In order to detect a filling process, a signal is emitted into the container and an echo reflected from the container is recorded. At least one parameter, e.g., the amplitude h(t) of the reflected echo at a time t, is determined, and a filling process is detected if the parameter lies outside an expected...http://www.google.co.uk/patents/US6829932?utm_source=gb-gplus-sharePatent US6829932 - Method and device for detecting a filing process
