Research On Acquisition Of Navigation Signals Based On BOC Modulation

Binary Offset Carrier(BOC)modulation is an essential technique in the future satellite navigation system,European Commission and United States and Chinese Compass had decided to implement the BOC in the future.BOC modulation has been applied widely,and its technology has attracted the attention of the majority of the scholars in the world.The main works are summarized as follows:In this article,it has carried on the detailed analysis to the Binary Offset Carrier modulation signal characteristic.By analyzing the signal power spectral density function knows the spectrum of signal is split.This signal by the correlation function of the signal analysis shows a narrow correlation peak associated with a high tracking accuracy potential.At the same time,BOC modulation signal and BPSK modulation signal for making comparison analysis on each aspect,reflecting the superiority of BOC modulation on the signal characteristics.Then,this paper analyzes the acquisition techniques used by satellite signal receiver.In the signal acquisition process,common ways of acquisition are discussed.Because BOC(15,2.5)modulation signal is adopted by the BeiDou Navigation Satellite System B3 spectrum signal,also this signal has ambiguity problem.Ambiguity is one important factor affecting the acquisition accuracy,in order to alleviated the impact of ambiguity for BOC(15,2.5)signal,new correlation functions are proposed.The new methods are implemented to create a no-side-peak combined correlation function by designing the modulated symbols of one local signal,it then pluses to the BOC autocorrelation function.Simulation results show the technique can completely eliminate the side-peaks of BOC(15,2.5)signal and achieve unambiguous BOC(15,2.5)signal acquiring.For the sake of acquisition techniques of the binary offset carrier modulation signal in weak S/N condition,the technique of how to implement fast integration SNR gain and the binary offset carrier signal acquisition method are research in the article.Several main factors need to be taken into consideration while acquiring weak signal.The main method to enhance the satellite navigation signal to noise ratio is cumulative gain algorithm,in this paper,it start the research based on the traditional signal to noise ratio accumulation algorithm,and comprehensive analysis of the various cumulative advantages and limitations of existing algorithms,the differential coherent integration is most suited for weak signal acquisition.On the basis of coherent integration algorithm and differential coherent integration algorithm combined,to modify the part of coherent integration,and propose a new method of the overlap difference cycle coherent integration.Due to the characteristics of the binary offset carrier modulated signal and the weak signal,the paper use this new method and autocorrelation side peaks cancellation algorithm combines to form a specialized BOC signal acquisition method is suitable for weak signal.Simulation results shows that for low signal-to-noise ratio of BOC modulation signal,new proposed method has excellent detection performance.In the final part of the article,summarizes the content of the research and point out future research direction.