基于等效地球半径的超短波超视距时差定位方法

超视距无线传输条件下的超短波辐射源目标高精度定位技术是非合作通信侦测中亟待解决的难点问题；针对该难题，在考虑地球曲率影响的同时，提出采用等效地球半径模型对超短波信号的对流层散射信道进行修正，在此基础上构建全新的基于到达时间差的定位方程组；通过Chan算法与牛顿迭代法相结合，对该非线性方程组进行求解，从而实现了辐射源目标空间位置的获取；详细推导了不同坐标系下坐标的转换计算、TDOA方程组的求解算法、定位性能的客观评价参数——几何精度因子；通过仿真分析了时差测量精度对定位精度的影响，并对提出的等效地球半径模型进行了仿真验证，结果表明，该模型可以有效降低超视距定位误差，并且随着距离的增加，定位性能的提升效果更明显，实现了对超短波超视距辐射源目标的高精度定位，具有较高的工程应用价值。

Ultrashort Wave Over the Horizon Time Difference of Arrival Method Based on Equivalent Earth Radius

The high-precision positioning technology of ultrashort wave radiation source targets under the condition of over the horizon wireless transmission is a difficult problem that urgently needs to be solved in non-cooperative communication detection; To address this challenge, while considering the influence of earth curvature, an equivalent earth radius model is proposed to modify the tropospheric scattering channel of ultrashort wave signals. Based on this, a new positioning method group based on Time Difference of Arrival is constructed; By combining the Chan algorithm with the Newton iteration method, the nonlinear equation system was solved to obtain the spatial position of the radiation source target; Detailed derivation of coordinate conversion calculations in different coordinate systems, algorithms for solving TDOA equations, and objective evaluation parameters for positioning performance - Geometric Dilution of Precision; The impact of time difference measurement accuracy on positioning accuracy was analyzed through simulation, and the proposed equivalent Earth radius model was validated through simulation. The results showed that the model can effectively reduce the over-the-horizon positioning error, and with the increase of distance, the improvement of positioning performance is more obvious, achieving high-precision positioning of ultra-short wave over-the-horizon radiation source targets, which has high engineering application value.