Research On Key Technology Of Distributed Array Receiving Coherence On Mobile Platform

As a new type of radar,distributed array radar has the characteristics of strong detection ability,strong survivability,high angle resolution,strong scalability and easy implementation.It has become an important development trend and research hotspot in the field of modern radar systems.Compared with the ground-based distributed array radar,the distributed array radar applied to the mobile platform can greatly improve the mobility,flexibility and survivability of the radar;Moreover,the distributed coherent radar algorithm can be applied to multiple flight platforms,with good scalability;For different types of targets,the array can be changed freely,the number of array elements can be added or deleted freely,and the performance of distributed array system can be improved.However,because of the flexible formation of the mobile platform,it also brings more gate lobes and error problems.Based on this background,this thesis studies two key technologies of receiving coherence,namely,gate lobe suppression and error correction,for distributed array of moving platform.The main work of this thesis can be summarized as follows:1.In response to the gate lobe problem of distributed arrays on mobile platforms,a frequency synthesis and space frequency combination gate lobe suppression algorithm based on genetic algorithm is proposed on the basis of existing algorithms for optimizing formation and suppressing gate lobes based on genetic algorithm.The formation optimization algorithm mainly reduces the amplitude of gate lobes by changing the spacing of array elements;The frequency synthesis algorithm mainly utilizes the characteristic that the main lobe position of the array pattern formed by different frequency beams is the same,but the gate lobe position is different,to enhance the main lobe and suppress the gate lobe by multiplying the directional patterns of multiple frequencies.By using genetic algorithm for frequency screening,the optimal frequency can be selected for synthesis,achieving the optimal gate lobe suppression effect;The space frequency combination algorithm combines formation optimization and frequency synthesis,using genetic algorithm to simultaneously screen the formation and frequency,select the optimal formation and synthesis frequency,and further suppress the generation of gate lobes.Compared to formation optimization and frequency synthesis,the space frequency combination algorithm has a more significant suppression effect on gate lobes,making it suitable for applications in scenarios with larger spacing between distributed array elements on mobile platforms.2.Aiming at the systematic error of distributed arrays on moving platforms,this thesis derives the corresponding relationship between power loss and phase error based on the far field model;Then,the closed form solutions of signal power loss under Gaussian and uniform phase errors are derived,and the effects of phase errors on signal power loss under both distributions are simulated and analyzed;Finally,the factors that affect the system error of the distributed array of moving platforms are analyzed,and the relationship formula between the synthesis efficiency and the system error is derived.A set of conditions that need to be satisfied for each system error corresponding to the 90%synthesis efficiency under the Gaussian distribution and uniform distribution of phase errors are given.This part of the research on phase error is conducted from two aspects:Gaussian distribution and uniform distribution,breaking the traditional limitation that phase error only obeys Gaussian distribution.3.Aiming at the problem of system error correction of distributed array on moving platform,this thesis proposes to apply the external calibration source technology to the system error correction of receiving coherence of distributed array on moving platform.The main principle of external calibration source correction technology is that a known transmitter transmits a beam,and the system error is obtained by comparing the actual beam phase received by each array element of the distributed array with the theoretical value.However,there will be inaccurate positioning of the calibration source,which will affect the correction of the system error.To solve this problem,this thesis proposes a TSWLS+Iterative joint positioning algorithm considering the array element position error,which greatly improves the positioning accuracy of the calibration source and realizes the application of the external calibration source technology on the mobile platform distributed array.