This article describes the intelligent transponder, developed by the American company AT/Comm Inc, which enhances a vehicle's intelligence, provides vehicle-roadside communications, and brings the driver into the information loop, thus providing a platform for many Intelligent Transportation Systems (ITS) applications. To perform its functions, it has a microprocessor at its centre, uses an active, discrete radio transmitter and receiver, and an LCD display, keypad, and audio speaker. This enables an advanced CDMA-based multiple access approach to locating vehicles in a toll lane. AT/Comm's mobile unit can perform the following functions that would otherwise be done centrally: (1) toll calculation; (2) verifying sufficient funds; (3) vehicle location; (4) account balance adjustment; and (5) notifying the driver. Moving these processes to the transponder reduces the amount of communication equipment and services needed. A key to the transponder's effective use is its use of full-duplex two-channel communications.
Abstract