| 摘要 |
PROBLEM TO BE SOLVED: To provide road side radio equipment (such as road side equipment of an ETC) or the like, with which communication performance (communication reliability) can be improved in a multiplex system. SOLUTION: The road side equipment simultaneously performs transmitting of one road side antenna 23 and receiving of another road side antenna 24 (time division system). Besides, the road side antenna is separated to a receiving antenna and a transmitting antenna, the receiving antenna forms a narrow communication area covering respective lanes and the transmitting antenna forms a wide communication area (separated antenna system). Besides, when detecting the transmitting frequency of the road side antenna in a frequency dividing system, on-vehicle equipment compares a received radio wave intensity in a plurality of comparators on the stage when the frequency of a received radio wave is converted to an intermediate frequency, so that the transmitting frequency of the road side antenna can be detected. Further, by considering a difference in the radio wave intensities of respective road side antenna transmitting frequencies as well, erroneous detection caused by phasing (abnormal propagation) is prevented. |
