echo arrival meaning in English

回波初至

The claim has been made upon the results that the wmt method should be used in the area near the vertical , while the phase difference method in slant beams and a rule has been given to select among those two methods according to the " effect value " on condition the depth is known for the consideration of improving the measurement precision , this paper studies the factors which affect the toa measurements , and three expressions of precision has been introduced as to applications of phase difference method , this paper introduces an automatic hunting method based on amplitude power to get the range of echo arrival
采用方差分析的方法，使用重复海试数据对wmt法和相位差法的优劣进行了分析，指出了垂直附近应该使用wmt法，而倾斜波束应该使用相位差法；给出了在深度真实值已知前提下wmt法和相位差法使用的判决准则，即根据效应值的大小来选择。本文从提高测量精度角度出发，分析并验证了影响toa测量精度的因素；给出了三种精度表示。在应用相位差法时，引入了一种基于幅度能量的区间自动搜索方法；实验表明该方法能很好地确定回波到达的大概时间范围。