Method for operating a contactless ultrasound or radar fill level measuring device and contactless ultrasound or radar fill level measuring device practicing said method

A contactless fill level measuring device comprising:

• at least one open distribution transmitter for emitting a transmitter signal,
• at least one receiver for receiving a reflection signal reflected on a reflector, and
• at least one evaluation unit having means for evaluating at least one of the transmitter signal and the reflection signal,
• wherein, in an operating state, the evaluation unit is adapted for identifying a frequency shift between the transmitter signal and the reflection signal and for identifying a filling event by evaluating the identified frequency shift or a variable derived from the identified frequency shift resulting from a filling stream at least partially passing through the transmitter signal,
• wherein, in the operating state, the evaluation unit is adapted for determining a reflection speed from the identified frequency shift and for detecting the filling event by comparing the reflection speed to a predetermined speed limit;
• and
• wherein the evaluation unit is operative for outputting occurrence of the detected filling event.