Accurate distance measurement by an autonomous ultrasonic systemcombining time-of-flight and phase-shift methods

This paper presents an efficient algorithm for distance measurement, combining both the pulse time-of-flight method and the CW phase-shift method, It copes with a low-rate sampling technique allowed by the limited bandwidth of two ultrasonic transducers working in air at 30 kHz and with modest software resources of autonomous devices. The measuring system was implemented and tested on a compact Motorola MC68HC16-based platform, with a minimum of attached hardware. Experimental results show an accuracy better than 1 mm for a poor reflecting target at a distance of about 1 m     

Micro data-loggers lead to two new classes of chips

Micro-data-loggers are miniature autonomous systems intended to measure and memorize various physical parameters during a period of up to a few months or years. It is proposed that such devices be composed of only three main chips: a general management chip, a measurement chip, and a storage memory. The micro-data-loggers' context (including micropower) is discussed, and the main characteristics that such components must exhibit are described. The management chip has been realized and tested. The proposed structure of the measurement chip is based on the experience gained with several micro-data-loggers realized with standard components. The emphasis is on the programmability of the chips, which allows a broad range of applications