Field verification test in UTMS's emergency call system

The purpose of UTMS's emergency call system is to help speedy rescue operation for traffic accidents. The cellular phone is a rapid and effective method to report an emergency but is difficult in determining the accident location. To solve this issue, this emergency call system plans to incorporate onboard equipment with a position detection function (such as GPS) which will transmit the necessary information via the existing cellular communications infrastructure. Evaluations of position determination accuracy were carried out using a variety of onboard equipment configurations. The authors also evaluated the reliability of the digital cellular communication protocol in communications between the vehicle and the center. The results allow to establish the main guidelines for the communication method between onboard equipment and center. Also, quantitative knowledge of reported position accuracy is obtained for assisting actual operation of the system.