Research On Phase Center Correction Method About Nulling Antenna Of Satellite Navigation

Global Navigation Satellite System(GNSS)plays an increasingly important role in military and civilian fields.However,since the power of useful signals from satellites received by receivers is very small,it is vulnerable to be interfered by other signals.The nulling antenna is a commonly used technique for suppressing interference in GNSS,it often utilizes the power inversion criterion to make the array pattern form a null in the direction of the interference by adaptive weighting processing,so that suppressing interference effectively.But the weighting processing for nulling antenna may cause the problem that the phase center is not consistent with the geometric center of antenna array.For high-precision positioning,the positioning deviation caused by this problem can't be ignored,so the correction methods for phase center must be performed.This thesis analyzes the principle of the nulling antenna commonly used in GNSS,and studies two kinds of correction methods for the phase center of the nulling antenna.The main contents include the following three parts:(1)The principle of nulling antenna is analyzed,and a new algorithm of nulling antenna for impulse interference suppression is proposed for the traditional nulling antenna can effectively suppress continuous wave interference but can't effectively suppress the impulse interference.This algorithm uses stored data to calculate the weights of two parallel paths with fast convergence speed.The two paths are independent to each other.According to whether the impulse interference exists,the corresponding weight is selected,which can effectively suppress the impulse interference.Meanwhile,the influence of channel error for received signal on the anti-interference performance of nulling antenna is analyzed.(2)The phase center correction method based on pattern calculation is researched.Firstly,the relationship between the phase direction function and the parameters of array antenna is analyzed.Then,the relationship between the phase direction function and the phase center is studied by the definition of phase center,so as to obtain the relationship between phase center and the parameters of array antenna through the transition of phase direction function,So that we can obtain the phase center coordinates of the nulling antenna by real-time calculation,and correct it to the position of geometric center.(3)The phase center correction method based on the expected signal angle is studied,which corrects the phase center from the nulling algorithm.The nulling antenna with directional constraints is studied by using the direction of the expected signal.Unlike the conventional nulling antenna,the nulling antenna with directional constraints can ensure the phase value is a constant in the main lobe range,so that we can solve the problem that the phase center is inconsistent with the geometric center in the main lobe range,and finally verified by simulation.