correctness of the theoretical analysis through simulation.Second,the paper studies the tracking performance of Double Estimator algorithm under non-ideal channel.Because of the complex form of the two-dimensional cross-correlation function of the BOC signal,few articles studies the performance of DET algorithm.This paper describes the basic principles of the algorithm and points out that there No longer exists specific relationship between code tracking result and subcarrier tracking result under non-ideal channel.This paper based on the fact that the non-ideal has different influences on code loop and sub-carrier loop,so we can estimate tracking bias of subcarrier loop around zero firstly and then use the one--dimensional conditional cross correlation function to estimate the tracking bias of code loop.At last,it use simulation to testify the correctness of the theoretical analysis.Third,in order to solve the Fluctuation problem of DET algorithm,the paper start with the respect of the difference output of DLL before and after jump of DET results and put forward two improved algorithms,At last,it gives the applicable conditions and the advantages and disadvantages of the improved algorithms.