Patent ID: 7643949
Filing Date: 2010-01-05
Classification: G01F,G01N

Abstract:
1. A method comprising: passing a fluid through a flowtube having at least two natural modes of vibration, the modes of vibration having different periods of oscillation; applying a drive signal to the flowtube such that the flowtube vibrates; receiving a first sensor signal from a first sensor that is operable to sense a vibration of the flowtube, the first sensor signal comprising a first major signal component associated with a first one of the modes of vibration, and a first minor signal component associated with a second one of the modes of vibration; receiving a second sensor signal from a second sensor that is operable to sense a vibration of the flowtube, the second sensor signal comprising a second major signal component associated with the first mode of vibration, and a second minor signal component associated with the second mode of vibration; analyzing the first received sensor signal over a time period that is defined with respect to the period of oscillation of one of the modes of vibration of the flowtube; analyzing the second received sensor signal over a time period that is defined with respect to the period of oscillation of one of the modes of vibration of the flowtube; and determining a difference between a phase of the first sensor signal and the second sensor signal based on the analysis of the first received sensor signal and the analysis of the second received sensor signal.