Research On Main Lobe Interference Suppression Method Based On Multistatic Radars

With increasing threats of military radar,the radar engineering has gotten great progress in recent decades.The detection distance of the radar is farther and farther and the measurement accuracy is higher and higher.At the same time,the performance of the jammer is also growing more and more excellent.Nowadays,jammers can quickly detect radar signals and then analyze and store them in a short time.In addition to being able to radiate traditional noise suppression interferences,they can also radiate a variety of spoofing interferences which could lead to radars' false decisions.The complex and changing electromagnetic environment makes that the traditional monostatic radar can not meet the need of modern warfare.The transmitter and receiver of monostatic radars are integrated together,so it is easy to be detected by a jammer and accurately interfered,which is strategically not conducive to the initiative of the war.In the modern warfare,it is becoming increasingly important for radars to whether have excellent survivability and anti-jamming capability or not.Multistatic radars is a feasible way to solve this problem.Compared with the monostatic radar,their transmitters and receivers can be far apart in space.The receivers themself does not transmit a signal,so jammers are more difficult to detect the position of receivers.In addition,multiradar systems can combine the information of all receiving stations.So they has higher resolution and better anti-jamming capability than monostatic radar.Traditional main lobe interference suppression method are studied first in this paper.The main lobe interference suppression methods based on block matrix preprocessing(BMP)and feature projection preprocessing(EMP)are studied emphatically.Through theoretical analysis and experimental simulations,the following conclusions are drawn: The above two methods are only effective to the situation that the interference direction and the expected target direction have a relatively large difference.These traditional main lobe interference suppression methods would be ineffective when the direction of interferences and the direction of targets is close or even coincident.The target signal will be suppressed when the main lobe interference is suppressed.Considering shortcomings of traditional main lobe interference suppression methods,We propose the main lobe interference suppression method based on multistatic radars in this paper.The spatial-temporal correlation function between echoes from different receivers is deduced in the case of no prior information.According to the correlation function,We define the high correlation area and the low correlation area in the paper.In the low correlation area,echoes of the target from different receiving stations are not correlated.So even if directions of interferences and directions of desired targets are close or even coincident in the region,it can retain the target signal while suppressing interferences.Finally,it can be seen from experimental simulations that the proposed method has a good effect on noise suppression interferences.However,the method is ineffective for false target interferences because the power of false target interferences is relatively small and their duration is short,which will lead to a failure of estimating interference signals in a pulse repetition period.For the problem that the suppression effect is not ideal for false target interferences,the multi-period feature projection false target interference suppression algorithm is proposed.Since target signals and interferences are independent of each other,which will result in the Cross-section of signal echoes and interferences being independent of each other during multi-period.Introducing the idea of spectral estimation,we can assume that the target echoes and false target interference signals come from different spaces.By solving the eigenvector corresponding to interference signals and constructing the feature projection matrix,and then we preprocess multi-period signals.The preprocessing operation can suppress interference signals but target signals are not affected.According to experimental results,it can be seen that proposed multi-period feature projection false target interference suppression algorithm has a good effect.