椭圆高斯足印对星载激光测高仪测距值及其误差的影响

Effect of elliptic Gaussian footprint on range and range error for satellite laser altimeter

光束空间分布是影响星载激光测高仪测距指标的重要因素。根据星载激光测高仪接收脉冲回波分布特点,通过对椭圆高斯足印及线性目标的理论建模,基于接收脉冲回波信号时间重心及其方差的基本定义,构建了椭圆高斯足印对星载激光测高仪测距值及其误差的影响模型。以GLAS星载激光测高仪为输入条件,利用数值仿真分析的方法,针对倾斜度和粗糙度分别为(3°,1.7 m)、(12.5°,8.9 m)和(28.2°,14.5 m)的三种典型观测目标,系统论述了椭圆高斯足印的椭圆率与方位角对测距值及其误差的影响规律。结果表明,激光测距值基本与椭圆高斯足印的椭圆率和方位角无关,其测距值余量最大值不超过1 mm,但是,激光测距误差会随着椭圆高斯足印的椭圆率和方位角的增加产生起伏变化,其测距误差余量最大值达到了47.04 cm。所得结论对于星载激光测高仪的硬件设计和性能评估具有一定实际应用价值。

Spatial distribution of the beam is an important factor of affecting range indicators for satellite laser altimeter. According to the distribution characteristic of received pulse signal and definition of the received pulse signal′ s time-centroid and its variance, the influence models of elliptic Gaussian footprint on range and range error for satellite laser altimeter were built, by modeling theoretically the elliptical Gaussian footprint and the linear target. Based on parameters of Geoscience Laser Altimeter System(GLAS), as for three typical observation target with slope degree and roughness(3 °, 1.7 m),(12.5°, 8.9 m)and(28.2°, 14.5 m), the influences of the elliptical Gaussian footprint ′ s ellipticity and azimuth on the range and range error were discussed systematically with the ways of numerical simulation. The results show that laser range almost has no relation with the elliptical Gaussian footprint ′s ellipticity and azimuth,its maximal difference is less than 1 mm. However, laser range error will fluctuate markedly with the elliptical Gaussian footprint′s ellipticity and azimuth, corresponding maximal difference reaches 47.04 cm.The conclusions provide practical application values for hardware design and performance assessment of satellite laser altimeter.