| 摘要 |
[Object] To provide a signal processing method, a signal processing apparatus, and a Coriolis flowmeter, which may always perform measurement with constant precision and performs phase measurement with high filtering performance and a small amount of computation even when a temperature of a fluid to be measured changes, air bubbles are mixed into the fluid to be measured, or the fluid to be measured rapidly changes from a gas to a liquid. [Solving Means] In a Coriolis flowmeter, a phase difference and/or a vibration frequency proportional to a Coriolis force acting on at least one flow tube or a pair of flow tubes are/is detected, to thereby obtain a mass flow rate and/or density of the fluid to be measured. The Coriolis flowmeter includes A/D converters for converting, into digital signals, analog signals output from velocity sensors or acceleration sensors which are a pair of vibration detection sensors, a pair of quadrature frequency modulators for performing frequency conversion on the digital signals which correspond to the pair of vibration detection sensors, a frequency measurement unit for measuring a frequency based on one digital signal output from the pair of vibration detection sensors, and a transmitter for generating a frequency signal corresponding to ¸(1-1/N) of a digital signal of the frequency. A phase difference is obtained based on the signals generated by the quadrature frequency modulators. |
