射电望远镜远场区域强干扰源规避方法研究

随着频率使用率的提高,射电天文台址地面或空间存在强电磁干扰致使望远镜接收机系统处于非线性状态.为减少强电磁干扰的影响、提高天文观测效率,提出了一种基于望远镜远场区域的强干扰源规避方法.首先,通过仿真分析确定的射电望远镜远场方向图,结合望远镜与干扰源之间的位置关系,分析了强电磁干扰到达射电望远镜焦点处的功率响应,并依据接收机第2阶中频放大器性能参数,确定射电望远镜处于非饱和状态的规避角度计算方法.其次,采用该方法计算分析了民航飞机对射电望远镜的影响,若民航飞机上有主动发射的干扰源,且不经过反射等传播现象,当射电望远镜主波束轴偏开一定方向后,可有效降低对射电望远镜的干扰强度.

Data⁃Based Feedback Relearning Algorithm for Robust Control of SGCMG Gimbal Servo System with Multi⁃source Disturbance

Single gimbal control moment gyroscope(SGCMG)with high precision and fast response is an important attitude control system for high precision docking,rapid maneuvering navigation and guidance system in the aerospace field.In this paper,considering the influence of multi-source disturbance,a data-based feedback relearning(FR)algorithm is designed for the robust control of SGCMG gimbal servo system.Based on adaptive dynamic programming and least-square principle,the FR algorithm is used to obtain the servo control strategy by collecting the online operation data of SGCMG system.This is a model-free learning strategy in which no prior knowledge of the SGCMG model is required.Then,combining the reinforcement learning mechanism,the servo control strategy is interacted with system dynamic of SGCMG.The adaptive evaluation and improvement of servo control strategy against the multi-source disturbance are realized.Meanwhile,a data redistribution method based on experience replay is designed to reduce data correlation to improve algorithm stability and data utilization efficiency.Finally,by comparing with other methods on the simulation model of SGCMG,the effectiveness of the proposed servo control strategy is verified.

基于频率方差加权的抗干扰目标方位估计方法研究

常规水声宽带信号通常采用宽带分频带无差异融合处理，当空间存在强干扰时，弱目标线谱成分易被淹没，影响被动声纳系统的抗干扰目标方位估计性能。利用目标舰艇辐射噪声中线谱成份稳定性强、线谱频率方差远小于噪声频率方差的特点，本文提出了基于频率方差加权的抗干扰目标方位估计方法。仿真结果表明，该方法在目标线谱信息未知的情况下，可有效抑制宽带无线谱成分强噪声干扰源的影响，准确估计弱目标方位。