RFID label time synchronization
First Claim
Patent Images
1. A method comprising:
- in a radio frequency identification (RFID) interrogator having an antenna, transceiver, a clock, a memory and a central processing unit (CPU), initializing a RFID tag with a label start time and a time to record data, the label start time representing an actual start time indicated by the clock;
receiving a label stop time, a label time and logged data from an interrogation of the RFID tag; and
compensating the label time for a drift between the label stop time and an actual stop time by determining an actual time associated with the logged data, wherein determining the actual time comprises;
determining a product of the label time and a difference between the actual stop time and the actual start time; and
determining a quotient of the product and a difference between the label stop time and label start time.
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Accused Products
Abstract
Methods and apparatus, including computer program products, for radio frequency identification (RFID) label time synchronization. A method includes, in a radio frequency identification (RFID) interrogator having an antenna, transceiver, a clock, a memory and a central processing unit (CPU), initializing a RFID tag with a label start time and a time to record data, the label start time representing an actual start time indicated by the clock, receiving a label stop time, a label time and logged data from an interrogation of the RFID tag, and compensating the label time for a drift between the label stop time and an actual stop time.
18 Citations
17 Claims
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1. A method comprising:
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in a radio frequency identification (RFID) interrogator having an antenna, transceiver, a clock, a memory and a central processing unit (CPU), initializing a RFID tag with a label start time and a time to record data, the label start time representing an actual start time indicated by the clock; receiving a label stop time, a label time and logged data from an interrogation of the RFID tag; and compensating the label time for a drift between the label stop time and an actual stop time by determining an actual time associated with the logged data, wherein determining the actual time comprises; determining a product of the label time and a difference between the actual stop time and the actual start time; and determining a quotient of the product and a difference between the label stop time and label start time. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A computer program product, tangibly embodied in a machine readable storage device, for adjusting a time in a radio frequency identification (RFID) system, the computer program product being operable to cause a data processing apparatus to:
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in a radio frequency identification (RFID) interrogator having an antenna, transceiver, a clock, a memory and a central processing unit (CPU), initialize a RFID tag with a label start time and a time to record data, the label start time representing an actual start time indicated by the clock; receive a label stop time, a label time and logged data from an interrogation of the RFID tag; and compensate the label time for a drift between the label stop time and an actual stop time by determining an actual time associated with the logged data, wherein the computer program product is further operable to cause the data processing apparatus to determine the actual time by; determining a product of the label time and a difference between the actual stop time and the actual start time; and determining a quotient of the product and a difference between the label stop time and label start time. - View Dependent Claims (8, 9, 10, 11)
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12. A radio frequency identification (RFID) interrogator comprising:
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an antenna linked to a transceiver; and a programmable memory and central processing unit linked to the transceiver, wherein the memory is programmed to adjust times in an interrogated RFID label in which data including time is logged, the programmed memory causing the central processing unit to; initialize a RFID tag with a label start time and a time to record data, the label start time representing an actual start time indicated by the clock; receive a label stop time, a label time and logged data from an interrogation of the RFID tag; and compensate the label time for a drift between the label stop time and an actual stop time by determining an actual time associated with the logged data, wherein determining the actual time comprises; determining a product of the label time and a difference between the actual stop time and the actual start time; and determining a quotient of the product and a difference between the label stop time and label start time. - View Dependent Claims (13, 14, 15, 16, 17)
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Specification