Abstract: An ultrasonic non-contact motion monitoring system, useful for monitoring motional activities and such activities as respiration rate and heart beat rate. Using dual ultrasonic transducers, coherent sound waves are directed toward a moving subject. The phase frequency relationship of the reflected waves are compared to the transmitted sound waves in-phase and in phase-quadrature. The derived information, containing movement activity, is either displayed locally or sent to remote station(s) for display, processing and storage.