Research On Spoofing Suppression Algorithm For GNSS Based On Synthetic Array

Global Navigation Satellite System(GNSS)has been used in many fields,such as military affairs,society,civil and so on.However,GNSS is extremely weak to various interference.Among them,spoofing is hidden because its power level below noise floor and spoofing has the same format with authentic satellite signals both in the time domain and frequency domain,which brings a great threat to the security of GNSS.Therefore,it is necessary to use a new method to suppress the spoofing effectively based on its feature.In the existing spoofing suppression method,the multi antenna technology can separate the authentic satellite signal from spoofing by using the spatial arrival angle information of the received signal.However,it’s performance is affected by the channel error and the array aperture.Therefore,considering the idea of synthetic aperture radar(SAR),this paper using a single antenna to form a synthetic array instead of the traditional antenna array for spoofing suppression.In this paper,we study the methods of spoofing suppression with synthetic array from the following aspects.First,the principle of spoofing and synthetic array is analyzed,and the model of signal received by synthetic array is presented;Second,a scheme to suppress the spoofing with synthetic array in data domain is proposed.Under the synthetic array data model in data domain,the MUSIC algorithm and the conventional RELAX algorithm are used to estimate the DOA of multiple spoofing source.Then the adaptive weight vectors are designed to place a nulling to suppress the spoofing.Without considering the position error of synthetic array,the performance of proposed method are the same with traditional array,and is better than the performance of the traditional array with channel errors,which prove the advantages of the synthetic array;Third,in order not to be limited by the time interval between the virtual elements of synthesized array,this thesis proposes a spoofing suppression scheme of using a reference antenna.Firstly,do the conjugate point multiplication with the moving antenna data and the static antenna data.Then,the real-valued RELAX algorithm is used to estimate the DOA of spoofing and suppress it.The proposed algorithm is not limited by the time interval of the virtual elements,and has better performance of estimation and interference suppression;Fourth,a robust spoofing suppression scheme for synthetic array with trajectory error is proposed for the case that the orbit of synthetic array is not completely accurate and controllable.The weight vector of each PRN is estimated by the despread respreads algorithm,and then the spoofing is distinguished from the authentic signals by the correlation between the weight vectors.The algorithm does not need to estimate the direction of spoofing,and is insensitive to the position error of the array elements.