Abstract: To ensure the toll collection of a vehicle carrying an in-vehicle unit without stopping the vehicle at an entrance toll gate or an exit toll gate, an entrance toll gate lane is equipped sequentially from the entrance with a vehicle class discriminator, an entrance vehicle number reader, a first antenna, a vehicle detector, a ticket issuer, a display unit, a vehicle detector, a second antenna and a start detector. The first antenna communicates with an in-vehicle unit of a coming vehicle to write the entrance toll gate data. The display unit is caused, when the communication succeeds, to permit the passage of the vehicle therethrough. When the communication fails, the display unit is caused to stop the vehicle, and the ticket issuer issues the ticket. The second antenna writes the vehicle class data and the registered number data, as detected by the vehicle class discriminator and the vehicle number reader, in an in-vehicle unit. Thus, the existing facilities can be used as they are.

Abstract: An automatic collection system for automatically collecting a toll charge from an IC card is provided with transceivers in gantries installed along a vehicle road. This collection system uses the transceivers to perform communication with a vehicle-mounted device based on the use of encrypted data. The vehicle-mounted device performs the encryption and decryption of the communication data before its entry into the communication area of the gantries and after its passage therethrough. Also, writing of the data into the IC card, etc. are also performed using encrypted data. However, an algorithm which differs from that used in encrypting the data stored in the IC card and which enables the execution of the high speed processing is used for encrypting the communication data.