Study On Synchronization Method Of TDDM-BOC Signal In GNSS

GNSS is compose of the America's GPS,Russia's GLONASS,Europe's Galileo and Chain's Compass,etc,GNSS is one of the most rapid development of information technology at present,With the rapid development of GNSS,the TDDM-BOC(Time Division Data Modulation-Binary Offset Carrier)modulation technique effectively solved the problem of band crowded.Compared with the PSK(Phase Shift Keying)modulation technique,the TDDM-BOC modulation signal has the characteristics of time division data and spectrum splitting.The characteristic of time division data can improve the security and anti-performance of the navigation signal.The characteristic of spectrum splitting can reduce the performance between signals.For GNSS,the signal synchronization performance of the receiver was important.The synchronization was the precondition of the data processing.The spectrum splitting of TDDM-BOC signal has the characteristic of multimodal features on auto-correlation.Its correlation function was steeper than the traditional PSK signal,and it can improve the synchronization accuracy.But it is difficult to capture because of the multimodal.The existing TDDM-BOC signal synchronization methods are BPSK-like algorithm,ASPect algorithm,fractal reconstruction algorithm,etc.They are insufficient in the capture accuracy,applicability,and the amount of computation,etc.Therefore,the BPSK-like algorithm and ASPect algorithm are improved.The improved algorithms are proved to be effective through the simulation analysis.In the end of this paper,,a kind of auxiliary cross-correlation function is used to reconstruct the auto-correlation function of synchronization algorithm P-ACCF(Parallel auxiliary cross-correlation function).Its feasibility and validity is studied through theory and simulation.In the anti-performance ability and the synchronization efficiency,P-ACCF synchronization algorithm than the other three kinds of algorithm has better performance.That P-ACCF synchronization algorithm is more suitable of TDDM-BOC signal synchronization in GNSS.