Patent ID: 6646543
Filing Date: 2003-11-11
Classification: G06K

Abstract:
For use in a system of interchanging data between a plurality of portable objects and at least one data transceiver terminal suitable for cooperating with portable objects simultaneously present in a field of action of the terminal, the terminal comprising circuitry configured to perform the following:store a collision probability modulation parameter (PMP), the value of which is a function of a mean number of said portable objects likely to be found in a field of action of said terminal; transmit a general call message to the portable objects, the general call message including said PMP; receive a general response message from each of the portable objects determined to respond to the general call message, each of the general response messages including an identifier uniquely identifying the respective portable object transmitting the general response message; in the absence of a collision between the general response messages of portable objects, establish a specific data communication link between the terminal and each portable object transmitting the general response message, respectively; and determine a collision has occurred between the general response messages of portable objects when the general response message is not received from any of the portable objects and transmit the general call message again.