Weak Vortex Signal Extraction Method Based on a Multiple Cross-Correlation Algorithm

In vortex flow meters, measurement precision at lower velocities and turndown ratios is low. To address this problem, a digital signal processing method that combines a fast Fourier transform (FFT) spectrum analysis algorithm and a multiple cross-correlation algorithm is proposed. First, the frequency range of the signal is calculated using the FFT, spectrum analysis algorithm, and then the appropriate cycle's data are selected. The multiple cross-correlation algorithm is used to process the data to obtain ideal signal data. Simulation and experimental results show that the signal-to-noise ratio of the vortex signal can be effectively improved and the weak vortex signal that is drowned in the noise can be detected using the multiple cross-correlation algorithm. Thus, the value of vortex flowmeter measurement at lower velocity is extended.