Fig. 1. Background noise removal of full waveform data of GF-7 satellite laser altimeter

Fig. 2. Full waveform data, its noise and effective signal of GF-7 satellite laser altimeter

Fig. 3. Types of the knuckle point in full waveform, and the red point is the current point (Current), the intensity is , the blue points are the chronologically adjacent with current point, and the intensities are and respectively: (a) and ; (b) and ; (c) and ; (d) and ; (e) and ; (f) and 离散全波形中折点类型，红色点为当前点(Current)，强度值为 ，蓝色点为相邻时间的两个离散点(Former, Later)，强度值分别为 和 ：(a) 且 ；(b) 且 ；；(c) 且 ；(d) 且 ；(e) 且 ；(f) 且 F

Fig. 4. Full waveform data of GF-7 satellite laser altimeter with a right-skewed peak

Fig. 5. Diagram of the left-skewed or right-skewed peak of the waveform peak in filtering window: the center point of the waveform in the filtering window is the red point, and the blue points are the adjacent points in the same filtering window. The waveform was divided into two parts with center point as the reference, and the α, β, γ, ψ, ω and θ are the slope angles calculated from the left and right parts respectively

Fig. 6. Full waveform data of GF-7 satellite laser altimeter with an unsaturated flat peak

Fig. 7. Filtering result of GF-7 satellite laser altimeter full waveform: (a) raw full waveform and the red line indicates the background noise value of waveform; (b) waveform filtering result of our proposed adaptive Gaussian filtering method; (c) sequences of standard deviation (SD) using the proposed adaptive Gaussian filter and fixed length Gaussian filters (the blue polyline, red line, and black line are corresponding to the standard deviation of adaptive Gaussian filter, fixed length (3.5 ns) Gaussian filter and fixed length (1.5 ns) Gaussian filter respectively); (d) waveform filtering result using average filter; (e) waveform filtering result using Gaussian filter of fixed length of 3.5 ns; (f) waveform filtering result using Gaussian filter of fixed length of 1.5 ns

Fig. 8. Peak simulation leveling of raw full waveform (without background noise) of GF-7 satellite laser altimeter, and the maximum amplitude of raw waveform is 58.33 mV while the amplitude of the leveling peak is 58.12 mV