| 摘要 |
<p>PURPOSE: To surely communicate with one antenna unit even at the time when a machine on a vehicle passes the area where adjacent communication areas overlap. CONSTITUTION: A gantry where antenna units 16 to 18 are provided corresponding to respective lanes is arranged in the toll collection place of a three-lane superhighway. Antenna units 16 to 18 are so controlled that adjacent antenna units transmit signals to each other alternately, and not only the signal but also a non-modulated carrier radio wave is transmitted with a prescribed period. When receiving the signal, a machine 30 on the vehicle generates a response signal by a control circuit and transmits the signal by reflection and fixes the future communication destination and is set to the interrogation signal waiting state. When a repeat pilot signal is received from the same antenna unit, the impossibility of communication is discriminated to release and invalidate fixing of the communication destination, and the state that communication with another antenna unit is possible is set. The machine on the vehicle can certainly communicate with one antenna unit even when it passes overlapping communication area, and the toll collection processing is surely performed.</p> |
