| 摘要 |
<p>PURPOSE: To eliminate the interference due to the conflict of answer signals and to secure the sure communication for every on-vehicle machine even when plural on-vehicle machines are included in the communication areas overlapping with each other. CONSTITUTION: A gantry containing antenna units 16 to 18 against the lanes is provided at a fare collection gate of a 3-lane expressway. The units 16 to 18 are controlled to perform their mutual transmission and transmit the signals among adjacent units in every prescribed cycle and also the non-modulated carrier radio waves. An on-vehicle machine 30 receives a signal and produces an answer signal through a control circuit 42 to transmit it by reflection. Then the machine 30 fixes the following opposite party of communication and waits for reception of a question signal. Furthermore, the machine 30 produces an answer signal after reception of a pilot signal and a question signal and also starts a timer circuit 47. When a timer interruption signal is supplied from the circuit 47 when an answer signal is produced, the circuit 42 transmits the answer signal. In such a constitution, a conflict state can be evaded against the answer signal of another machine 30.</p> |
