| 摘要 |
<p>The method operates as an access system of the 'hands free' type which permits access to a closed space, such as the interior of an automobile. Remote exchange of data with a recognition device installed in the closed space and an identifier designed to be carried by a user. Access is only authorized when the recognition device has authenticated the identifier. Data exchange at the same radio frequency is established, called RF exchange, e.g. at 315, 434 or 868 MHz, between the recognition device and the identifier. During the course of the data exchange, the transmission of a response signal by the identifier to the recognition device for a period (tau) of about 0.8 micro seconds, with respect to the reception by the identifier of an interrogation signal from the recognition device, so that neither the recognition device nor the identifier operate simultaneously whilst transmitting or receiving the RF exchange.</p> |
