The biggest problem is calculating the seabed slope angle of the unknown seabed. 而对未知海底的倾斜角求解问题是解决波束角效应的难点之一。
A surveying instrument consisting of a spirit level and a sighting tube,used to measure the angle of inclination of a line from the observer to the target. 由一个水平仪和一个观测管组成的测量工具，用来测量从观测者到目标的直线的倾斜角。
