Patent ID: 7134341

Claim:
A method for determining the resonance frequency of a vibratable resonator, the method comprising the steps of: subjecting said resonator to a sonic beam having one or more resonator exciting frequencies for exciting vibrations of said vibratable resonator and a carrier frequency capable of being frequency modulated by vibrations of said vibratable resonator, said carrier frequency is higher than said one or more resonator exciting frequencies; receiving returning signals from said vibratable resonator; and processing said returning signals to determine the resonance frequency of said vibratable resonator, wherein said step of processing comprises the steps of processing said returning signals to determine for each exciting frequency of said one or more resonator exciting frequencies the amplitude of at least one Doppler shifted frequency component of said carrier frequency to obtain a set of amplitude and frequency data points, and computing from said set of amplitude and frequency data points the resonance frequency of said vibratable resonator, and wherein said resonator exciting frequencies are frequencies in the vicinity of the resonance frequency of said vibratable resonator.