一种基于声层析的河道实时流速测量系统设计与实验

Design and Experiment of a Real-Time Flow Velocity Measurement System for River Channels Based on Acoustic Tomography

针对河道实时流速测量系统存在的电源有限功率约束和河道的声传输噪声复杂问题,设计了一种基于m序列相关法的声层析河道实时流速测量系统,系统采用m序列码作为扩频发送信号来解决背景噪声干扰,在接收端使用正交解调(In-Phase and Quadrature Demodulation,IQ解调)解决同步解调信噪比低的问题。在有限电源功率下,分析了m序列的阶数、扩频倍数对时间测量的影响。系统使用了国产的RT-Thread操作系统和北斗卫星导航系统,实现各站点定位和授时。选择10阶m序列调制信号,在长江流域进行现场验证,所测流速与多普勒流速仪验证比对,两者平均误差为1.2%。

A real-time flow velocity measurement system for river channels based on m-sequence correlation method is designed to address the issues of limited power constraints and complex acoustic transmission noise in the system.The system uses m-sequence codes as spread spectrum transmission signals to solve background noise interference,and uses IQ demodulation at the receiving end to solve the difficulty of carrier synchronization.The influence of the order and spreading factor of m-sequence on time measurement is analyzed under limited power supply.The system uses domestically produced RT Thread operating system and Beidou satellite navigation system to achieve positioning and timing of each station.A 10th order m-sequence modulation signal is selected and on-site verification is conducted in the Yangtze River Basin.The measured flow velocity is compared with that of the Doppler current meter verification,and the average error between the two is 1.2%.