| Satellite navigation system plays an important role in the military and people's daily life,however due there are a lot of interference in the external environment and the satellite signal is very weak at the same time,so in the presence of band interference,the receiver is difficult to effectively receive satellite signals.In order to ensure the importance of satellite navigation system in military and daily life,it is necessary to improve the Anti-interference ability of the guidance system,so as to ensure the survivability of the airborne guidance products in the complex interference environment.The traditional Anti-interference nulling antenna in satellite navigation use the power inversion criterion to obtain the array weighting vector.Comparing to the phased array antenna array,it can produce significant nulls in the direction of interference,so as to effectively suppress the interference.But in the satellite navigation receiver,the traditional nulling antenna can not form the main lobe direction of the satellite signal,and can only produce the zero bias of the alignment interference,so that the desired signal gain can not be improved.At the same time,In order to forming different main lobe of the antenna pattern aligned to different satellite signals increasing the array gain.In this paper,the constraint conditions is constrainted,and use the minimum power criterion to solve the optimal weight vector solution of each satellite signal by the direct matrix inversion method,and then complete the beam synthesis.The proposed method can not only suppress the interference,but also can obtain a larger array gain with respect to a single antenna to improve the signal to noise ratio of the received signal.Therefore,this thesis is aimed at the research on the method of the satellite navigation Anti-interference nulling antenna beamforming synthesis.The research mainly includes the four parts:(1)Basing on the uniform linear array and planar array structure,analysising the basic principle of phased array,arbitrary planar phased array antenna receiving signal expression is derived the basic parameters of the phased array pattern and the array gain etc..(2)The study of anti nulling antenna theory based on the traditional jamming of satellite navigation,mainly about the Anti-interference technology of adaptive beamforming,and various criteria and algorithms for spatial processing based on minimum mean square error algorithm,inverse algorithm of iterative least square algorithm and matrix,finally discusses the relationship between the selection principle and adaptive filtering algorithm.(3)Study on the traditional nulling antenna beamforming method,established the mathematical model of traditional nulling antenna signal processing,the traditional power inversion algorithm,the pattern of traditional nulling antenna and the output signal power spectrum simulation analysis,the simulation results show that the array pattern does have a significant null in the interference direction,resulting in the suppression of effect of interference.(4)The difference from the traditional nulling antenna,and gives the new processing method,the new method(with direction constrained multi objective nulling antenna beamforming technology)were studied by signal processing model of the proposed method,and inverse algorithm for array simulation using direct matrix,through the simulation results,we can see that the new the method not only suppresses the external disturbance,but also overcome the mutual interference between satellite signals,formed the main lobe of each satellite signal to improve the output snr.At the same time compared to traditional nulling antenna,phased array and a new method of output signal to interference noise ratio performance simulation analysis under different input signal-to-interference-plus-noise-ratio and the number of snapshot cases,finally compares and analyses the calculation in traditional and new methods of nulling antenna.Through the simulation analysis,we can see clearly that the new method is more effective than the traditional one in order to make it more effective. |
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