Patent ID: 8869597

Claim:
A method for operating an apparatus for determining and/or monitoring at least one physical process variable of a medium, which apparatus has an oscillatable unit, comprising the steps of: oscillating the oscillatable unit to oscillate by means of a first frequency sweep within a predetermined frequency band in the working range of the oscillatable unit using transmission signals with successive, discrete exciter frequencies of increasing or decreasing frequency; receiving corresponding oscillations of the oscillatable unit in the form of received signals; ascertaining a first exciter frequency, in the case of which, during the first frequency sweep, at least one predeterminable criterion is fulfilled; oscillating the oscillatable unit to oscillate by means of a second frequency sweep within the predetermined frequency band in the form of transmission signals with the same successive, discrete exciter frequencies; running through the frequency band, compared with the first frequency sweep, in opposite direction; receiving the corresponding oscillations of the oscillatable unit in form of said received signals; ascertaining a second exciter frequency, in the case of which, during the second frequency sweep, the at least one predeterminable criterion is fulfilled; and determining a measuring frequency for determining and/or monitoring at least one process variable, via formation of an average from said first exciter frequency and said second exciter frequency.