California Partners for Advanced Transportation Technology

This document specifies the theory of operation of version B of the PATH ultrasonic range control board for the IBM PC. Two modes are discussed in detail. The first is the ping mode, which uses a single transducer both to send an ultrasonic pulse and receive its echo. The second, called the phased-array mode, uses a single transducer to send the pulse and two other transducers to receive echoes and perform path-length matching in order to reduce the effects of multi-path echoes. Both the hardware and the software used to perform these functions are examined.