Electronic architecture for air coupled ultrasonic pulse-echo range finding with application to security and surface profile imaging

Ultrasonic range finding instruments are utilized, e.g., for measuring liquid levels and distance to parking obstacles. However, instruments designed using the conventional electronic architectures to drive the ultrasonic transmitters cannot provide an operating range beyond a few meters for a flat solid wall with normal incidence when powered by a low voltage battery. This both limits the applicability of the existing instruments and makes it difficult to demonstrate their feasibility for new applications. The architecture described here combines a DC/DC boost converter with semiconductor switches, enabling a scalable increase in the operating range for both pulse-echo and pitch-catch modes of operation. It was fully prototyped and successfully tested for novel applications involving ultrasonic range finders, specifically intrusion detection and surface profile imaging. The limitations of the profile sensing device are rather restrictive as it only operates at the incidence angles below 18°, but this device can be developed further. The developed security system was found to be quite practical in its present state.