Research And Realization Of Unambiguous Acquisition Technology Under New Signal BOC System

With the development of satellite systems in various countries,spectrum is crowded and band resources are tight.In order to alleviate the problem of resource shortage and meet the needs of high-precision positioning,BOC(Binary Offset Carrier)modulation method came into being.BOC modulation can split the spectrum of the signal on both sides of the center frequency,thereby expanding the band resources.Compared with the correlation peak of the C/A sequence in the traditional navigation signal,the maximum distance of the correlation main peak of the BOC modulation sequence is half of it,which provides a powerful premise for the receiver to achieve high-precision positioning.However,there are multiple side peaks in the correlation function of the BOC modulation sequence,which is prone to false acquisition during the acquisition process.In 2006,N.Martin proposed the BPSK-like processing method,which successfully eliminated the edge peak of the autocorrelation function,but this method uses a large number of filters and consumes more hardware resources.The ASPeCT(auto-correlation side-peak cancellation technique)method proposed by O.Julien in 2007 achieved the purpose of weakening the side peaks,but this method has the disadvantage that the side peaks cannot be completely eliminated,and can only be applied to the BOC(n,n)group.signal.In view of the shortcomings that can not eliminate side peaks at the same time and reduce resource consumption,two unambiguous acquisition algorithms are proposed.The specific work is as follows:1.A proposed based on correlation-shift unambiguity acquisition algorithm can completely eliminate the peaks during the acquisition process while preserving the narrow correlation of the main peaks.Compared with ASPeCT and BPSK-LIKE two typical acquisition methods,the computational complexity based on the correlation shift unambiguity acquisition algorithm is 62% of the ASPeCT method;it is 10% higher than the ASPeCT method in terms of peak-to-average ratio,which is 200% higher than the BPSK-LIKE method;In terms of detection probability,it is the same as the ASPeCT method,but compared with the BPSK-LIKE method,the detection probability is 2 dB higher,and the acquisition performance is excellent.2.A BOC(n,n)signal matching filtering unambiguity acquisition algorithm is proposed,which can also completely eliminate the side peaks while retaining the narrow correlation of the main peaks.Comparing the typical acquisition methods of ASPeCT and BPSK-LIKE,the computational complexity of the unambiguity acquisition algorithm of the front-rear phase correlation sub-peak elimination technique is the same as that of the ASPeCT method;the peak-to-average ratio is 10% higher than the ASPeCT method,and 200% higher than the BPSK-LIKE method.The detection probability is better than the ASPeCT method 2dBHz,and it is better than the BPSK-LIKE method 3dBHz,and the acquisition performance is excellent.3.The FPGA hardware resources are designed to implement the proposed matched filter acquisition algorithm.The system structure,pseudo-random sequence generation module,sub-carrier generation module,carrier generation module,search module and correlation accumulation module are designed and simulated.Use Modelsim software simulation to verify that the logic of each component module is correct.Experiments show that the algorithm can successfully capture the navigation signal,which is the same as the preset data parameters.