OFF-RESONANCE CYCLING FOR CORIOLIS FLOWMETERS

A method is provided comprising the steps of exciting a vibration mode of a flow tube (130, 130′), wherein first and second drivers (180L, 180R) are amplitude modulated out of phase from each other, and wherein a drive command provided to the first and second drivers (180L, 180R) comprises a sum of N+1 independent signals. The first and second drivers (180L, 180R) are excited with a plurality of off-resonance frequencies and the effective phase between a modal response and the drivers (180L, 180R) at each of the off-resonance frequencies is inferred. A left eigenvector phase estimate is generated for each of the off-resonance frequencies. A phase of a left eigenvector at a resonant drive frequency is estimated based on off-resonance frequency phase estimates. The method also comprises measuring the phase between a first pickoff (170L) and a second pickoff (170R) and determining a phase of a right eigenvector for the flow tube (130, 130′).