Modulation index (depth) based grouping, addressing, and fingerprinting RFID tags

• US 9,727,763 B2
• Filed: 12/31/2014
• Issued: 08/08/2017
• Est. Priority Date: 12/31/2014
• Status: Active Grant

• Current Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Original Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Inventors: Nikitin, Pavel, Kelly, Stephen J.
• Primary Examiner(s): MILLER, BRIAN E
• Application Number:
  US14/587,772
• Publication Number:
  US 20160188922A1
• Time in Patent Office: 951 Days
• CPC Class Codes: G06K 7/10039 interrogator driven, i.e. synchronous
• CPC Class Codes: G06K 7/10108 interrogating only those RFIDs that fulfill a predetermined requirement, e.g. selecting all RFIDs having the same speed and moving in a cloud like fashion, e.g. on the same train; interrogating only RFIDs having a certain predetermined temperature, e.g. in the same fridge, another possibility being the active ignoring of a group of tags that fulfill a predetermined requirement, equivalent to the Boolean NOT operation
• CPC Class Codes: G06K 7/10227 loading programming parameters or programs into the interrogator, e.g. for configuring the interrogator

Abstract

A method of addressing one or more RFID devices within a group of RFID devices includes transmitting a command to respond to the group at a first modulation depth. The method further includes receiving a response from a first sub-group of RFID devices in the group that have a minimum modulation depth less than or equal to the first modulation depth. The method further includes transmitting the command to respond to the group at a second modulation depth higher than the first modulation depth. The method further includes receiving a response from a second sub-group of RFID devices within the group that have a minimum modulation depth less than or equal to the second modulation depth. The method is also directed to authenticating RFIDs by comparing a measured minimum modulation depth to a known minimum modulation depth.

Claims

1. A method of addressing one or more RFID devices within a group of RFID devices, comprising:

transmitting, to the group RFID devices at a first modulation depth, a first signal comprising a command to respond;

receiving a response to the first signal from a first sub-group of RFID devices in the group, the first sub-group of RFID devices having circuitry that only responds to signals that have a minimum modulation depth of less than or equal to the first modulation depth;

transmitting, to the group at a second modulation depth, a second signal comprising a command to respond, wherein the second modulation depth is higher than the first modulation depth; and

receiving a response to the first and second signals from a second sub-group of RFID devices within the group, the second sub-group of RFID devices having circuitry that only responds to signals that have a minimum modulation depth less than or equal to the second modulation depth.

2. The method of claim 1, further comprising:

performing singulation on the first sub-group.

3. The method of claim 2, wherein the singulation is performed using the Q-algorithm.

4. The method of claim 1, further comprising:

associating the first sub-group of RFID devices with a first category of products; and

associating the second sub-group of RFID devices with a second category of products.

5. The method of claim 4, further comprising:

identifying a product based on a minimum modulation depth of an RFID device associated with the product.

6. The method of claim 1, further comprising:

placing one of the first sub-group of RFID devices in a first location;

placing one of the second sub-group of RFID devices in a second location; and

identifying the first or second location based on a minimum modulation depth of the RFID device at that location.

7. An RFID system, comprising;

a first group of RFID devices having a first minimum modulation depth;

a second group of RFID devices having a second minimum modulation depth higher than the first minimum modulation depth; and

an RFID communicator having;

a transmitter that transmits signals to the RFID devices; and

a controller that uses the transmitter to send a first signal to the RFID devices at a first modulation depth, and send a second signal to the RFID devices at a second modulation depth;

the first modulation depth being greater than or equal to the first minimum modulation depth and less than the second minimum modulation depth;

the second modulation depth being greater than or equal to the second minimum modulation depth;

the first group of RFID devices responding to the first and second signals; and

the second group of RFID devices responding to the second signal and not responding to the first signal.

8. The system of claim 7, wherein the controller singulates the first group of RFID devices.

9. The system of claim 8, wherein the controller uses the Q-algorithm to singulate the first group of RFID devices.

10. The system of claim 7, wherein the RFID communicator further includes:

a receiver that receives signals from the RFID devices.

11. The system of claim 10, wherein the controller demodulates signals received with the receiver.

12. The system of claim 7, wherein the signals are amplitude modulated.

13. The system of claim 7, further comprising:

an RFID device having a minimum modulation depth that is stored in the controller.

14. The system of claim 7, wherein the minimum modulation depth of at least one of the groups of RFID devices is between 39% and 54%.

15. The system of claim 7, wherein the signals have a carrier frequency between 30 and 300 KHz.

16. The system of claim 7, wherein the signals have a carrier frequency between 3 and 30 MHz.

17. The system of claim 7, wherein the signals have a carrier frequency between 300 MHz and 3 GHz.