Cross-Correlation by Single-bit Signal Processing for Ultrasonic Distance Measurement

Shinnosuke HIRATA  Minoru Kuribayashi KUROSAWA  Takashi KATAGIRI  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E91-A   No.4   pp.1031-1037
Publication Date: 2008/04/01
Online ISSN: 1745-1337
DOI: 10.1093/ietfec/e91-a.4.1031
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Selected Papers from the 20th Workshop on Circuits and Systems in Karuizawa)
ultrasonic distance measurement,  pulse-compression technique,  delta-sigma modulation,  cross-correlation,  moving average filter,  

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Ultrasonic distance measurement using the pulse-echo method is based on the determination of the time of flight of ultrasonic waves. The pulse-compression technique, in which the cross-correlation function of a detected ultrasonic wave and a transmitted ultrasonic wave is obtained, is the conventional method used for improving the resolution of distance measurement. However, the calculation of a cross-correlation operation requires high-cost digital signal processing. This paper presents a new method of sensor signal processing within the pulse-compression technique using a delta-sigma modulated single-bit digital signal. The proposed sensor signal processing method consists of a cross-correlation operation employing single-bit signal processing and a smoothing operation involving a moving average filter. The proposed method reduces the calculation cost of the digital signal processing of the pulse-compression technique.