Airborne ultrasonic sensor node for distance measurement

In this paper, two complementary techniques are mixed in order to reduce the inaccuracies of time of flight (TOF) estimation caused by the small bandwidth of ultrasonic transducers and multipath echoes. Firstly, the destructive self-interference driving technique is used to minimize the multipath echoes effects, improving the accuracy and repeatability of the measurements. Secondly, the bandpass sampling theory is applied to digitalize the echo signal, avoiding the need of powerful and costly hardware. The proposed method was implemented on a PSoC architecture providing a cost-effective solution. The results show that a low complexity, robust and high-accuracy ultrasonic range measurement system was obtained. This work is part of a project to design an automatic level measurement system with capability to be integrated to a wireless sensor network in order to monitoring river and other kind of water stream level.