供水管道泄漏定位中基于互谱的时延估计

供水管道泄漏时产生泄漏声波，根据泄漏声波到达安装在管道上的2个传感器的时间差可以估计泄漏位置。减小时延估计的方差必须对信号滤波以提高信噪比，但泄漏信号所在的频带是不能预先确知的。互谱相位谱和相干函数在频域上反映了2个信号的相关性，根据它们估计泄漏信号的频带、设定滤波器截止频率，在较低信噪比的情况下提高滤波效果及检测结果的置信度。实际检测结果表明，该方法减小了泄漏定位的误差。

Time delay estimation based on cross-power spectrum for water pipeline leakage locating

Water supply pipeline leakage generates noise. The leakage position is estimated from the time difference that the leakage sound takes to reach two sensors installed at the access points of the pipeline. To reduce the variance of the time delay, the sound signal needs to be filtered to enhance the signal-to-noise ratios (SNR). However the frequency band of the leakage signal is not known beforehand. Cross-power spectrum phase and coherence function reflect the relation between two signals in the frequency domain. Basing on this idea, the frequency band of the leakage signal is estimated and the cut-off frequencies of the filters are set. This technique improves the filtering effect and the confidence of estimation in the case of low SNR. The field test results indicate that the proposed method reduces the error of leakage locating.