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星载激光测高仪通过提取激光回波参数计算卫星与地表的距离,结合轨道和姿态信息生成激光脚点的三维坐标。普通高斯光束的空间能量分布随光斑半径增加迅速衰减,不利于探测复杂和分层的地表目标,而平顶高斯光束可以克服这一缺点。根据平顶高斯光束和激光测高回波的相关理论推导得出平顶高斯激光模式下回波波形主要参数的解析式,并使用波形模拟器、波形处理算法,以及地球科学激光测高系统(GLAS)真实回波对所得理论模型进行了验证,结果显示不同阶数激光脉冲的对比偏差都小于3%,且随着目标斜率或阶数的增加,回波宽度和距离误差也随之增加,4阶平顶高斯光束目标斜率0.05时对应的距离误差超过10 cm。
The satellite-based laser altimeter calculates the distance between the satellite and the ground by extracting the laser echo parameters, and generates the three-dimensional coordinates of the laser foot with the orbit and attitude information. The spatial energy distribution of an ordinary Gaussian beam decays rapidly with increasing spot radius, which is not conducive to the detection of complex and layered surface targets. The flattened Gaussian beam can overcome this disadvantage. According to the theory of flattened Gaussian beam and laser altimetry echo, the analytical formulas of the main parameters of echo waveform in flat-topped Gaussian laser mode are deduced. The waveform simulator, waveform processing algorithm and the geodetic laser altimetry system ( GLAS). The results show that the contrast deviation of laser pulses with different orders is less than 3%, and the echo width and distance error also increase with the increase of target slope or order, The corresponding distance error of the 4th order flattened Gaussian beam target slope of 0.05 is more than 10 cm.