Study on match filtering based on sequency spectrum characteristics of the Walsh transform for electromagnetic flowmeter signal measurement

The signal processing techniques are crucial in applying the electromagnetic flowmeter (EMF), and its filtering mechanism directly influences the measurement accuracy. Considering heavy noise frequently contaminates EMF signals, a sequency match filtering method based on the Walsh transform for processing EMF signals is proposed for the first time. The proposed method can accurately match the signal's sequency and realize excellent harmonic extraction by analyzing features of the sequency spectrum. For method effectiveness validation, it not only has a high signal-to-noise ratio (SNR > 75 dB) in theoretical filtering but also has a low relative indication error (e < 2%) in experiments on the water flow calibration and the slurry flow measurement and a low E-n number (E-n < 0.5) on performance evaluation, which indicates that the proposed method enables the efficient and accurate extraction of EMF signals.