Patent ID: 7477059

Claim:
A method to determine and signalize the contents level of a first fluid stored in a container and to evaluate a potential presence of a second fluid below the first fluid, comprising the steps of: generating microwave measurement signals in a level measurement apparatus mounted on the container; transmitting said microwave measurement signals to a wave guide extending into the container; guiding said microwave measurement signals on the wave guide towards the first fluid in the container and the potentially present interface between the first and second fluid; guiding reflected measurement signals on the wave guide back to the level measurement apparatus; generating a measurement curve in relation to the length of the wave guide; scanning such measurement curve for a first signal peak indicating a fill level of the first fluid; scanning such measurement curve for a second signal peak relative to a bottom region of the wave guide; if a second signal peak is identified in the measurement curve a phasing of the second signal peak is compared to a phasing of the first signal peak; a presence or absence of a second fluid below the first fluid in the container is determined; the contents level of the first fluid is determined in consideration of a present contents or absence of the second fluid in the container; and whereby the presence of the second fluid is indicated in the case: where the second signal peak has the same phasing or polarity as the first signal peak, and where it is presumed that the second fluid has a higher dielectric constant than the first fluid.