Half bit correlator combining for data demodulation

• US 9,183,418 B2
• Filed: 06/21/2011
• Issued: 11/10/2015
• Est. Priority Date: 07/01/2010
• Status: Active Grant

• Current Assignee: Zest Labs, Inc.
• Original Assignee: Intelleflex Corporation
• Inventors: Kawaguchi, Dean
• Primary Examiner(s): Ahn, Sam K
• Assistant Examiner(s): Ali, Shawkat M
• Application Number:
  US13/165,734
• Publication Number:
  US 20120002763A1
• Time in Patent Office: 1,603 Days
• Field of Search: 329/304, 329/313, 329/319, 329/321, 329/349, 370/328, 370/338, 370/503, 375/148, 375/150, 375/219, 375/227, 375/239, 375/316, 375/324, 375/343, 375/345, 375/346, 375/362, 375/375, 455/63.1, 455/323, 455/337, 455/445, 455/502, 340/10.1, 340/10.4, 340/572.4, 708/404, 708/422, 708/813
• US Class Current: 1/1
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• 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: H04Q 2213/13095 PIN / Access code, authentication

Abstract

A method for demodulating a data signal according to one embodiment includes processing baseband signals using multiple complex correlators each having a half-Tbit length; summing outputs of the complex correlators for a first data state; and differencing outputs of the complex correlators for a second data state. A system for demodulating a data signal according to one embodiment includes a correlator module having logic for: processing baseband signals using multiple complex correlators each having a half-Tbit length; summing outputs of the complex correlators for a first data state; and differencing outputs of the complex correlators for a second data state. Additional systems and methods are also presented.

Claims

1. A method for demodulating a data signal, the method comprising:

processing baseband signals using multiple complex correlators each having a half-Tbit length, wherein Tbit is the length of data bit;

summing outputs of the multiple complex correlators for a first data state; and

differencing outputs of the multiple complex correlators for a second data state.

2. The method of claim 1, wherein each of the complex correlators includes a delayed integrator and a nondelayed integrator.

3. The method of claim 1, wherein the summed outputs are kept separate until after outputs of complex-to-magnitude modules.

4. The method of claim 1, wherein each of the complex correlators includes a series of windowed integrators that are configurable for different lengths.

5. The method of claim 1, further comprising generating a correlator magnitude signal, and further comprising using the correlator magnitude signal to determine an end of a signal modulation.

6. The method of claim 1, further comprising generating a correlator magnitude signal, and further comprising using the correlator magnitude signal to adjust an automatic gain control setting.

7. The method of claim 1, further comprising generating a correlator magnitude signal, and further comprising using the correlator magnitude signal to derive a received signal strength indicator estimate.

8. The method of claim 1, wherein the baseband signals are derived from a Miller modulated signal or a signal having bi-phase-space (FM0) encoding.

9. The method of claim 1, wherein the first data state corresponds to a data 1, wherein the second data state corresponds to a data 0.

10. The method of claim 1, wherein the first data state corresponds to a data 0, wherein the second data state corresponds to a data 1.

11. A system for demodulating a data signal, the system comprising:

a correlator configured to;

process baseband signals using multiple complex correlators each having a half-Tbit length, wherein Tbit is the length of data bit;

sum outputs of the multiple complex correlators for a first data state; and

difference outputs of the multiple complex correlators for a second data state.

12. The system of claim 11, wherein each of the complex correlators includes a delayed integrator and a nondelayed integrator.

13. The system of claim 11, wherein the summed outputs are kept separate until after outputs of complex-to-magnitude modules.

14. The system of claim 11, wherein each of the complex correlators includes a series of windowed integrators that are configurable for different lengths.

15. The system of claim 11, further comprising generating a correlator magnitude signal, and further comprising logic for using the correlator magnitude signal to determine an end of a signal modulation.

16. The system of claim 11, wherein the baseband signals are derived from a Miller modulated signal or a signal having FM0 encoding.

17. The system of claim 11, further comprising at least one antenna for receiving a radio frequency signal from which the baseband signals are derived.

18. The system of claim 11, further comprising logic for generating a correlator magnitude signal, and further comprising logic for using the correlator magnitude signal to adjust an automatic gain control setting.

19. The system of claim 11, further comprising logic for generating a correlator magnitude signal, and further comprising logic for using the correlator magnitude signal to derive a received signal strength indicator estimate.

20. The system of claim 11, wherein the first data state corresponds to a data 1, wherein the second data state corresponds to a data 0.

21. The system of claim 11, wherein the first data state corresponds to a data 0, wherein the second data state corresponds to a data 1.