Subcentimeter Precision Ranging System for Moving Targets With a Doppler-Effect- Compensated Ultrasonic Direct Sequence Spread Spectrum

In this article, we present a Doppler-effect-compensated ranging system that can be applied to subcentimeter-precision ultrasonic distance measurement for moving targets using a direct sequence spread spectrum (DSSS). First, the theory of the Doppler compensation technique is explained, and then, the evaluation results obtained using maximum-length-sequence coded ultrasonic signals are discussed. In this study, we employ a 128-b DSSS code with three wavelengths per bit. The experimental results demonstrate that the proposed system can measure a target accelerating at 9.8 m/s
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with a speed of up to 2 m/s in the range of 0.1-1.6 m, with a standard deviation of less than 5 mm. We also confirmed by simulation that the system can track a target accelerating at 30 m/s
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with a speed of up to 5.5 m/s in the range of 4-6 m.