QUESTION: What is the CLEF function and how does it work?

ANSWER: Constrained Leading Edge Fit (CLEF) is an algorithm used by Siemens radar level devices to extract the position of the first of two echoes that are close together. For example, in an almost empty flat-bottomed vessel, a low dK material may reflect an echo weaker than the echo from the vessel bottom. On the echo profile, the two echoes become merged, causing the device to report a material level equal to or lower than empty. The CLEF algorithm will utilize the leading edge of the merged echoes to determine the material level.