Patent ID: 8143894

Claim:
Method for operating a resonance measuring system having at least one oscillation element, at least one oscillation driver and at least one oscillation sensor, wherein the oscillation element, comprising the steps of: using by the oscillation driver to excite the oscillation element to oscillation in at least one eigenform with known excitation signals F i (t) and exciting the oscillation element to oscillation with unknown excitation signals W(t) by a process being measured and detecting the oscillations of the oscillation element with the oscillation sensor and forming the oscillations detected into at least one response signal y i (t) of the respective eigenform; wherein orthogonal projection components (Re{y i },Im{y i }) of the response signal are created by projecting the response signal y i (t) onto an orthogonal frame of reference, wherein at least a first value corresponding to the eigenfrequency f 0i of the resonance measuring system is determined with at least a part of alternating components of the projection components (Re{y i },Im{y i }), wherein at least a second value corresponding to the eigenfrequency f 0i of the resonance measuring system is determined with at least a part of constant components of the projection components (Re{y i },Im{y i }), and wherein the determined first and second values corresponding to the eigenfrequency f 0i of the resonance measuring system are used for exciting the resonance measuring system with at least one control in at least one control loop in a eigenform corresponding to the eigenfrequency f 0i .