一种声线修正的查表方法

在利用时延测距的水声定位系统中，由于在海洋中存在声速梯度，声线传播发生弯曲，为了提高定位精度，提出了一种声线修正的查表方法。由射线声学理论可知，声传播距离和时间都是声线初始掠射角的函数，在声源深度、接收深度和声速分布已知的情况下，对每一个初始掠射角，必有唯一一个传播时间和距离与它相对应，根据声线的这一特征，可以用查表法通过声传播时间来确定相应的传播距离。通过建立传播时延与声源与接收机的水平距离的对应关系表，利用声线在水平面的投影水平距离通过圆交汇解算出目标的位置，而不是利用声线弯曲的斜距进行球面交汇解算出目标的位置。仿真和海试结果表明，在复杂水文条件下，该方法能有效提高水声定位精度。

A table look-up method of sound ray correction

In underwater acoustic positioning system by using time-delays estimation, sound rays often propagate along curves because of the sound velocity varying with depth. A table look-up method is established to correct the bending of sound rays for a better positioning accuracy. From the ray theory, the horizontal distance and the time of sound propagation are the function of initial grazing angles. If the source depth, receive depth and sound velocity are known, the time of sound propagation can be determined corresponding to every initial grazing angle. A table look-up method is established for the correction of sound ray by building up a relationship between the horizontal distance and the time of sound propagation. Target＇s Location can be calculated by intersecting circle radius, which is the shadow of sound ray, instead of using bending sound rays. Computer simulation and sea trial show that the correction is effective for increasing positioning accuracy under the complex hydrological condition.