Patent ID: 8567243

Claim:
A method for the fill level measurement in a container, in which a quantity of a first fill substance and/or a quantity of a second fill substance are/is located, wherein the first fill substance has a smaller specific weight than the second fill substance, and the two fill substances have different dielectric constants, wherein the method comprising the steps of: sending an electromagnetic signal into the container; on at least one media boundary produced by the fill substances present in the container, a reflection takes place, in the case of which a part of the signal is reflected; measuring the travel time required for the path to such media boundary and back, for each reflected part of the signal, dependent on the position of the media boundary causing the reflection; measuring a capacitance between a capacitive probe and a reference electrode, dependent on the amounts of fill substances located in the container; ascertaining a position on the basis of the measured capacitance and the measured travel times for each fill substance present in the container, which corresponds to the position, which the fill substance upper surface of the respective fill substances assume due to the amount of the first fill substance present in the container and the amount of the second fill substance present in the container, when the entire amount of each fill substance in the container forms a single layer containing only such fill substance; creating a hypothesis for which media boundary the reflection decisive for the measured travel time has taken place for the case in which only one travel time could be ascertained; ascertaining on the basis ofthe easured travel time, for each fill substance present in the container, the measured capacitance and the hypothesis, the positions, which the fill substance upper surfaces of the respective fill substances assume due to the amount of the first fill substance present in the container and the amount of the second fill substance present in the container, when the entire amount of each fill substance in the container forms a single layer containing only such fill substance; checking for correctness the positions ascertained on the basis of the hypothesis and on the basis of the physical boundary conditions; and repeating the method with a changed hypothesis, in the case the check shows a disagreement.