Implementation of High-Precision Magnetostrictive-Type Liquid Level Measurement System UsingWavelet Transform
Woo-Jin Choi* and John-Tark Lee**,†
*HANLA IMS Co., Ltd., 115 Hwajeonsandan 1(il)-ro, Gangseo-gu, Busan, Korea
**Department of Electrical Engineering, Dong-A University, 37 Nakdong-Daero 550beon-gil, Saha-gu, Busan, Korea
Precise measurement of levels of liquids stored in tanks is essential for monitoring and predicting disasters by detecting leakages or arbitrary discharge of toxic materials. Therefore, tanks are typically equipped with a series of liquid level sensors. A magnetostrictive-type level sensor is composed of a waveguide, a current pulse interrogator, and a sensing coil for detecting reflective torsional signals caused by Wiedemann effect, which is themain principle of operation of magnetostrictive-type liquid level sensors. In order to implement a high-precision magnetostrictivetype liquid level measurement system, we used time–frequency analysis techniques such as wavelet transform (WT) to precisely detect the reflected signals. By using time–frequency analysis techniques such as short-time Fourier transform (STFT) and WT, a robust and precise liquid level measurement system can be implemented even in noisy environments.
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