RF device comparing DAC output to incoming signal for selectively performing an action

• US 8,098,159 B2
• Filed: 06/09/2006
• Issued: 01/17/2012
• Est. Priority Date: 06/09/2006
• Status: Active Grant

• Current Assignee: Zest Labs, Inc.
• Original Assignee: Intelleflex Corporation
• Inventors: Batra, Naresh, Nandu, Heena
• Primary Examiner(s): Lu, Shirley
• Application Number:
  US11/423,411
• Publication Number:
  US 20070285237A1
• Time in Patent Office: 2,048 Days
• Field of Search: 340/572.1, 340/693.3, 340/10.1
• US Class Current: 340/572.1
• CPC Class Codes: G06K 19/0716 at least one of the integrated circuit chips comprising a sensor or an interface to a sensor
• CPC Class Codes: G06K 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card

Abstract

A Radio Frequency (RF) device such as a Radio Frequency Identification (RFID) tag according to one embodiment includes a Digital to Analog Converter (DAC) for generating a reference signal based on a stored digital comparison criteria value, and a mechanism for comparing an incoming signal to the reference signal. The device performs an action such as backscattering based on the comparison. Additional systems and methods are also disclosed.

Claims

1. A Radio Frequency Identification (RFID) tag, comprising:

a Digital to Analog Converter (DAC) for generating a reference signal based on a stored digital comparison criteria value, wherein the digital comparison criteria value is remotely changeable; and

a mechanism for comparing an incoming interrogator signal to the reference signal,

wherein the tag performs an action based on the comparison,

wherein the raw incoming interrogator signal is compared to the reference signal.

2. The tag as recited in claim 1, wherein the action performed by the tag is backscattering if the incoming interrogator signal is at least as great as the reference signal.

3. The tag as recited in claim 1, wherein the incoming interrogator signal has been processed prior to being compared to the reference signal.

4. The tag as recited in claim 1, wherein the DAC stores the digital comparison criteria value.

5. The tag as recited in claim 1, further comprising memory for storing the digital comparison criteria value.

6. The tag as recited in claim 1, wherein authorization is required prior to allowing a change of the digital comparison criteria value.

7. The tag as recited in claim 1, wherein the digital comparison criteria value is changed if a code is received and the received code matches a code stored on the tag, and the digital comparison criteria value is not changed if the received code does not match a code stored on the tag.

8. The tag as recited in claim 7, wherein the received code is a master code.

9. The tag as recited in claim 1, wherein more than one digital comparison criteria value is stored.

10. The tag as recited in claim 1, wherein the digital comparison criteria value has been selected based at least in part on an environmental condition.

11. The tag as recited in claim 1, wherein the digital comparison criteria value has been selected based at least in part on a backscatter response from a calibration device.

12. A Radio Frequency Identification (RFID) system, comprising:

a plurality of RFID tags as recited in claim 1; and

an RFID interrogator in communication with the RFID tags.

13. A method for selectively responding to an interrogator, comprising:

receiving a signal from an interrogator;

comparing the signal from the interrogator to a reference signal generated by a Digital to Analog Converter (DAC) based on a digital comparison criteria value, wherein more than one digital comparison criteria value used by the DAC to generate the reference signal is stored locally;

responding to the interrogator signal if the interrogator signal is greater than the reference signal; and

not responding to the interrogator signal if the interrogator signal is smaller than the reference signal.

14. The method as recited in claim 13, wherein the raw incoming interrogator signal is compared to the reference signal.

15. The method as recited in claim 13, wherein the incoming interrogator signal has been processed prior to being compared to the reference signal.

16. The method as recited in claim 13, wherein the DAC stores a digital comparison criteria value used by the DAC to generate the reference signal.

17. The method as recited in claim 13, wherein a memory stores a digital comparison criteria value used by the DAC to generate the reference signal.

18. The method as recited in claim 13, wherein a digital comparison criteria value used by the DAC to generate the reference signal is changeable.

19. The method as recited in claim 18, wherein authorization is required prior to allowing a change of the digital comparison criteria value.

20. The method as recited in claim 18, wherein a digital comparison criteria value used by the DAC to generate the reference signal is changed if a code is received and the received code matches a code stored on the tag, and the digital comparison criteria value is not changed if the received code does not match a code stored on the tag.

21. The method as recited in claim 13, wherein a digital comparison criteria value used by the DAC to generate the reference signal has been selected based at least in part on an environmental condition.

22. The method as recited in claim 13, wherein a digital comparison criteria value used by the DAC to generate the reference signal has been selected based at least in part on a backscatter response from a calibration device.

23. A Radio Frequency Identification (RFID) system, comprising:

a plurality of RFID tags performing the method recited in claim 13; and

an RFID interrogator in communication with the RFID tags.

24. A Radio Frequency (RF) device, comprising:

a Digital to Analog Converter (DAC) for generating a reference signal based on a stored digital comparison criteria value,

wherein more than one digital comparison criteria value used by the DAC to generate the reference signal is stored,

wherein the digital comparison criteria value is remotely changeable,

wherein the digital comparison criteria value is stored if a code is remotely received and the remotely received code matches a code stored on the tag, and the digital comparison criteria value is not stored if the remotely received code does not match a code stored on the tag; and

a mechanism for comparing an incoming signal to the reference signal,

wherein the device performs an action based on the comparison.