The High Dynamic Acquisition And Tracking Algorithm On A Newly Modulated GNSS Signal

For over half a century,with the rapid development of aerospace industry,satellite navigation technology has made a spurt of progress and has profoundly changed our way of life and battle tactics in modern war,furthermore,new technologies and algorithms are still emerging.The proposed of binary offset carrier modulation(BOC)has greatly improved the spectrum utilization rate of the navigation signals and alleviated the lack of the frequency band resources.However,the multi-peak problem caused by BOC modulation brings severe difficulties to its acquisition and tracking algorithm.In order to solve this problem,the frequency chirp BOC(FC-BOC)signal and frequency hop BOC(FC-BOC)signal are proposed in this paper.These two signals' correlation functions are presented as combining multiple BOC signals correlation function together,which can reduce the secondary peaks of correlation function by changing the subcarrier frequency.They could improve the positioning accuracy of the navigation system,for these two new modulation signals have sharp and likely single peak correlation functions,at the same time,the anti-interference and stealth property would be enhanced as well.Based on the comparison between traditional BOC signal and the new modulation signal from correlation function and power spectral density,this paper selects the partial matched filter and fast Fourier transform algorithm to acquire FC-BOC signal and FH-BOC signal.Aided by inertial navigation system(INS),which provides the velocity and the acceleration information,this algorithm improves the acquisition speed and accuracy,and it is referred to as INS/PMF-FFT algorithm in this paper.The carrier tracking loop uses the structure of second order FLL assisting third order PLL to accomplish accurate tracking.As for the PRN code loop and the subcarrier loop,coherent tracking is selected to reduce the influence of dynamic stress by utilizing doppler frequency shift information from carrier tracking loop,and also uses the help of INS to improve tracking precision and stability.Finally,a large number of simulations are given to reaserch the acquisition and tracking performance of the new modulation signal.Judging from the simulation results,it can be obtained that,the INS/PMF-FFT algorithm for the FC-BOC signal and FH-BOC signal acquisition are faster with higher accuracy than the traditional BOC signal,and would hardly be affected by multi-peak problems,moreover,INS aided coherent tracking algorithm can quickly get into lock and keep tracking the FC-BOC signal and FH-BOC signal stably.