Patent ID: 7696710

Claim:
A method of determining an amount of moisture on a surface of a substrate, said method comprising the steps of: transmitting a transmitter signal to generate a vibrational wave; propagating the vibrational wave to vibrate the substrate; detecting the vibrations of the substrate; convening the vibrations into a receiver signal; sensing the temperature of the substrate; and compensating for a phase shift between the transmitter signal and the receiver signal attributable to the temperature of the substrate to determine the amount of moisture on the surface; wherein said step of compensating includes determining a measured phase shift corresponding to at least one of the amount of moisture on the surface and the temperature of the substrate; wherein said step of compensating includes determining a temperature phase shift attributable to the temperature of the substrate; wherein said step of determining the temperature phase shift includes ascertaining the temperature phase shift as a function of the temperature of the substrate; and wherein said step of determining the temperature phase shift includes storing the temperature phase shift as a function of the temperature of the substrate in a table.