John Kelly Watkins

US Patent:

52032094, Apr 20, 1993

Filed:

Feb 25, 1991

Appl. No.:

7/660380

Inventors:

John L. Watkins - Pasadena CA
Martin B. Barmatz - Glendale CA

Assignee:

The United States of America as represented by the Administrator of the
National Aeronautics and Space Administration - Washington DC

International Classification:

G01P 1304

US Classification:

73505

Abstract:

A system is described for determining motion of an object that is acoustically positioned in a standing wave field in a chamber. Sonic energy in the chamber is sensed, and variation in the amplitude of the sonic energy is detected, which is caused by linear motion, rotational motion, or drop shape oscillation of the object. Apparatus for detecting object motion can include a microphone (24) coupled to the chamber and a low pass filter (40) connected to the output of the microphone, which passes only frequencies below the frequency of sound produced by a transducer (18) that maintains the acoustic standing wave field. Knowledge about object motion can be useful by itself, can be useful to determine surface tension, viscosity, and other information about the object, and can be useful to determine the pressure and other characteristics of the acoustic field.