Research on Digital Filter Design for Orthogonal Decomposition Algorithm Applied in Coriolis Flow Meters

Abstract

Coriolis flow meters are used in measuring flow amount of natural gas and oil due to the good performance and high precision. Orthogonal decomposition algorithm is the most efficient algorithm with the highest precision in processing the digital signals of Coriolis flow meters, and digital filter design is vital important in the algorithm. In this paper we introduce a digital filter system combining the self-adaptive lattice notch filter and low pass filter embedded with Hanning Window or Kaiser Window, we also discussed the parameters selection and adjusting method deeply and systematically. For self-adaptive lattice notch filter, we calculate the key feedback parameter ρ based on bandwidth BW, leading the relative error of frequency calculated within 0.01%. For low pass digital filter, we adjust the filter order through monitoring the sine feature of the orthogonal component that has passed the low pass filter, and the relative errors of phase difference are within 0.1%. We also demonstrate the feasibility of this system through simulation under MATALAB system and calculating experiments data of Coriolis flow meter.