Geospatial Information Collaborative Innovation Center

Wuhan, China

Geospatial Information Collaborative Innovation Center

Wuhan, China

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Yang C.,Wuhan University | Hu W.,Wuhan University | Luo M.,Wuhan University | Sun Y.,Wuhan University | And 2 more authors.
Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | Year: 2016

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. © 2016, Editorial Board of Journal of Infrared and Laser Engineering. All right reserved.


Zhou H.,Wuhan University | Zhou H.,Geospatial Information Collaborative Innovation Center | Li S.,Wuhan University | Li S.,Geospatial Information Collaborative Innovation Center | And 3 more authors.
Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | Year: 2015

Noise is an important factor of affecting range error for satellite laser altimeter with recording waveform. According to the distribution characteristic of received pulse signal and noise, the theoretical expression form about variance of time-centroid for received pulse signal was deduced. Thereby, the impact model of noise on range error was built-up. Base on the principle of minimizing range error, an optimization design method for low-pass filter was put forward. In terms of basic measurement parameters for Geoscience Laser Altimeter System(GLAS), the distribution regularities of range error and RMS pulse width for low-pass filter were simulated. As for linear target of geometrical parameters within 40° slope angle and 15 m roughness, the extent of range error is 0.28 -32.49 cm. Correspondingly, the scope of RMS pulse width for low-pass filter is 1.4-57.4 ns. Aimed at targets with scope of 1° slope angle, the computed value of low-pass filter for GLAS is 2.2 ns, which is close approximate to 2 ns as published practically value. Meanwhile, on basis of optimizational results for low-pass filter, the range errors decrease significantly. The maximum of range error is decreased to 10.93 cm and corresponding reduction level gets 3 times. All the results show that impact model of noise on range error and optimization design method for low-pass filter is correct. They provide practical application values for hardware design and performance assessment of satellite laser altimeter. ©, 2015, Chinese Society of Astronautics. All right reserved.


Wang L.,Wuhan University | Zhou H.,Wuhan University | Zhou H.,Geospatial Information Collaborative Innovation Center | Li Z.,Wuhan University | And 3 more authors.
Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | Year: 2015

The Terrestrial Target Response Function (TTRF) of satellite laser altimeter is the key factor for evaluating its performance. According to the distribution characteristics of transmitted Gaussian laser beam and the target response function, the methods of using equal-interval concentric rings and dividing circumference uniformly were utilized to achieve the discrete triangular mesh of target. Based on the homogeneity of the triangular mesh and error model about characteristic parameters of TTRF, a new parameter selection method of TTRF was presented in terms of the simulation error index. In light of geosciences laser altimeter system (GLAS) parameters, the TTRF waveform distribution of planar target with three typical slope targets (3° and 12.5° and 12.5°) and multiple planar targets were simulated, by restricting the allowance error of its characteristic parameters within 2%. The calculated error is less than 1.16%, which proved that the method on simulation of TTRF is correct. The results have some application values for the simulation on received signal waveform of laser altimeter, data inversion and the performance evaluation. © 2015, Editorial Board of Journal of Infrared and Laser Engineering. All right reserved.

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