Bed-load discharge of a river can be monitored by indirectly measuring the acoustic pulses generated when the bed load collides with a steel pipe installed on the riverbed (i.e., pipe hydrophone measurement). However, existing methods used for filtering pulses from acoustic signals reflect a combination of bed-load collision frequency bands, thereby limiting characterization capabilities. This study proposes an improved filtering method that separates and efficiently examines frequency bands that are highly correlated with bed-load collision characteristics. Herein, an experimental hydraulic model and bed-load collision sound-measurement system were constructed, and bed-load collision experiments were repeatedly performed for collecting acoustic data using a pipe hydrophone. Fast Fourier Transform analysis was performed on data to select the specific frequency bands and pressures reflecting the bed-load particle size. Furthermore, a bandpass method to examine bed-load collision sounds is also presented herein. Results indicate that in comparison with existing filtering methods, the proposed bandpass method yields higher detection rates under bed-load conditions of low flow rate and small particle size, thereby demonstrating its enhanced effectiveness.

中文翻译：

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通过管道水听器频带分离的床载荷碰撞声过滤

通过间接测量河床荷载与安装在河床上的钢管碰撞时产生的声脉冲（即管道水听器测量），可以监测河流的河床荷载流量。然而，用于从声信号中过滤脉冲的现有方法反映了床载荷碰撞频带的组合，从而限制了表征能力。本研究提出了一种改进的过滤方法，该方法可以分离并有效检查与床载碰撞特性高度相关的频带。在此，构建了实验水力模型和床载碰撞声测量系统，并使用管道水听器重复进行了床载碰撞实验以收集声学数据。对数据进行快速傅立叶变换分析以选择反映床载粒度的特定频带和压力。此外，这里还介绍了一种带通方法来检查床负载碰撞声音。结果表明，与现有的过滤方法相比，所提出的带通方法在低流速和小粒径的床载条件下产生更高的检测率，从而证明了其增强的有效性。