Emerald Group Publishing Limited
Copyright © 2000, MCB UP Limited
Keywords: Electronics, Phase change
Applicant: Pierre Raimbault (FR)Patent number: US5923251Publication date: 13 July 1999Title: Phase control method for electronic tags and station and tag implementing said method
An electronic tag and a method for remote interrogation of electronic tags from a station are provided in which, in reply to polling signals sent from a station, tags send responses which may interfere, the method comprising a step in which the tags are brought into phase before sending their response. The invention provides an electronic tag having means for communicating with the station for receiving polling signals or interrogations from the station and for sending responses back to the station, notably for implementing the method. In the case of simultaneous interrogation of several tags, the problem arises from the tags replying simultaneously or in overlapping fashion, called here "collision". Generally speaking prior art documents propose that the tags send their responses in a given format designed to be recognised by the station. In some documents, it is proposed that the response from the tags should depend on their code. The station can then check the validity of the response it has received, in order to detect collisions.