A method for measuring a fill level of a fill substance in a container and for monitoring at least one predetermined fill level (LMIN, LMAX), using a fill level measuring device working according to the travel-time principle, as well as a corresponding fill level measuring device, wherein the monitoring...http://www.google.co.uk/patents/US7826309?utm_source=gb-gplus-sharePatent US7826309 - Filling level measurement device and filling level measurement and monitoring method
