Abstract: A positioning system includes an actuator, valve (preferably pneumatic), position sensor and an electronic valve controller, integrated in a single unit. Continuously variable setpoints are possible within the range of operation. A preferred control circuit includes a signal converter, a ramp generator to smooth the shape of the command or target value signal applied, a position feedback sensor to report the actual position of the actuator, a controller, and a driver, containing an H-bridge, for controlling the pneumatic valve which feeds air into the actuator mechanism. Integration of all these components into a single unit shortens signal paths, improves resistance to electrical noise, and permits faster response time.

Abstract: A distance amplitude compensation system is disclosed herein for comparing received signals with a reference signal having a time varying amplitude. The preferred embodiment of the invention disclosed herein is particularly adapted for use in an ultrasonic nondestructive testing system to vary the reference signal of the system as a function of time to compensate for variations of the echo signal produced by changes in the amplitude of the ultrasonic energy as it propagates through the workpiece as a result of attenuation or other causes. A pulser/receiver transmits ultrasonic signals into the workpiece, receives echo signals returned therefrom and produces received signals corresponding to the echo signals. A distance amplitude compensation generator produces a reference signal that has an amplitude that varies with time as a function of the manner in which the ultrasonic energy changtes as it propagates through the workpiece.