| 摘要 |
PROBLEM TO BE SOLVED: To provide such an on-vehicle automatic sensitivity adjusting circuit in an ETC (electronic toll collection) system, which can correspond to a plurality of applications. SOLUTION: This on-vehicle automatic sensitivity adjusting circuit consists of a means for deciding an optimum application at a position at which a vehicle currently travels, reference voltage generating means for storing a plurality of reference voltage defined in each application and generating a reference voltage fitting the application decided by the optimum application deciding means, and a means for comparing the reference voltage with a received signal obtained by applying and shaping the received radio wave in the each application and switching the on-vehicle machine to be communication when the received signal voltage is higher than the reference.
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