Patent ID: 7360418

Claim:
A method for determining a level of a liquid in a tank, comprising: providing a tank in which a liquid level is variable; measuring a baseline characteristic of a probe circuit including a probe associated with the tank while the probe is out of contact with the liquid in the tank; starting a filling of the tank from a level at which the probe is out of contact with the liquid; measuring a first characteristic of the probe circuit after measuring the baseline characteristic and during filling of the tank; determining the liquid level in the tank corresponding to about a time that the first characteristic is measured based on the first characteristic and the baseline characteristic; wherein if the step of determining determines that the liquid is out of contact with the probe, the method further comprises: assigning an updated value as the baseline characteristic based on a characteristic measured during filling of the tank; measuring a second characteristic of the probe circuit after measuring the first characteristic and during filling of the tank; and determining the liquid level in the tank corresponding to about a time that the second characteristic is measured based on the second characteristic and the updated baseline characteristic.