Patent ID: 8639457

Claim:
A method for ascertaining and monitoring the fill level of a medium in a container by means of a field device of automation and process control technology, comprising the steps of: transmitting transmission signals toward the medium and receiving them as reflection signals by means of a transmitting/receiving unit of the field device; registering the transmission signals and the reflection signals by means of data points in an envelope curve dependent on travel time or travel distance; registering disturbance echo signals by means of data points in a masking curve ascertained in a first measuring cycle from the envelope curve of an empty container; ascertaining an evaluation curve from the envelope curve by a smoothing procedure in a first measuring cycle; connecting data points of the envelope curve, the evaluation curve and/or the masking curve with one another via connecting functions and intermediate values are thus produced; reducing the number of data points in the masking curve and/or in the evaluation curve by means of a reduction algorithm improving processability of the masking curve and/or the evaluation curve; and ascertaining at least one wanted echo signal in the current envelope curve by an echo search algorithm, by means of the reduced masking curve and/or the reduced evaluation curve.