School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China.
Center for Information Geoscience, University of Electronic Science and Technology of China, Chengdu 611731, China.
Sensors (Basel). 2020 Jan 2;20(1):269. doi: 10.3390/s20010269.
The time-difference method is a common one for measuring wind speed ultrasonically, and its core is the precise arrival-time determination of the ultrasonic echo signal. However, because of background noise and different types of ultrasonic sensors, it is difficult to measure the arrival time of the echo signal accurately in practice. In this paper, a method based on the wavelet transform (WT) and Bayesian information criteria (BIC) is proposed for determining the arrival time of the echo signal. First, the time-frequency distribution of the echo signal is obtained by using the determined WT and rough arrival time. After setting up a time window around the rough arrival time point, the BIC function is calculated in the time window, and the arrival time is determined by using the BIC function. The proposed method is tested in a wind tunnel with an ultrasonic anemometer. The experimental results show that, even in the low-signal-to-noise-ratio area, the deviation between mostly measured values and preset standard values is mostly within 5 μs, and the standard deviation of measured wind speed is within 0.2 m/s.
时差法是超声风速测量中常用的方法，其核心是对超声回波信号的精确到达时间进行确定。然而，由于背景噪声和不同类型的超声传感器的存在，在实际中很难准确测量回波信号的到达时间。本文提出了一种基于小波变换（WT）和贝叶斯信息准则（BIC）的方法，用于确定回波信号的到达时间。首先，利用确定的 WT 和粗略到达时间获取回波信号的时频分布。在粗略到达时间点周围设置时间窗口后，在时间窗口中计算 BIC 函数，并使用 BIC 函数确定到达时间。该方法在超声风速仪风洞中进行了测试。实验结果表明，即使在低信噪比区域，大部分测量值与预设标准值之间的偏差大多在 5 μs 以内，测量风速的标准偏差在 0.2 m/s 以内。
