Method for determining or monitoring a predetermined fill level, a phase boundary or a density of a medium

摘要

A method and an apparatus for determining or monitoring a predetermined fill level, a phase boundary or a density of a medium in a container with an oscillatable unit. The oscillatable unit is placed at the height of the predetermined fill level and is excited to oscillate successively with discrete exciter frequencies following one another in a frequency scanning operation (sweep) within a predeterminable frequency band in the working range of the oscillatable unit. The corresponding oscillations of the oscillatable unit are received in the form of received signals; wherein that exciter frequency is ascertained in the frequency scanning operation, at which the oscillatable unit oscillates with an oscillation frequency, which has a predetermined phase shift between the transmission signal and the received signal; and wherein the transmitting/receiving unit excites the oscillatable unit to oscillate with the ascertained oscillation frequency.