基于浅海多径时延的复合码水声测距研究

针对浅海环境单发单收水声测距方法运算复杂度较高、易受水下特殊环境影响的问题,提出一种低复杂度且适用于水声多径信道的测距方法。首先将复合码作为同步测距信号应用于水声测距系统,支持快速、准确的信号同步和多径时延检测,然后提出改进加权函数的广义互相关(GCC)算法提取多径时延,最后引入匹配函数将多径时延与传播路径正确匹配,并结合双曲线、三角形等几何方法计算收发端之间的距离。仿真结果表明,在多径及低信噪比(-10 dB)环境下,复合码同步捕获准确率达100%且运算复杂度较低,与相位变换-广义互相关(PHAT-GCC)算法相比,改进加权函数的GCC算法多径时延检测性能提高了将近6 dB,在此基础上,实现了单接收节点对水下目标的测距。

Research on underwater acoustic ranging with composite code using multipath delay in shallow sea

Aiming at the problems that the single-shot and single-acquisition water-acoustic ranging method in the shallow sea environment has high computational complexity and is susceptible to the special underwater environment, a low-complexity ranging method suitable for underwater acoustic multipath channels is proposed. Firstly, the composite code is applied to the underwater acoustic positioning system as a synchronous ranging signal, which supports fast and accurate signal synchronization and multipath delay detection. Then, an improved weighting function generalized cross correlation (GCC) algorithm is proposed to extract the multipath delay. Finally, a matching function is introduced to multiply the multipath delay. The path delay is correctly matched to the propagation path, and the geometrical methods such as hyperbola and triangle are used to calculate the distance between the transmitting and receiving ends. Simulation results show that in multipath and low signal-to-noise ratio ( - 10 dB) environments, the synchronization accuracy of the composite code is 100% and the computational complexity is low. Compared with the phase transformation-generalized cross correlation (PHAT-GCC) algorithm, the multipath of the GCC algorithm with an improved weighting function is improved. The delay detection performance is improved by nearly 6 dB, and based on this, a single receiving node can achieve ranging of underwater targets.