Variable rate preamble detection using ratiometric methods

• US 8,723,651 B2
• Filed: 06/21/2011
• Issued: 05/13/2014
• Est. Priority Date: 07/01/2010
• Status: Active Grant

• Current Assignee: Zest Labs, Inc.
• Original Assignee: Intelleflex Corporation
• Inventors: Kawaguchi, Dean
• Primary Examiner(s): BEE, ANDREW W.
• Application Number:
  US13/165,739
• Publication Number:
  US 20120001732A1
• Time in Patent Office: 1,057 Days
• Field of Search: 340/10.1, 340/10.4, 375/239, 375/359, 375/360, 375/368
• US Class Current: 340/10.4
• 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 a pattern in a signal according to one embodiment includes determining a time between symbol transitions in a signal derived from a radio frequency signal; determining ratios of relational times between consecutive symbol transitions; and comparing a sequence of the ratios to a target pattern for determining whether the sequence corresponds to the target pattern. Such methodology may also be implemented as a system using logic for performing the various operations. Additional systems and methods are also presented.

Claims

1. A method for detecting a pattern in a signal, the method comprising:

determining a time between symbol transitions in a signal derived from a radio frequency signal;

determining ratios of relational times between consecutive symbol transitions; and

comparing a sequence of the ratios to a target pattern for determining whether the sequence corresponds to the target pattern.

2. The method of claim 1, wherein the method is performed without input from a clock recovery section.

3. The method of claim 1, wherein the target pattern corresponds to a preamble delimiter in a signal derived from a radio frequency signal.

4. The method of claim 1, wherein the comparing the sequence of the ratios to the target pattern includes assigning a value to each ratio based on the ratio falling within a range corresponding to the value, and comparing a resulting sequence of values to the target pattern.

5. The method of claim 4, wherein each ratio corresponds to more than one value.

6. The method of claim 5, wherein the target pattern includes a plurality of allowable values for each position in the sequence.

7. The method of claim 1, further comprising also determining a sign of each ratio based on a direction of associated symbol transitions.

8. The method of claim 1, further comprising outputting a detect signal upon determining that the sequence corresponds to the target pattern.

9. The method of claim 8, wherein the detect signal is used to indicate a time to jam set a clock section.

10. The method of claim 1, wherein the method is implemented in a radio frequency identification reader.

11. The method of claim 1, wherein the method is implemented in a radio frequency identification tag.

12. A system for detecting a pattern in a signal, the system comprising hardware configured with logic comprising:

logic for determining a time between symbol transitions in a signal derived from a radio frequency signal;

logic for determining ratios of relational times between consecutive symbol transitions; and

logic for comparing a sequence of the ratios to a target pattern for determining whether the sequence corresponds to the target pattern.

13. The system of claim 12, wherein the logic is configured to compare functions without input from a clock recovery section.

14. The system of claim 12, wherein the target pattern corresponds to a preamble delimiter in a signal derived from a radio frequency signal.

15. The system of claim 12, wherein the logic for comparing the sequence of the ratios to the target pattern includes logic for assigning a value to each ratio based on the ratio falling within a range corresponding to the value, and logic for comparing a resulting sequence of values to the target pattern.

16. The system of claim 15, wherein each ratio corresponds to more than one value.

17. The method of claim 16, wherein the target pattern includes a plurality of allowable values for each position in the sequence.

18. The system of claim 12, further comprising also determining a sign of each ratio based on a direction of associated symbol transitions.

19. The system of claim 12, further comprising outputting a detect signal upon determining that the sequence corresponds to the target pattern.

20. The system of claim 19, wherein the detect signal is used to indicate a time to jam set a clock section.

21. The system of claim 12, wherein the logic is implemented in a radio frequency identification reader.

22. The system of claim 12, wherein the logic is implemented in a radio frequency identification tag.

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