| 摘要 |
<P>PROBLEM TO BE SOLVED: To attain low power consumption by lowering a frequency of erroneously transmitting a signal even though a receiving state is determined to be satisfactory when a station on the street transmits a radio wave signal outside a communication area due to some influence and the an electronic number plate side receives the radio wave signal. <P>SOLUTION: An electronic unit 2 of the electronic number plate shifts to a normal operation mode to communicate with a device on the street on the conditions that the electrical field intensity level of a radio wave signal transmitted from the device A on the street is equal to or greater than a prescribed level and that the electric field intensity level of radio wave signals transmitted from other vehicles C2 to C4 is equal to or greater than a prescribed level in a state set in a low power consumption mode. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
