RFID SYSTEM WITH TIME SLOT INTERLEAVING
First Claim
1. An RFID interrogation system comprising:
- a first RFID interrogator;
a first antenna; and
a second antenna,wherein the first and second antennas located in proximity to each other and wherein the first and second antennas are located to direct signals to and to receive signals from respective first and second interrogation zones,wherein a first downlink signal from the first RFID interrogator is transmitted to the first antenna during a first downlink window,wherein a first uplink window is opened and after said first downlink window for receiving a signal from a first RFID transponder in the first interrogation zone;
wherein a second downlink signal from the first RFID interrogator or from a second RFID interrogator is transmitted to the second antenna during a second downlink window,wherein the second downlink window occurs after the first downlink window,wherein a second uplink window is opened after the second downlink window for receiving a signal from a second RFID transponder in the second interrogation zone,wherein the second RFID transponder is different than the first RFID transponder, and wherein;
said first uplink window comprises a first acquire window,said second uplink window comprises a second acquire window,said first acquire window occurs after said second downlink signal and said second acquire window occurs after said first acquire window, andsaid first and second acquire windows do not overlap in time.
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Accused Products
Abstract
A method for interleaving time slots in a multi-antenna system for communication with RFID tags is disclosed. An example is shown for an eight antenna system. A first four antennas arranged side-by-side are sequentially energized to interrogate RFID transponders. A second set of four antennas arranged side-by-side, the first of which is adjacent to the last of the first set of antennas. A four-antenna sequence is performed for the first four antennas and a second four antenna sequence is performed for the second set of antennas. The first and second four antenna sequences are offset by only a marginal amount, sufficient to ensure that a transponder signal received four antennas away from an active antenna is not acknowledged because the receive window for the non-active antenna is delayed.
9 Citations
9 Claims
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1. An RFID interrogation system comprising:
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a first RFID interrogator; a first antenna; and a second antenna, wherein the first and second antennas located in proximity to each other and wherein the first and second antennas are located to direct signals to and to receive signals from respective first and second interrogation zones, wherein a first downlink signal from the first RFID interrogator is transmitted to the first antenna during a first downlink window, wherein a first uplink window is opened and after said first downlink window for receiving a signal from a first RFID transponder in the first interrogation zone; wherein a second downlink signal from the first RFID interrogator or from a second RFID interrogator is transmitted to the second antenna during a second downlink window, wherein the second downlink window occurs after the first downlink window, wherein a second uplink window is opened after the second downlink window for receiving a signal from a second RFID transponder in the second interrogation zone, wherein the second RFID transponder is different than the first RFID transponder, and wherein; said first uplink window comprises a first acquire window, said second uplink window comprises a second acquire window, said first acquire window occurs after said second downlink signal and said second acquire window occurs after said first acquire window, and said first and second acquire windows do not overlap in time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification