Evaluating and correcting measurement signals for determining level of medium in container, by removing interference echo signals from raw echo curve based on extraction algorithm

摘要

From a high frequency measurement signal comprising superimposed transmitted measurement signals, reflected echo signals, and interference echo signals, an intermediate frequency signal is produced by sequential sampling. A raw echo curve or digitized envelope dependent on the propagation time is produced from the intermediate frequency signal. The interference echo signals in the curve or envelope are determined in a current static reference curve and stored. The reference curve is used to produce an independent reference curve if conditions in the container are modified. The interference echo signals are removed from the raw echo curve based on a extraction algorithm that uses the independent reference curve.