Variable rate preamble detection using ratiometric methods
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.
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.