湍流大气传输中跟踪抖动对远场影响的仿真研究

Simulation study on influence of tracking jitter on far field in turbulent atmospheric transmission

  • 摘要: 分析了跟踪抖动对湍流大气传输远场光斑的影响。基于麦克斯韦电磁场理论,采用大气相干长度对大气湍流进行描述,推导了发射光束因跟踪抖动导致光轴偏离的远场表达式。在此基础上,利用相位屏法模拟抖动引起的倾斜相位和大气折射率起伏引起的相位调制,并采用低频补偿的功率谱反演法对传输过程进行了数值仿真。分析了不同跟踪抖动、湍流强度条件下远场光斑质心脱靶量的变化,以及不同尺寸模拟目标的回波概率。分析结果表明,在传输距离为10 km时,强湍流造成的远场光斑脱靶量可达几十μrad;当跟踪抖动较大时,湍流强弱对脱靶量影响差别很小。最后,对一定尺寸的模拟目标,从探测回波概率的角度给出了发射系统跟踪抖动量的控制范围。

     

    Abstract: The influence of tracking jitter on the far-field spot of turbulent atmospheric transmission is analyzed. Based on Maxwell's electromagnetic field theory, the Fried coherence diameter is used to describe the atmospheric turbulence, and the far-field expression of the transmitted beam due to optical axis deviation caused by tracking jitter is derived. The method of phase screen is used to simulate the tilt phase caused by tracking jitter and phase modulation caused by atmospheric refractive index fluctuation. Fast Fourier Transform Subharmonic Method is used to simulate the transmission process. The changes of miss distance of far-field spot under different tracking jitter and turbulence intensity and the echo probability of the simulated targets in different sizes are analyzed. The analysis results show that when the transmission distance is 10 km, the miss distance of far-field spot caused by strong turbulence can reach dozens of microradians. When the tracking jitter is large, the influence of turbulence on the miss distance is very small. Finally, for the simulation target of specific size, the control range of the transmission system tracking jitter is given.

     

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