Research On Acquisition And Tracking Method Of Navigation Signal Based On BOC Modulation

As a new modulation method,BOC modulation technology is widely used in global satellite navigation systems.It can avoid spectral aliasing with other signals in terms of spectrum splitting characteristics and narrow correlation peak characteristics,and enhance anti-multipath capability and pseudo-code tracking accuracy.Under the condition of limited frequency band resources,the problem of compatibility and coexistence of satellite navigation systems such as GPS,Galileo,GLONASS,and Beidou is well solved.However,the autocorrelation function of the BOC signal has multiple secondary peaks compared to the traditional BPSK signal.When the GNSS receiver performs capture and tracking processing at the receiver,it is easy to capture other side peaks,which will cause ambiguity.This subject is aimed at the research of the above-mentioned problems based on BOC modulation without blur acquisition and tracking.The main research contents are summarized as follows:Firstly,this paper studies the satellite signal modulation technology,including traditional BPSK modulation,standard BOC modulation,and derived MBOC and Alt BOC modulation techniques.It focuses on the detailed BOC modulation principle and simulates the spectral density and autocorrelation function of BOC signals.Secondly,three classic BOC ambiguity-free acquisition algorithms are introduced:BPSK-like,SCPC,and ASPe CT.The principles of the three algorithms are specifically introduced,and the advantages and disadvantages of the three algorithms are verified through theory and simulation.An unambiguous acquisition algorithm for BOC(n,n)signal based on the combined correlation function is proposed in this paper.Simulation results show that the detection sensitivity of the sub-correlation function method is improved by3 d BHz compared with the classic ASPe CT algorithm for BOCs(1,1)signals.the detection probability is similar to the BPSK-like method for BOCc(1,1)signals.In addition,a acquisition algorithm based on correlation shift is proposed.Compared with BPSK-like and SCPC algorithms,this method has higher deblurring effectiveness and capture sensitivity.Finally,the tracking principle of satellite signals and the traditional GPS tracking loop are described.This paper proposes a new fuzzy-free tracking algorithm,which combines the reconstruction rules into a new correlation function to complete the tracking of BOC(n,n)signals.It keeps the narrow correlation and eliminates the secondary peak.The advantage of this algorithm is that it is easy to operate and does not need to design auxiliary signals.It only needs to perform auto-correlation processing for BOC(n,n)signal,which will make its implementation complexity lower.The theoretical derivation and simulation analysis results show that: compared with the traditional EMLP,ASPe CT and SCPC algorithms,the main peak of the algorithm is sharper and higher,and the deblurring performance is the best.The phase-detection curve has a larger slope in the linear interval of-0.1Tc 0.1Tc,which is more stable.For BOC-sin(n,n)and BOC-cos(n,n)signals,compared with the SCPC algorithm,the mean square error of the code phase measurement error is reduced by 0.36 Tc and 0.31 Tc,respectively,and the anti-noise performance is the best.The multipath envelope area is the smallest and the multipath suppression effect is the best in terms of anti-multipath performance.