Merrill Engineering Laboratories, Inc.

Richard J Shelquist

Michael W Fellinger

Distance measurements are made using two or more signal frequencies. Ultrasonic energy is transmitted from a transducer to an object. Returned ultrasonic energy is received by the transducer and processed to provide an accurate determination of the distance between the transducer and the point on the object receiving the ultrasonic energy. In connection with the processing, a number of relationships are utilized. Using certain of the relationships, a range of integers is determined using high and low frequency ultrasonic energy, as well as propagation time. A time-related phase shift determination is also made for each of the high and low frequencies using certain of the other known relationships. Using a range of distance values and the measured time-related values, an accurate determination of distance from the transducer to the object can be made. In one application, a number of different distance values are obtained to define the surface plane of the object, such as a wheel or tire.

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Longmont, CO, United States of America

Richard J Shelquist