| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide the on-vehicle unit for narrow-band communication which can reduce the power consumption and never makes a communication complicated. SOLUTION: This unit is equipped with an antenna 1, a data transmitting and receiving circuit 2 which sends and receives data to and from an on-road device through the antenna 1, a 1st power circuit 3 which supplies the electric power to the data transmitting and receiving circuit 2, a received electric field intensity detecting means 11 which measures the intensity of a radio wave sent by the on-road device, a communication area detecting means 12 which recognizes a communication area on the basis of the output of the received electric field intensity detecting means 11, a power source actuating means 5 which actuates the 1st power circuit 3 according to the output of the communication area detecting means 12, and a 2nd power circuit 6 which supplies the electric power to the received electric field intensity detecting means 11, communication area detecting means 12, and power source actuating means 5.</p> |
