Patent ID: 6321982
Filing Date: 2001-11-27
Classification: G06K

Abstract:
A method for identifying one or more electronic cards by an interrogation unit, each electronic card assigned a unique identification number, the method comprising:(a) transmitting a general interrogation message within an investigation zone;(b) receiving one or more response messages from the one or more electronic cards present within the investigation zone responsive to the general interrogation message, each response message comprising a variable number; and(c) reconstructing according to a tree-like iterative algorithm each response message for the identification number corresponding to an electronic card, the reconstructing comprising(c.1) if at least two response messages are received simultaneously, then identifying a value of a group of i bits of an identification number of an as yet unidentified electronic card present and, in looping to (a), transmitting a particular interrogation message having a parameter k assigned a value of i, and(c.2) if a single response message is received, then identifying a group of j as yet unidentified last bits of the identification number of an electronic card present so that the electronic card is identified and, in looping to (a), transmitting a general interrogation message.