Research On The High-Sensitivity Acquisition Technology For GPS Weak Signal

With the rapid development of GPS and a continued increase in its applicationrange, high-sensitivity processing technology for GPS weak signal becomes the focus ofcurrent research. While the acquisition of the weak signal is the basis and key part of theprocessing technology, and the performance of the traditional acquisition algorithms forweak signal is poor. So, the high-sensitivity processing technology for GPS weak signalis investigated in this paper. Because of the resemblance of different navigation systems,the research of this paper can be modified to fit any other GPS signal or othernavigation systems, such as Galileo or CNSS. So this work has realistic meaning andcharacters of generality.Firstly, traits of GPS L1signal are introduced in this paper, meanwhile, thedefinition of the GPS weak signal and the acquisition principle of the GPS signal aredescribed. Then the coherent integration algorithm is mainly researched and theperformance of the algorithm is simulated by Matlab. The simulation results show theinferiority of traditional coherent integration method for weak signal acquisition. Afterthat, the influence of several main factors on the coherent integration algorithm forweak signal acquisition is described.Secondly, several traditional high-sensitivity acquisition methods for the GPSweak signal are analyzed in this paper, that is, the non-coherent integration algorithm,differential coherent integration algorithm, half-bits algorithm and full-bits algorithm aswell as the performance of these methods are compared by Matlab simulation. Thesimulation results show the advantages of differential coherent integration algorithmand full-bits algorithm in high-sensitivity acquisition. On this basis, a differentialmethod that estimates the optimum path of the adjacent navigation data bits isinvestigated. Then the performance of this algorithm and several traditional methods aresimulated by Matlab. The Simulation results show the advantage of this method inhigh-sensitivity acquisition. This method can not only increase the coherent integrationtime, but also reduce the loss of square. Although the calculation of this algorithm ismore complicated than those traditional algorithms, the computation complexity of thismethod can be controlled within an acceptable range by estimating the optimum path ofthe adjacent navigation data bits.Finally, on the basis of introduction of GPS modernization and the new civil signal L2C, combined acquisition algorithms of GPS L1C/A signal and L2CM signal arepreliminarily studied, Five combined acquisition algorithms are investigated in thispaper. They are compared with the traditional non-coherent acquisition algorithms for L1C/A. Simulation results show the advantage of the combined acquisition algorithms inhigh-sensitivity acquisition.