RFID device time synchronization from a public source

1. A radio frequency identification (RFID) device comprising:

an antenna tuned to receive a radio frequency (RF) time-code signal from a public source;

a receiving circuit linked to the antenna, wherein the receiving circuit is configured to convert the received RF time-code signal into a digital time-code bit stream;

a controller circuit linked to the receiving circuit, wherein the controller circuit is configured to decode the digital time-code bit stream;

an internal clock linked to the controller circuit, wherein a time maintained by the internal clock is updated based on the decoded time-code bit stream received from the controller circuit;

a microcontroller linked to the receiving circuit;

a memory linked to the microcontroller; and

a battery linked to and powering the receiving circuit, controller circuit, internal clock, microcontroller and memory.

2. The RFID device of claim 1 wherein the public source is a National institute of Standards and Technology (NIST) radio station WWVB.

3. The RFID device of claim 1 wherein the public source is a Global Positioning System (GPS) source.

4. A radio frequency identification (RFID) device comprising:

a Global Positioning System (GPS) receiver configured to receive a radio frequency (RF) time-code signal from a Global Navigation Satellite System (GNSS), wherein the GPS receiver is configured to convert the received RF time-code signal into a digital time-code bit stream;

a controller circuit linked to the GPS receiver, wherein the controller circuit is configured to decode the digital time-code bit stream;

an internal clock linked to the controller circuit, wherein a time maintained by the internal clock is updated based on the decoded time-code bit stream received from the controller circuit;

a microcontroller linked to the receiving circuit;

a memory linked to the microcontroller; and

a battery linked to and powering the GPS circuit, controller circuit, internal clock, microcontroller and memory.

5. A radio frequency identification (RFID) device comprising:

a LORAN-C receiver configured to receive a radio frequency (RF) time-code signal, wherein the LORAN-C receiver is configured to convert the received RF time-code signal into a digital time-code bit stream;

a controller circuit linked to the LORAN-C receiver, wherein the controller circuit is configured to decode the digital time-code bit stream;

an internal clock linked to the controller circuit, wherein a time maintained by the internal clock is updated based on the decoded time-bit stream received from the controller circuit;

a microcontroller linked to the receiving circuit;

a memory linked to the microcontroller; and

a battery linked to and powering the LORAN-C circuit, controller circuit, internal clock, microcontroller and memory.

6. A radio frequency identification (RFID) device comprising:

an antenna tuned to receive a radio frequency (RF) time-code signal from a public source;

a receiving circuit linked to the antenna, wherein the receiving circuit is configured to convert the received RF time-code signal into a digital time-code bit stream;

a controller circuit linked to the receiving circuit, wherein the controller circuit is configured to decode the digital time-code bit stream;

an internal clock linked to the controller circuit, wherein a time maintained by the internal clock is updated based on the decoded time-code bit stream received from the controller circuit;

a microcontroller linked to the receiving circuit; and

a memory linked to the microcontroller.

7. The RFID device of claim 6 wherein the public source is a National institute of Standards and Technology (NIST) radio station WWVB.

8. The RFID device of claim 6 wherein the public source is a terrestrial radio clock source.

9. The RFID device of claim 6 wherein the public source is a Global Positioning System (GPS) source.

10. A method comprising:

in a radio frequency identification (RFID) device, receiving a radio frequency (RF) time-code signal from a public source;

converting the received RF time-code signal into a digital time-code bit stream;

decoding the digital time-code bit stream; and

updating a time maintained by an internal clock based on the decoded time-code bit stream.

11. The method of claim 10 wherein the public source is a National institute of Standards and Technology (NIST) radio station WWVB.

12. The method of claim 10 wherein the public source is a terrestrial source.

13. The method of claim 10 wherein the public source is a Global Positioning System (UPS) source.

14. A system comprising:

a radio frequency identification (RFID) device comprising:

an antenna tuned to receive a radio frequency (RF) time-code signal from a public source,

a receiving circuit linked to the antenna, wherein the receiving circuit is configured to convert the received RF time-code signal into a digital time-code bit stream,

a controller circuit linked to the receiving circuit, wherein the controller circuit is configured to decode the digital time-code bit stream, and

an internal clock linked to the controller circuit, wherein a time maintained by the internal clock is updated based on the decoded time-code bit stream received from the controller circuit;

a RFID interrogator configured to interrogate the RFID device and receive in response an RFID identification and a time stamp, wherein the time stamp corresponds to the time maintained by the internal clock; and

a subsystem linked to the RFID interrogator, wherein the subsystem is configured to store the RFID identification and time stamp received from the RFID interrogator.

15. The system of claim 14 wherein the public source is a National institute of Standards and Technology (NIST) radio station WWVB.

16. The system of claim 14 wherein the public source is a terrestrial source.

17. The system of claim 14 wherein the public source is a Global Positioning System (GPS) source.