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

摘要

After a vehicle-mounted unit determines that a vehicle has entered a toll chargeable area (101, 301), if communication is determined to be allowable through a flag F (102), communication operations are performed (103, 303) and after finishing communication operations, the flag F is set and communication operations thereafter are prohibited (104). Next, the unit determines if a travel distance N has exceeded a toll chargeable distance A (105, 307). The travel distance N is measured by counting the number of vehicular speed pulses received after the end of the communication operations (Steps 201, 202), and the toll chargeable distance A 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 N has exceeded toll chargeable distance (307), the flag F is reset, communication prohibition is released and communication thereafter is allowed (106). MATH