Method and system for acquisition of a time stamped signal

• US 6,704,300 B1
• Filed: 08/16/1999
• Issued: 03/09/2004
• Est. Priority Date: 08/16/1999
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Chen, Xixian, Zhang, Song, Wu, Shiquan
• Primary Examiner(s): Ton, Dang
• Assistant Examiner(s): Duong, Frank
• Application Number:
  US09/374,000
• Time in Patent Office: 1,667 Days
• Field of Search: 370/509, 370/512, 370/503, 370/321, 370/324, 370/328, 370/350, 375/326, 375/343, 455/456, 342/357.01, 342/450
• US Class Current: 370/350
• CPC Class Codes: G01S 5/12 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial
• CPC Class Codes: H04J 3/0697 Synchronisation in a packet node
• CPC Class Codes: H04L 7/042 Detectors therefor, e.g. correlators, state machines digital correlators in general G06F17/15

Abstract

The invention is directed to a method and system for acquisition of a time stamped signal burst while preserving timing information. A system for acquisition of a time stamped signal burst while preserving timing information. The system includes a first framer, an offset frequency compensator and a second framer. The first framer is for framing a buffered signal burst using least mean squares tuning to produce a first time stamp. The offset frequency compensator is for substantially removing a frequency offset from the first time stamp to produce a rough signal burst. The second framer is for framing the rough signal burst using least mean squares tuning to produce a fine signal burst arid a second time stamp, the second time stamp being more reliable than the first time stamp. A method system or acquisition of a time stamped signal burst while preserving timing information including the steps of framing using LMS and compensating for frequency offset. An advantage of the invention is increased reliability of the time stamp of the acquired signal burst.

Claims

1. A system for acquisition of a time stamped signal burst while preserving timing information, the system comprising:

a. a first framer for framing a buffered signal burst using least mean squares tuning to produce a first time stamp;

b. an offset frequency compensator for substantially removing a frequency offset from the first time stamp to produce a rough signal burst; and

c. a second framer for framing the rough signal burst using least mean squares tuning to produce a fine signal burst and a second time stamp, the second time stamp being more reliable than the first time stamp.

2. The system recited in claim 1 wherein first framer also frames the fine signal burst using least mean squares tuning to produce the first time stamp.

3. The system recited in claim 1 wherein the first framer comprises:

a. a correlator for correlating the buffered signal burst using a SYNC word to produce a correlator output signal;

b. a peak position detector for detecting the peak position of the correlator output and producing a peak position signal; and

c. a least mean squares tuner for determining first time stamp using a least mean squares algorithm.

4. The system recited in claim 1, wherein the second framer includes:

a correlator for correlating the rough signal burst using a SYNC word to produce a correlator output signal;

a peak position detector for detecting the peak position of the correlator output and producing a peak position signal; and

a least mean squares tuner for determining the second time stamp using a least mean squares algorithm.

5. The system recited in claim 1 further comprising a time delay estimator for providing an intra-symbol delay estimate based on the output of the second framer.

6. The system recited in claim 5 wherein a module for combining the intra-symbol delay estimate with the second time stamp to form a final time of arrival (TOA) estimate.

7. A method of acquiring a time stamped signal burst while preserving timing information, the method comprising steps of:

a. framing a buffered signal burst using least mean squares tuning to produce a first time stamp;

b. substantially removing a frequency offset from the first time stamp to produce a rough signal burst; and

c. framing the rough signal burst using least mean squares tuning to produce a fine signal burst and a second time stamp, the second time stamp being more reliable than the first time stamp.

8. The method recited in claim 7, further comprising a step of framing the fine signal burst using least mean squares tuning to produce the first time stamp.

9. The method recited in claim 7, wherein the buffered signal burst framing step includes steps of:

a. correlating the buffered signal burst using a SYNC word to produce a correlator output signal;

b. detecting the peak position of the correlator output signal and producing a peak position signal; and

c. determining a first time stamp using a least mean squares algorithm.

10. The method recited in claim 7, wherein the rough signal burst framing step includes the steps of:

correlating the rough signal burst using a SYNC word to produce a correlator output signal;

detecting the peak position of the correlator output and producing a peak position signal; and

determining the second time stamp using a least mean squares algorithm.

11. The method recited in claim 7 further comprising the step of providing an intra-symbol delay estimate based on the result of the rough signal burst framing step.

12. The method recited in claim 11 further comprising the step of combining the intra-symbol delay estimate with the second time stamp to form a final time of arrival (TOA) estimate.

13. A system for acquisition of a time stamped signal burst while preserving timing information, the system comprising:

a framer for locating a signal burst using a least mean square;

an offset frequency compensator for substantially removing a frequency offset from the signal burst;

a clock phase estimator for estimating a sampling phase of an open-eye-sample sequence;

a module for processing the signal burst and the sample phase to provide raw data burst containing time delay information and the open-eye-sample sequence which is derived from the raw data burst; and

a fine adjustment module for providing framed raw data burst and the time stamp of its starting position using the open-eye-sample sequence.

14. The system recited in claim 13, wherein the processing module includes a module for aligning the starting position of the raw data burst with the starting position of the open-eye-sample sequence and an interpolator for producing the open-eye-sample sequence from the raw data burst.

15. The system recited in claim 14, wherein the processing module further includes a denolsing module for denoising the open-eye-sample sequence.

16. The system recited in claim 13, wherein the fine adjustment module includes a module for finding the starting position of the open-eye-sample sequence and a module for identifying the starting position of the raw data burst.

17. The system recited in claim 13, wherein the framer includes:

a correlator for correlating the signal burst using a SYNC word to produce a correlator output signal;

a peak position detector for detecting the peak position of the correlator output and producing a peak position signal; and

a least mean squares tuner for determining a time stamp of a staring position of the signal burst using a least mean squares algorithm.

18. The system recited in claim 13, wherein the fine adjustment module includes:

a correlator for correlating the open-eye-sample sequence using a SYNC word to produce a correlator output signal;

a peak position detector for detecting the peak position of the correlator output and producing a peak position signal; and

a module for determining the time stamp of the starting position of the raw data burst using the peak position signal.

19. The system recited in claim 13 further comprising a time delay estimator for providing an intra-symbol delay estimate based on the framed raw data burst.

20. The system recited in claim 19 further comprising a module for combining the intra-symbol delay estimate with the time stamp to form a final time of arrival (TOA) estimate.

21. A method of acquisition of a time stamped signal burst while preserving timing information, the system comprising:

locating a signal burst using a least mean square;

substantlally removing a frequency offset from the signal burst;

estimating a sampling phase of an open-eye-sample sequence;

processing the signal burst and the sample phase to provide raw data burst containing time delay information and the open-eye-sample sequence which is derived from the raw data burst; and

performing a fine adjustment to provide framed raw data burst and the time stamp of its starting position using the open-eye-sample sequence.

22. The method recited in claim 21, wherein the fine adjustment steps includes the steps of:

correlating the open-eye-sample sequence using a SYNC word to produce a correlator output signal;

detecting the peak position of the correlator output and producing a peak position signal; and

determining the time stamp of the starting position of the raw data burst using the peak position signal.

23. The method recited in claim 21, further comprising the step of providing an intra-symbol delay estimate based on the framed raw data burst.

24. The method recited in claim 23 further comprising the step of combining the intra-symbol delay estimate with the time stamp to form a final time of arrival (TOA) estimate.

25. The method recited in claim 21, wherein the processing step includes the step of aligning the starting position of the raw data burst with the starting position of the open-eye-sample sequence and the step of performing interpolation to produce the open-eye-sample sequence from the raw data burst.

26. The method recited in claim 25, wherein the processing step further includes the steps of denoising the open-eye-sample sequence.

27. The method recited in claim 21, wherein the fine adjustment performing step includes the step of finding the starting position of the open-eye-sample sequence and the step of identifying the starting position of the raw data burst.

28. The method recited in claim 21, wherein the locating step includes the steps of:

correlating the signal burst using a SYNC word to produce a correlator output signal;

detecting the peak position of the correlator output and producing a peak position signal; and

determining a time stamp of a staring position of the signal burst using a least mean squares algorithm.