End of modulation detection

• US 8,391,824 B2
• Filed: 06/21/2011
• Issued: 03/05/2013
• Est. Priority Date: 07/01/2010
• Status: Active Grant

• Current Assignee: Zest Labs, Inc.
• Original Assignee: Intelleflex Corporation
• Inventors: Kawaguchi, Dean
• Primary Examiner(s): Nguyen, Duc M
• Application Number:
  US13/165,745
• Publication Number:
  US 20120003951A1
• Time in Patent Office: 623 Days
• Field of Search: 455/226.1, 455/228, 455/334, 455/337, 455/41.1, 455/41.2, 375/324, 340/10.1, 340/572.4
• US Class Current: 455/334
• 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 detecting an end of modulation in a backscattered radio frequency signal according to one embodiment includes generating a fast average of a magnitude or power of an incoming signal; generating a slow average of the magnitude or power of the incoming signal; determining an end of modulation based on a relationship between the fast and slow averages; and outputting an end of modulation signal upon determining the end of modulation. A system for detecting an end of modulation in a backscattered radio frequency signal according to one embodiment includes a window integrator for generating a fast moving average of a magnitude or power of an incoming signal; a leaky integrator for generating a slow moving average of the magnitude or power of the incoming signal; logic for determining an end of modulation when the fast moving average crosses below the slow moving average; and logic for outputting an end of modulation signal. Additional systems and methods are also presented.

Claims

1. A method for detecting an end of modulation in a backscattered radio frequency signal, the method comprising:

generating a fast average of a magnitude or power of an incoming signal;

generating a slow average of the magnitude or power of the incoming signal;

determining an end of modulation based on a relationship between the fast and slow averages; and

outputting an end of modulation signal upon determining the end of modulation.

2. The method of claim 1, wherein the incoming signal is a correlator magnitude signal output by a correlator module.

3. The method of claim 1, wherein the fast and slow averages are moving averages, wherein the end of modulation is determined upon the fast moving average crossing below the slow moving average.

4. The method of claim 1, wherein a window integrator is used to generate the fast average.

5. The method of claim 1, wherein a leaky integrator is used to generate the slow average.

6. A system for detecting an end of modulation in a backscattered radio frequency signal, comprising:

logic for generating a fast average of a magnitude or power of an incoming signal;

logic for generating a slow average of the magnitude or power of the incoming signal;

logic for determining an end of modulation based on a relationship between the fast and slow averages; and

logic for outputting an end of modulation signal upon determining the end of modulation.

7. The system of claim 6, wherein the incoming signal is a correlator magnitude signal output by a correlator module.

8. The system of claim 6, wherein the fast and slow averages are moving averages, wherein the end of modulation is determined upon the fast moving average crossing below the slow moving average.

9. The system of claim 6, wherein a window integrator is used to generate the fast average.

10. The system of claim 6, wherein a leaky integrator is used to generate the slow average.

11. The system of claim 6, further comprising at least one antenna for receiving the radio frequency signal.

12. A system for detecting an end of modulation in a backscattered radio frequency signal, comprising:

a window integrator for generating a fast moving average of a magnitude or power of an incoming signal;

a leaky integrator for generating a slow moving average of the magnitude or power of the incoming signal;

logic for determining an end of modulation when the fast moving average crosses below the slow moving average; and

logic for outputting an end of modulation signal.

13. The system of claim 12, wherein the incoming signal is a correlator magnitude signal output by a correlator module.

14. The system of claim 12, further comprising at least one antenna for receiving the radio frequency signal.