GF-7星载激光测高仪全波形自适应高斯滤波

全波形星载激光测高仪通过向地表发射激光，获得目标表面的后向散射完整波形，可用于地表剖面高程信息及目标表面几何物理参数的反演。GF-7星载激光测高仪部分原始波形存在噪声显著、波峰左偏/右偏和非饱和平峰等情况，对提取有效信息造成干扰。针对GF-7星载激光测高仪全波形数据，首先提出了一种波形背景噪声迭代去除方法，然后对波形噪声特点及几何结构进行分析，并进行定量化描述，最终设计了一种顾及波形噪声与结构异构的自适应高斯滤波器。在实验中，将文中方法与已有经典波形滤波算法进行比较，最终验证了文中方法在噪声去除、有效信号保留及非饱和平峰波形处理上的有效性。使用文中方法进行波形滤波后，波形信噪比更高，同时波形幅值下降量均在3倍的噪声标准差以内，非饱和平峰波形滤波后波形高斯分解参数振幅、均值和标准差的分解精度分别为(0.69 ± 2.34) mV, (0.007 ± 0.024) ns和(0.026 ± 0.069) ns。

Adaptive Gaussian filtering of the full waveform of GF-7 satellite laser altimeter

The full-waveform satellite laser altimeter is able to record the complete backscattered echo waveform from the target surface, which can be used for range measurement and geophysical parameters inversion of the target surface. Some received raw full waveforms of the GF-7 satellite laser altimeter contain significant noise, skewed wave peak, and unsaturated flat peak, causing interferences to the information extraction from waveform. Firstly, an iterative method for waveform background noise removal was proposed, then, the characteristics and geometric structure of the waveform noise were analyzed and quantitatively described, and finally, an adaptive Gaussian filter considering the noise and heterogeneity structure of the waveform was designed. Comparison between the proposed method and other existing classical filtering methods was made in the experiment, and the superior performance of proposed method was proved in noise removal, signal retention, and unsaturated flat peak waveform processing. The higher signal-to-noise ratio (SNR) of the filtered waveform was achieved using the proposed method, and the amplitude decline of the waveform is within 3 times of the noise standard deviation. After the filtering of the waveform with unsaturated flat peak, the decomposition precision of the waveform Gaussian parameter amplitude, mean value and standard deviation are (0.69 ± 2.34) mV, (0.007 ± 0.024) ns and (0.026 ± 0.069) ns respectively.