The invention relates to a method for determining and/or monitoring the filling level of a medium in a container with a measuring device which operates according to the propagation time measurement method, wherein measurement signals are emitted in the direction of the medium and received, the high-frequency total measurement signal consisting of the superimposition of the emitted measurement signals, the reflected useful echo signals and the interference echo signals is used to determine a raw echo curve or a digitized envelope curve, the useful echo signals and/or the interference echo signals in the raw echo curve or the digitized envelope curve are determined using an ideal echo curve which represents the amplitude of the echo signals of an ideal reflector on the basis of the distance to the ideal reflector, and the filling level is determined using the useful echo signals determined.