Distance measurement using an ultrasonic wave is suitable for environment recognition in autonomous mobile robots. Ultrasonic distance measurement with the pulse-echo method is based on determining the time-of-flight (TOF) of the reflected echoes. The pulse-echo method with pulse compression, the cross-correlation method, can improve the distance resolution and the signal-to-noise ratio (SNR) of the reflected echo. However, cross correlation of the cross-correlation method requires the high-cost digital signal processing. A sensor signal processing method of cross correlation using a delta-sigma modulated single-bit digital signal has been proposed. Cross correlation by single-bit signal processing reduces the calculation cost of cross correlation. Furthermore, cross correlation by single-bit signal processing improves the time resolution of digital signal processing. In this paper, the distance resolution of cross correlation by single-bit signal processing is evaluated by computer simulations and experiments of ultrasonic distance measurement. Distance measurement from the high-time-resolution cross-correlation function obtained by single-bit signal processing realized high distance resolution from experimental results, despite the low calculation costs.

This paper presents a new oversampling architecture for implementing phase-tracking loop that is commonly utilized for position sensors such that synchro, resolver, and incremental encoder. This architecture consists of the cascade connection of three stage: coarse-quantizing and oversampling modulation, direct signal processing, and decimation filtering. It is expected that the oversampling strategy and the signal processing increase the resolution of detecting phase as well as oversampling A/D converters. This paper shows a simplest design of the signal processing circuit and some simulation results