Doppler shift compensation technique for ultrasonic DSSS ranging system

Abstract

We present a Doppler effect compensation technique that can be applied to high-precision ultrasonic distance measurement using the direct sequence spread spectrum (DSSS). In this study, first, the theory of Doppler compensation technique is explained, and then the experimental results using the M-sequence coded ultrasonic signals are discussed. The evaluation results show that the proposed method can measure distance of target moving at 2 m/s in the range of 0.1–1.6 m, with an efficiency of more than 95%, and with a standard deviation of less than 8 mm by using either a 128-bit or a 32-bit long DSSS code.