System and method for timing correction for fast PN acquisition

• US 7,430,263 B1
• Filed: 05/06/2004
• Issued: 09/30/2008
• Est. Priority Date: 05/06/2004
• Status: Active Grant

• Current Assignee: L-3 Communications Corporation (L3Harris Technologies, Inc.)
• Original Assignee: L-3 Communications Corporation (L3Harris Technologies, Inc.)
• Inventors: Timothy, LaMar K., Wilson, Michael L., Batzer, Patricia F.
• Primary Examiner(s): Liu; Shuwang
• Assistant Examiner(s): Neff; Michael R
• Application Number:
  US10/840,521
• Time in Patent Office: 1,608 Days
• Field of Search: 375/367, 370/515
• US Class Current: 375/367
• CPC Class Codes: H04L 7/042 Detectors therefor, e.g. correlators, state machines digital correlators in general G06F17/15

Abstract

A timing correction system for fast PN acquisition is provided. The system includes a signal sampler for testing any incoming signal and a real-time clocker coupled to the signal sampler. A parallel correlator is coupled to the real-time clocker for searching for a PN sequence and a burst detector is coupled to the parallel correlator. A chip timing corrector is coupled to the burst detector and a processor is coupled to the chip timing corrector for determining signal timing.

Claims

1. A method for timing correction for fast PN acquisition, the method comprising:

measuring a first set of measured points, wherein the first set of measured points correspond to a first set of measured correlation samples;

determining a set of ideal points;

comparing the first set of measured points against the set of ideal points, wherein comparing the first set of measured points against the set of ideal points further comprises;

measuring a plurality of correlation samples;

assigning a first discrete time to the plurality of measured correlation samples;

assigning a time shift in units of samples;

determining a theoretical set of discrete magnitudes;

determining a correlation function;

determining where the correlation function equals zero;

zeroing the theoretical set of discrete magnitudes where the correlation function equation equals zero;

determining a difference between the theoretical set of discrete magnitudes and measured plurality of correlation samples;

squaring the difference;

summing the squared difference; and

determining an optimum time-shift variable resulting from the comparison of the first set of measured points against the set of ideal points.

2. A method as in claim 1 wherein the set of ideal points further comprises a variable time shifted set of ideal points.

3. A method as in claim 2 wherein determining the optimum time shift variable further comprises:

determining the optimum time shift variable that yields a minimum squared error between the first set of measured points and the set of ideal points.

4. A method as in claim 1 wherein the correlation function is [(−

|n+a|+8)/8].

5. A method as in claim 1 wherein measuring the plurality of correlation samples further comprises:

measuring a plurality of discrete-time function correlation samples.

6. A method as in claim 1 wherein measuring the plurality of correlation samples further comprises:

measuring a plurality of continuous-time function correlation samples.

7. A method as in claim 1 wherein measuring the plurality of correlation samples further comprises:

measuring a plurality of correlation samples containing discontinuities.

8. A method as in claim 1 wherein measuring the plurality of correlation samples further comprises:

measuring a plurality of correlation samples without discontinuities.

9. A method as in claim 1 wherein measuring the plurality of correlation samples further comprises:

measuring a plurality of correlation samples containing a derivative at every point.

10. A method as in claim 1 wherein measuring the plurality of correlation samples further comprises:

measuring a plurality of correlation samples without a derivative at every point.

11. A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps for timing correction for fast PN acquisition, the method comprising the steps of:

measuring a first set of measured points, wherein the first set of measured points correspond to a first set of measured correlation samples;

determining a set of ideal points;

comparing the first set of measured points against the set of ideal points wherein comparing the first set of measured points against the set of ideal points further comprises;

measuring a plurality of correlation samples;

assigning a first discrete time to the plurality of measured correlation samples;

assigning a time shift in units of measured correlation samples;

determining a theoretical set of discrete magnitudes;

determining a correlation function;

determining where the correlation function equals zero;

zeroing the theoretical set of discrete magnitudes where the correlation function equals zero;

determining a difference between the theoretical set of magnitudes and the measured plurality of correlation samples;

squaring the difference;

summing the squared difference; and

selecting an optimum time-shift variable resulting from the comparison of the first set of measured points against the set of ideal points.

12. A program storage device as in claim 11 wherein the program of instructions comprises at least one Very High Speed Integrated Circuit (VHSIC) Hardware Description (VHDL) Language file.