固定坐标系机载双基地雷达杂波建模与特性分析

Modeling and characteristic analysis of clutter for airborne bistatic radar in fixed coordinate system

摘要:

机载双基地雷达体制下杂波的空时分布特性严重依赖双基雷达构型.针对机载双基地雷达体制,为解决载机间存在相对运动导致雷达配置场景处于时变状态的问题,论文首先构建了地面固定坐标系；然后利用坐标变换法,推导得到了双基距离和单元的解析表达式和杂波回波表达式,建立了一个时不变固定坐标系中的杂波数学模型；最后着重针对机载双基地雷达体制下杂波的空时分布特性和双基雷达构型对杂波分布的影响进行了理论分析和仿真研究,验证了该杂波模型的正确性.仿真结果表明:载机在航向一致、航向平行、航向垂直和航向相交四种不同飞行配置下,杂波分布差异较大；双基距离和越小,杂波的角度多普勒迹越分散,多普勒频率随距离变化越快,距离相关性越强；而随双基距离和增大,杂波的角度多普勒迹逐渐接近,杂波特性的距离依赖性相对减弱.固定坐标系机载双基地雷达杂波模型具有不依赖收发平台的特点,有效避免了平台运动引起的重复建模,扩展了杂波模型适用范围,为机载双基地雷达杂波抑制的研究奠定了基础.

Abstract:

The space-time distribution characteristics of clutter under the airborne bistatic radar system are heavily dependent on the configuration of bistatic radar. For the airborne bistatic radar system, to solve the problem that the radar configuration scene is in time-varying state due to the relative motion between the carriers, the fixed ground coordinate system was constructed. By using the coordinate transformation method, the analytical expression of bistatic range sum unit and the clutter echo expression were derived, and the mathematical model of clutter in a time-invariant coordinate system was established. Then the space-time distribution characteristics of clutter under airborne bistatic radar system and the influence of bistatic radar configuration on clutter distribution were theoretically analyzed and simulated, which verified the validity of the clutter model. The simulation results show that clutter distribution is greatly different under four flight configurations, i.e., consistent heading, parallel heading, vertical heading, and intersecting heading. The smaller the bistatic range sum is, the more the angle-Doppler trace disperses, the faster the Doppler frequency changes with the range, and the stronger the range correlation is. However, with the increase of bistatic range sum, clutter angle-Doppler trace gradually approaches, and range dependence of clutter is relatively reduced. The radar clutter model with fixed coordinate system is independent of the transceiver platform, which avoids the repeated modeling caused by the platform movement and extends the range of clutter model, which lays a foundation for the study of clutter suppression for airborne bistatic radar.