US Patent 7576641 Identification information examination method and information obtaining apparatus

In an identification information examination mode, reception sensitivity of a reception device in an information obtaining mode is reduced. In the reception device, information transmitted from a transmission device mounted in a vehicle adjacent to the host vehicle is not received, and identification information transmitted from a transmission device mounted in the host vehicle is received. Then, an examination is performed by comparing the received identification information with the identification information stored in memory in advance.