Research On Unambiguous Acquisition Technology For BOC(m,n) Signal

The Global Navigation Satellite System(GNSS)has been of great significance and strategic value in today when the informationization is highly developed.Signal acquisition is the first step and the most important part of satellite navigation.At present,the research on satellite signal acquisition technology mainly focuses on the performance of traditional signal,such as accuracy and sensitivity,while the modern GNSS signals mostly adopts the new Binary Offset Carrier(BOC)modulation,and its correlation function has multi-peak characteristics,which leads to the problem of false capture of BOC signal.It makes the acquisition unambiguous and greatly affects the correct capture of signal.Therefore,it is of great practical significance to study the BOC signal acquisition technology.Firstly,the structure and characteristics of BOC modulated signal are analyzed and studied in this thesis.The BOC modulated signal is generated by simulation,and its modulation principle,spectrum characteristics and correlation are analyzed and studied in detail.BOC modulated signal has two advantages: first,the signal power spectrum has the splitting characteristic,which can effectively reduce the interference between signals;Second,the signal correlation function has a narrower correlation peak,which can obtain higher positioning accuracy.Secondly,for the ambiguity of BOC signal acquisition,this thesis systematically analyzes the basic principle and performance of three classical algorithms for BOC signal acquisition,multi-carrier model BPSK-Like method,ASPe CT and SCPC.On this basis,based on the idea of split reconstruction,an unambiguous acquisition algorithm based on BOC/PRN cross correlation shift multiplication and its fast algorithm for BOC(m,n)signal are proposed,and the performance of the algorithm is analyzed and verified by simulation experiments.The results show that the detection probability of the shift multiplication algorithm is about 3.5d BHz better than that of the ASPe CT method.However,the fast algorithm solves the problem that the traditional acquisition algorithm cannot simultaneously eliminate the multi-peak and retain the narrow correlation peak characteristics of BOC signal.The detection probability is about 3 d BHz better than the ASPe CT method,and the amount of computation is reduced by40%.Thirdly,aiming at the problem of high complexity and large hardware resource consumption of split and reconstruction algorithm,a non-split BOC(m,n)unambiguous acquisition algorithm based on BOC/PRN cross-correlation time-shift reconstruction was proposed.The experimental results show that the performance of the algorithm is equivalent to that of the split reconstruction algorithm in the same case,and the algorithm complexity and the hardware resources are reduced.Finally,in order to further improve the acquisition sensitivity and reduce the hardware resource consumption and algorithm complexity,a GNSS single frequency multi-code unambiguous joint acquisition algorithm based on channel fusion is proposed.Compared with the existing single frequency joint acquisition algorithm,the proposed algorithm eliminates the ambiguity of BOC signal acquisition and the multiple peaks caused by the different cycle lengths of different signal numbers,improves the acquisition performance,saves hardware resources,and is easy to be implemented in engineering.