Method and apparatus for sensor calibration in a dewatering system
First Claim
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1. 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.
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Abstract
A dewatering system includes a selective calibrating sensor circuit configured to receive sensor readings from an electronic sensor, to determine if the electronic sensor is immersed in water, and to generate a control output signal accordingly. The selective calibrating sensor circuit periodically performs a self-calibration when the electronic sensor is not immersed in water to cancel the effect of potential contaminants deposited on the electronic sensor over its operating life. The selective calibrating sensor circuit inhibits calibration when the electronic sensor is immersed in water.
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Citations
12 Claims
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1. A dewatering system comprising:
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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. - View Dependent Claims (2, 3, 4, 5)
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6. A method for sensor calibration, the method comprising:
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providing a first sensor reading from a first capacitance sensor to a sensing circuit; comparing the first sensor reading with a first reference sensing level in the sensing circuit to generate a first water detection signal that indicates whether the first capacitance sensor is immersed in water; and executing a calibration algorithm that disables calibration of the sensing circuit when the first water detection signal indicates that the first capacitance sensor is immersed in water and selectively enables calibration of the sensing circuit when the first water detection signal does not indicate that the first capacitance sensor is immersed in water, wherein the first reference sensing level is adjusted during calibration to effectively cancel errors in the first sensor reading due to accumulative contamination deposited on the first capacitance sensor. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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Specification