ADJUSTING PARAMETERS ASSOCIATED WITH LEAKAGE SIGNALS

• US 20080041953A1
• Filed: 04/27/2007
• Published: 02/21/2008
• Est. Priority Date: 04/27/2006
• Status: Active Grant

• Current Assignee: Neology Incorporated (OEP Technologie BV)
• Original Assignee: Sirit Technologies, Inc.
• Inventors: Repke, Joseph P., Frederick, Thomas J.
• Granted Patent: US 8,226,003 B2
• Time in Patent Office: Days
• US Class Current: 235/451
• 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
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver

Abstract

The present disclosure includes a system and method for adjusting parameters associated with leakage signals. In some implementations, an RFID reader includes an RF antenna, a transmitter section, a receiver section, a control module and a cancellation noise reduction (CNR) section. The transmitter section is coupled to the RF antenna and operable to generate a transmit signal to be transmitted by the RF antenna. The receiver section is coupled to the RF antenna and operable to receive a receive signal from the RF antenna. In addition, the receiver section further includes a de-rotation module and a control module. The de-rotation module is operable to de-rotate, by θ, an in-phase signal and quadrature signal associated with the leakage signal. The control module is operable to generate control signals used to produce a signal for reducing the leakage signal in a receive path of the reader. The CNR section is operable to subtract from the reduction signal from the leakage signal.

Claims

1. An RFID reader comprising:

a RF antenna;

a transmitter section coupled to the RF antenna and operable to generate a transmit signal to be transmitted by the RF antenna;

a receiver section coupled to the RF antenna and operable to receive a receive signal from the RF antenna, the receiver section further comprising;

a de-rotation module operable to de-rotate, by θ

, an in-phase signal and quadrature signal associated with the leakage signal; and

a control module operable to generate control signals used to produce a signal for reducing the leakage signal in a receive path of the reader; and

a carrier noise reduction (CNR) section operable to subtract the reduction signal from the leakage signal.

2. The RFID reader of claim 1, further comprising a DC offset module operable to subtract DC offsets from the in-phase signal and the quadrature signal associated with the leakage signal.

3. The RFID reader of claim 2, wherein the control signals for the reduction signal are determined after the in-phase signal and quadrature signal associated with the leakage signal are de-rotated and the DC offsets are subtracted.

4. The RFID reader of claim 2, further comprising a DC offset estimation module operable to determine a plurality of samples of the DC offsets of the in-phase signal and the quadrature signal associated with the leakage signal and determine the estimated DC offsets based, at least, in part, on the average of the samples.

5. The RFID reader of claim 2, wherein the DC offsets are subtracted from the in-phase signal and the quadrature signal after downconverting the RF to the in-phase signal and the quadrature signal.

6. The RFID reader of claim 1, further comprising a phase estimation module operable to determine a plurality of samples of the phase offset of the in-phase signal and the quadrature signal associated with the leakage signal and determine the de-rotation angle based, at least in part, on the average of the samples.

7. The RFID reader of claim 1, wherein the leakage signal is reduced by over 20 dB.

8. The RFID reader of claim 1, wherein the de-rotation angle is based, at least in part, on a phase offset associated with the in-phase signal and a phase offset associated with the quadrature signal.

9. The RFID reader of claim 1, further comprising a quadrature modulator operable to receive the control signals and a portion of a transmission signal to generate the reduction signal.

10. The RFID reader of claim 1, wherein the in-phase signal and the quadrature signal are de-rotated after downconverting the RF signal to the in-phase signal and the quadrature signal.

11. A method, comprising:

transmitting an RF signal in an interrogation zone;

downconverting an RF signal on a receive path to an in-phase and a quadrature signal;

determining a phase-shift offset associated with leakage signals from the transmitted RF signal;

de-rotating the in-phase signal and the quadrature signal using the determine phase-shift offset;

generating control signals used to produce a signal for reducing the leakage signal in the receive path based, at least in part, on the de-rotated in-phase signal and the de-rotated quadrature signal; and

subtracting the reduction signal from the leakage signal.

12. The method of claim 11, further comprising:

determining DC offsets of the in-phase signal and the quadrature signal; and

subtracting the DC offsets from the in-phase signal and the quadrature signal associated with the leakage signal.

13. The method of claim 12, wherein the control signals for the reduction signal are determined after the in-phase signal and quadrature signal associated with the leakage signal are de-rotated and the DC offsets are subtracted.

14. The method of claim 12, wherein the DC offsets are determined based, at least in part, on a plurality of samples of the DC offsets of the in-phase signal and the quadrature signal associated with the leakage signal.

15. The method of claim 12, wherein the DC offsets are subtracted from the in-phase signal and the quadrature signal after downconverting the RF signal to the in-phase signal and the quadrature signal.

16. The method of claim 11, wherein the phase-shift offset is determined, based at least in part, on a plurality of samples of the phase-shift offset of the in-phase signal and the quadrature signal associated with the leakage signal.

17. The method of claim 11, wherein the leakage signal is reduced by 20 dB or greater.

18. The method of claim 11, wherein the de-rotation angle is based, at least in part, on a phase-shift offset associated with both the in-phase signal and a phase offset associated with the quadrature signal.

19. The method of claim 11, further comprising generating the reduction signal based, at least in part, on a portion of the transmission signal and the control signals.

20. The method of claim 11, wherein the in-phase signal and the quadrature signal are de-rotated after downconverting the RF signal to the in-phase signal and the quadrature signal.