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星载激光测高仪多模式回波是由多个目标产生的子脉冲组合而成。根据多模式目标的空间分布特点,采用倾斜角、区域面积、中心位置和高度等参数实现其子目标的几何化建模,结合目标响应函数的基本定义,利用线积分的方式构建了子目标响应函数的表达形式。同时,基于一阶矩理论推导出子目标激光测距真值及其修正值的数学模型。以星载激光测高仪GLAS系统参数为输入,利用数值分析的方法,模拟出子目标倾斜角、面积和位置对接收脉冲回波形态和激光测距修正值的影响。结果表明,随着子目标倾斜角、区域面积和子目标偏离光斑中心距离的增加,激光测距修正值也逐渐增大。针对平坦目标、缓坡目标和陡坡目标,其激光测距修正值分别达到1.33 m、4.98 m和12.07 m,其影响程度非常大。基于激光测距修正值的分布规律,以子目标倾斜角、面积和中心偏距为变量,采用线性函数描述了激光测距修正值的理论表达形式,所得结论对于提升多模式激光测距值的测量精度具有重要的指导作用。
The satellite-based laser altimeter multi-mode echo is a combination of sub-pulses generated by multiple targets. According to the spatial distribution characteristics of multi-mode targets, the geometrical modeling of sub-targets is achieved by using parameters such as tilt angle, area, center position and height. Combined with the basic definition of target response function, sub-target response Function expression. At the same time, the mathematical model of sub-target laser ranging true value and its correction value is deduced based on first-moment theory. Taking the GLAS system parameters of spaceborne laser altimeter as input, the effect of sub-target tilt angle, area and position on received pulse echo morphology and laser range correction was simulated by numerical analysis. The results show that with the increase of the sub-target tilt angle, the area of the sub-target and the deviation of the sub-target from the spot center, the laser ranging correction value also gradually increases. For flat targets, gentle slope targets and steep slope targets, the laser range correction values reach 1.33 m, 4.98 m and 12.07 m, respectively, and the influence is very large. Based on the distribution rule of the laser ranging correction value, the linear expression of the laser ranging correction value is described by taking the sub-target tilt angle, area and center offset as the variables. The results are very helpful to improve the multi-mode laser range finding value Measurement accuracy has an important guiding role.