System and method of reading RFID tags at high speeds

• US 8,179,260 B2
• Filed: 01/29/2009
• Issued: 05/15/2012
• Est. Priority Date: 01/29/2009
• Status: Active Grant

• Current Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Original Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Inventors: Pillai, Vijay
• Primary Examiner(s): Bugg, George
• Assistant Examiner(s): MCNALLY, KERRI L
• Application Number:
  US12/361,749
• Publication Number:
  US 20100188225A1
• Time in Patent Office: 1,202 Days
• Field of Search: 340/572.1
• US Class Current: 340/572.1
• CPC Class Codes: G06K 19/00 Record carriers for use with machines and with at least a part designed to carry digital markings
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer

Abstract

Processing a transponder signal received from a transponder may include providing a first signal that is in-phase with the transponder signal and a second that is off-phase with the first signal. A first transformed signal is generated using the first signal, where the first transformed signal has a first characteristic equal to the first characteristic of the first signal and a second characteristic different from the second characteristic of the first signal. A second transformed signal is generated using the second signal, where the second transformed signal has a first characteristic equal to the first characteristic of the second signal and a second characteristic different from the second characteristic of the second signal. Information incorporated in the transponder signal is obtained using a combination of the first transformed signal and the second transformed signal.

Claims

1. A method of processing a transponder signal received from a transponder to identify the transponder, the method comprising:

providing a first signal from the transponder signal, the first signal having a first and a second characteristics;

providing a second signal that is different in phase with respect to the first signal, the second signal having a first and a second characteristics;

generating a first transformed signal by altering the first characteristic of the first signal and retaining the second characteristic of the first signal to provide the first transformed signal;

the first transformed signal comprising squaring a value of the first signal and retaining a sign of the first signal to provide the first transformed signal;

generating a second transformed signal by altering the first characteristic of the second signal and retaining the second characteristic of the second signal to provide the second transformed signal;

the second transformed signal comprising squaring a value of the second signal and retaining a sign of the second signal to provide the second transformed signal; and

obtaining information incorporated in the transponder signal using a combination of the first transformed signal and the second transformed signal.

2. The method of claim 1 wherein obtaining information incorporated in the transponder signal using a combination of the first transformed signal and the second transformed signal comprises summing the first transformed signal and the second transformed signal to provide a resultant signal, and decoding the resultant signal to provide information incorporated in the transponder signal.

3. The method of claim 1 wherein obtaining information incorporated in the transponder signal using a combination of the first transformed signal and the second transformed signal comprises obtaining identification information associated with the transponder using a combination of the first transformed signal and the second transformed signal.

4. The method of claim 1 wherein providing a second signal that is different in phase with respect to the first signal comprises phase-shifting the first signal by 90 degrees to provide the second signal.

5. The method of claim 1 wherein providing a first signal from the transponder signal comprises receiving the transponder signal from the transponder that is moving at a relative speed of at least 15 miles per hour to provide the first signal.

6. A method of a transponder reader, the method comprising:

receiving a first signal from the transponder;

receiving a second signal from the transponder;

the second signal differing from the first signal in phase;

generating a first transformed signal from the first signal and a second transformed signal from the second signal, the first transformed signal being greater than the first signal in amplitude and having the same sign as the first signal, the second transformed signal being greater than the second signal in amplitude and having the same sign as the second signal;

providing a resultant signal using the first transformed signal and the second transformed signal; and

decoding the resultant signal to provide information encoded in the received signal.

7. The method of claim 6 wherein the second signal comprises phase-shifting the first signal by a predetermined amount of degrees to provide the second signal.

8. The method of claim 6 wherein generating a first transformed signal from the first signal and a second transformed signal from the second signal comprises squaring the first signal and retaining the sign of the first signal to provide the first transformed signal, and computationally squaring the second signal and retaining the sign of the second signal to provide the second transformed signal.

9. The method of claim 6 wherein providing a resultant signal using the first transformed signal and the second transformed signal comprises combining the first transformed signal and the second transformed signal to provide the resultant signal.

10. The method of claim 6 wherein providing a resultant signal using the first transformed signal and the second transformed signal comprises summing the first transformed signal and the second transformed signal to provide the resultant signal.

11. The method of claim 6 wherein generating a first transformed signal from the first signal and a second transformed signal from the second signal comprises computationally calculating the first transformed signal from the first signal and the second transformed signal from the second signal.

12. The method of claim 6 wherein receiving the first signal from the transponder comprises receiving the first signal from the transponder that is moving at a relative speed of at least 15 miles per hour.

13. A communication system, comprising:

a first circuit to receive a wireless signal from a signal source and to provide a first signal and a second signal that differs from the first signal in phase using the wireless signal;

a second circuit to receive the first and the second signals and to generate a first transformed signal and a second transformed signal from the first signal and the second signal, respectively, the first transformed signal being greater than the first signal in amplitude and having the same sign as the first signal, the second transformed signal being greater than the second signal in amplitude and having the same sign as the second signal; and

a third circuit to receive the first and the second transformed signals and to derive information encoded in the wireless signal using the first and the second transformed signals.

14. The communication system of claim 13, further comprising:

a filter circuit to receive the first and the second signals from the first circuit and to filter out a respective portion of each of the first and the second signals before providing the filtered first and the filtered second signals to the second circuit.

15. The communication system of claim 14 wherein the filter circuit includes a first low-pass filter to low-pass filter the first signal and a second low-pass filter to low-pass filter the second signal.

16. The communication system of claim 13 wherein the second circuit generates the first transformed signal to have a value related to a squared value of the first signal and a sign of the first signal, and wherein the second circuit generates the second transformed signal to have a value related to a squared value of the second signal and a sign of the second signal.

17. The communication system of claim 13 wherein the third circuit combines the first and the second transformed signals to provide a combined signal from which the information encoded in the wireless signal is derived.

18. The communication system of claim 17 wherein the third circuit sums the first and the second transformed signals to provide the combined signal.

19. The communication system of claim 13 wherein the first, the second, and the third circuits are parts of a processor.

20. The communication system of claim 13 wherein the wireless signal is received from the signal source that has a speed of at least 15 miles per hour relative to the first circuit.

21. A radio frequency identification (RFID) system, comprising:

at least one antenna to receive a transponder signal; and

a processing logic coupled to the at least one antenna, the processing logic to provide a first signal and a second signal having a phase different from a phase of the first signal based on the transponder signal and to transform the first and the second signals into a first transformed signal and a second transformed signal, respectively, where the first transformed signal is a multiple of the first signal and has the same sign as the first signal, and where the second transformed signal is a multiple of the second signal and has the same sign as the second signal, the processing logic to combine the first and the second transformed signals to determine information encoded in the transponder signal.

22. The RFID system of claim 21 wherein the processing logic squares the value of the first signal and retains the sign of the first signal to provide the first transformed signal, and wherein the processing logic squares the value of the second signal and retains the sign of the second signal to provide the second transformed signal.

23. The RFID system of claim 21 wherein the processing logic sums the first and the second transformed signal to provide a combined signal, and wherein the processing logic decodes the combined signal to determine the information encoded in the transponder signal.

24. The RFID system of claim 21, further comprising:

a transmitter that transmits a query signal to an RFID transponder which returns the transponder signal in response to receiving the query signal.

25. The RFID system of claim 21 wherein the processing logic comprises a processor.

26. The RFID system of claim 21 wherein the receiver receives the transponder signal from an RFID transponder moving at a speed of at least 15 mile per hour relative to the RFID system.

27. The RFID system of claim 21 wherein the phase of the first signal and the phase of the second signal are in quadrature.