摘 要 摘 要 本文导出了在激光卫星通信系统下, 一种窄带 、 时 空高斯脉冲在纯净空气弱 大气湍流下传播时的瞬时展宽和瞬时闪烁的简易分析 表达式 。瞬时展宽是根据瞬 时平均强度的 处的点得到的, 瞬时闪烁的计算包括了强度的二阶量 。通过双 频互相关函数和四频交叉相关函数分别得到强度一阶 和二阶量的积分表达式 。分 析了根据修正的 谱的折射指数起伏和 湍流模型上得到 的近似积分式 。计算了上层大气 交叉结合 ( 近场 ) 和上行 下行通信传 播路径 ( 远场 ) 具体的数值结果 。根据高度为常量和 变量时, 分析了远场水平传 播和斜程传播时的瞬时脉冲展宽和瞬时闪烁指数, 讨论了大气湍流强度, 外尺度, 初始脉冲宽度, 发射波束的波束半径, 天顶角, 内尺 度, 以及光波波长对瞬时展 宽和瞬时闪烁指数的影响, 对相关数值计算结果进行 比较和验证, 结果表明影响 闪烁的决定性参数是大气湍流强度, 外尺度和发射脉冲脉冲宽度 。 关键词 :大气湍流 高斯波束 传播 瞬时展宽 瞬时闪烁指数 A BSTRACT III A BST RAC T Simple analytic expressions are derived for the temporal broadening and scintillations of a narrow band, space-tim e G aussian pulse propagating through clear-air w eak atm ospheric turbulence in a laser satellite com m unication system. The tem poral broadening is deduced from the 1 e 2 point of the tem poral m ean intensity and calculation of the tem poral scintillations involves the second m oment of intensity. Integral representations for the first and second m oment of intensity are obtained by means of the tw o-frequency m utual coherence function and four-frequency cross-coherence function, respectively. The integrals, which are present with the modified Von K arm an spectrum m odel for the refractive-index fluctuations and the Hufnagel-Valley turbulence profile mode are analyzed. N um erical implementations are given for both upper atm osphere U AV-UAV cross-links (near field) and uplink/downlink com m unication propagation paths (far field). The
