Patent ID: 8869587

Claim:
A dewatering system comprising: a first capacitance probe configured to detect for the presence of water at a first level in a container; a second capacitance probe configured to detect for the presence of water at a second level in the container; and a self-calibrating sensor circuit configured to receive respective outputs of the first capacitance probe and the second capacitance probe, to inhibit calibrating itself when the respective outputs indicate that at least one of the first capacitance probe and the second capacitance is immersed in water, and to periodically calibrate itself when the respective outputs indicate that both the first capacitance probe and the second capacitance probe are not immersed in water, wherein the self-calibrating sensor circuit adjusts one or more internal reference sensing levels during calibration to cancel effects on the respective outputs of the first capacitance probe and the second capacitance probe due to deposits or non-water substance in contact with the first capacitance probe and the second capacitance probe.