CPC B60R 25/245 (2013.01) [B60R 25/248 (2013.01); G07C 9/00309 (2013.01); G07C 2009/00555 (2013.01)] | 6 Claims |
1. A relay attack determination device configured to determine a relay attack, in which wireless communications between an in-vehicle device and a portable device are relayed by a relay device, comprising:
a transmitter disposed on the in-vehicle device, the transmitter being configured to transmit a first signal and a second signal having an output condition different from an output condition in the first signal;
a receiver disposed on the portable device and including an antenna of plural axes respectively oriented in different directions to receive the first signal and the second signal in each of the plural axes;
a strength meter disposed on the portable device to measure a reception strength of the first signal and the second signal received by each of the plural axes of the receiver;
a comparator configured to execute a comparative process of reception strength ratios in the first signal and the second signal, based upon a measurement value of the reception strength; and
a determiner configured to determine the relay attack based upon a result of the comparative process in the comparator,
wherein in a case where the plural axes include an ineffective axis in which the measurement value of the reception strength of the first signal or the second signal deviates from a usable range, the comparator excludes the ineffective axis and executes the comparative process,
wherein the strength meter comprises a RSSI circuit, and
wherein the usable range is between a lower limit value and an upper limit value of a reception strength that can be measured accurately by the strength meter.
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