Cross-Correlation and Sine-Fitting Techniques for High-Resolution Ultrasonic Ranging

This paper presents a combination of two techniques for high-resolution ultrasonic distance measurements in air. The first is the cross correlation between transmitted and received signals to determine the time of flight (TOF), and the second is sine fitting of other transmitted and received signals to determine the phase shift (PS) between them. Sine fitting can estimate the PS with very high accuracy. The result of this synergy is a very accurate distance measurement. For example, the final uncertainty is less than 100 mu m for distances up to 1200 mm.