Acoustic Proximity Ranging in the Presence of Secondary Echoes

Proximity ranging is very important in many applications. Ultrasonic sensors have proven to be very cost effective tools for this purpose. Most of the currently available time-of-flight based acoustic proximity ranging systems use the conventional matched filter based time delay estimation approaches to measure short distances between proximity objects. However, in the presence of strong and closely spaced secondary echoes, the aforementioned matched filter based algorithms tend to fail or suffer from severe performance degradations due to their poor resolutions. In this paper, a computationally efficient time delay estimation algorithm, referred to as multiecho parameter estimation for acoustic ranging systems, is described for the joint proximity range estimation and secondary echo mitigation. The effectiveness of the proposed algorithm is demonstrated by both numerical and experimental examples.