| 摘要 |
In a method of detecting redirection or interception during a bi-directional non-contact making data transmission, the attenuation (A 1 ) of the amplitude over the forward path is compared with the attenuation (A 2 ) of the amplitude over the return path. The attenuation (A 1 ) over the forward path is transmitted in encoded form with the reply signal. If the attenuation values determined thereby are of the same magnitude, then the likelihood of a redirecting process can be excluded. In order to additionally increase the security of the system, the carrier frequency (F 2 ) of the interrogation signal can also be compared with the carrier frequency (F 21 ) of the reply signal. The signals can also incorporate an ID code. |
