基于LMD降噪和互相关的声波飞行时间测量法

Acoustic Flight Time Measurement Method Based on LMD Noise Reduction and Cross Correlation

针对声学法测温中的环境噪音问题,该文提出一种基于局部均值分解(LMD)和互相关(CC)的声波飞行时间测量法。首先依据噪音水平决定是否短截信号降低模态混叠的概率;而后对信号进行LMD法分解,基于该文提出的有用分量筛选法重构降噪信号;最后通过对降噪信号的互相关运算获得声波飞行时间估值。用模拟粮仓中的实测数据,验证了所提方法的有效性。测试结果表明,环境噪音较小时,LMD-CC法与CC法、EMD-CC法、VMD-CC法表现相当;当环境噪音较大时,LMD-CC法的稳定性和准确性明显优于其他3种方法;与EMD-CC法、VMD-CC法相比,LMD-CC法在运行速度上有明显优势。

Aiming at ambient noise in acoustic temperature measurement,an acoustic flight time measurement method based on local mean decomposition(LMD)and cross correlation(CC)was proposed.Firstly,according to the noise level,whether to truncate the signal to reduce the probability of mode aliasing is determined.Then,the signal is decomposed by using the LMD method,and the noise reduction signal is reconstructed based on the useful component screening method proposed in this paper.Finally,the estimation of acoustic flight time is obtained by cross-correlation calculation of noise reduction signals.The effectiveness of the proposed method is verified by the measured data in the simulated granary.The test results show that when the environmental noise is low,the performance of LMD-CC method is comparable to CC method,EMD-CC method,and VMD-CC method.When the environmental noise is high,the stability and accuracy of LMD-CC method are significantly better than the other three methods.Compared with EMD-CC and VMD-CC methods,LMD-CC method has significant advantages in operating speed.