针对远距离杂波环境下弹载雷达NED坐标系跟踪机动目标精度差的问题，提出一种ECEF(地心坐标系)下基于无偏UCUT-IMM的机动目标跟踪算法。该方法首先利用无偏转换把弹载雷达极坐标量测值转换到NED坐标系下的量测值，然后通过坐标旋转得到ECEF坐标系下的量测值，在ECEF坐标系下跟踪滤波，避免了远距离NED坐标系下跟踪滤波受地球曲率的影响，同时为了减少坐标非线性转换旋转所带来的误差，利用UT(不敏变换)计算出地心坐标系下的量测协方差，在此基础上采用IMM(交互多模型)算法来进一步提高目标机动时的跟踪精度。仿真结果表明，与NED坐标系下的跟踪滤波相比，该算法具有更好的跟踪精度。

To improve the maneuvering target tracking precision under the clutter background at far distance, a maneuvering target tracking algorithm was proposed based on Unbiased Conversion and Unscented Transformation under the Earth Centered Earth Fixed (ECEF) coordinate system.The measured polar coordinate data of missile-borne radar was transformed into data under NED coordinate system, and then to ECEF coordinate system.The tracking was then implemented under ECEF coordinate system.In this method, the error caused by faraway nonlinear coordinate transformation was reduced by using Unbiased Conversion and Unscented Transformation.Maneuvering target tracking precision was further improved by using IMM algorithm.Simulation results show that the proposed method has higher tracking precision compared with the tracking under NED coordinate system.