Patent ID: 6010074
Filing Date: 2000-01-04
Classification: G06K

Abstract:
A system for providing contactless automated data exchange with collision resolution, comprising:at least two tags, each of said tags includingmeans for outputting a first tag message, after a first period of time, in response to a first target message and another first tag message, after a second period of time, in response to a second target message, andmeans for outputting a second tag message in response to a third target message; anda target, includingmeans for outputting said first target message,means for determining if said first tag message received by said target is valid,means for outputting said third target message if said first tag message by said target is valid, andmeans for outputting said second target message if said first tag message received by said target is invalid;wherein each of the first and second periods of time is a random wait period determined by each of said tags and is a random multiple between 0 and 7 of a predetermined slot time having a duration of approximately 0.3 milliseconds and exceeding a round-trip time for transmitting a message between the target and one of the tags.