Vehicle-mounted unit for an automatic toll collection system that prevents double toll charging

Abstract

After a vehicle-mounted unit determines that a vehicle has entered a toll chargeable area, if communication is determined to be allowable through a flag, communication operations are performed and after finishing communication operations, the flag is set and communication operations thereafter are prohibited. Next, the unit determines if a travel distance has exceeded a toll chargeable distance. The travel distance is measured by counting the number of vehicular speed pulses received after the end of the communication operations, and the toll chargeable distance is set to be equal or greater than the travel distance needed by the vehicle to enter the communication area and leave it. If it is determined that travel distance has exceeded toll chargeable distance, the flag is reset, communication prohibition is released and communication thereafter is allowed.

Dependencies are inferred from the claim text.