Research On Technology Of GPS Receiver Robust Adaptive Beamforming

Global Position System(GPS) is widely used in military and civilian fields, for its all-time, all-weather characteristics. Since Satellite navigation receiver is exposed in increasingly complex environment, the received signal is are very weak, and a variety of man-made interference signals are accompanied, GPS is susceptible to a variety of interferences. In order to ensure the normal work of the GPS receiver, eliminate the effects of the spatial interference and improve the signal to interference plus noise rate(SINR) of the ouput, we study the robust beamforming for the GPS receiver in this thesis. The main work in this paper is as follows:Firstly, the theoretical knowledge of GPS signal and signal processing technology are introduced,including the basic thereoy of GPS signal,array signal processing model and the basic criterion of optimal statistical beam forming.Besides, Several beamforming algorithms are presented,they are minimum variance .distortionless response(MVDR) beamforming algorithm and sample matrix inversion(SMI) beamforming algorithm. The influences to the adaptive beamforming algorithm cased by antenna array error factors and seering vector mismatch are analyzed at the same time, thus the robust adaptive beamforming algorithm: the diagonal loading(DL) adaptive beamforming and eigenspace(ESB) beamforming are improved.Secondly, the classical Invasive Weed Optimization algorithm is introduced to solve the problem of beam forming.since this algorithm is easy to fall into local optimal solution, the convergence speed is low and the accuracy is low,in this paper,an rapid weed invasion algorithm is proposed.Here, the variance function takes the S evolution curve, which makes the plant distribution variance large with large sufficiency,and the plant distribution variance small with small sufficiency.In order to futher improve the accuracy, another improved Hybrid Invasive Weed Optimization(IHIWO) algorithm is improved based on the rapid weed invasion algorithm. In this algorithm, the variance function is expressed in the form of subsection. In the initial stage of evolution, the corresponding relationship between the variance of seed distribution and the fitness of S is established, which ensures the strong global search ability at the initial optimal phase stage. In the late stage of evolution, In the late stage of evolution, the exponential curve correspondence is used to further improve the convergence precision of the algorithm. The relevant experiments have been carried out to verify the effectiveness of the IHIWO algorithm.Then, the sources of the GPS error are introduced and its influence to the GPS receiver is analyzed.Based on the algorithm of steer vector evaluation of the rotating the subspace, an new improved steer vector evaluation of the rotating the subspace is improved. According to the characteristics of input signal, this algorithm gives a specific dimension calculation formula of steering vector orthogonal subspace and constructs the K-R subspace and covariance matrix. By projecting the sample covariance matrix to the signal K-R subspace to estimate the estimation error of the sample data covariance matrix. Thus enable the ISVER to converge to high accuracy in a few snapshots.Finally, the overall structures of the GPS receiver are introduced. The IHIWO algorithm and the ISVER algorithm are respectively applied to the adaptive beamforming of GPS receiver. At the same time, the corresponding simulations are performed,which have illustrated that, GPS receiver adaptive beamforming algorithm has fast convergence ability and strong anti-jamming ability based on IHIWO algorithm, and Based on ISVER algorithm,the GPS receiver adaptive beam forming algorithm estimates the covariance matrix with high accuracy,which improves the convergence speed in the a few snapshots.