Claims
- 1. A method of acquiring a burst code signal comprising:
generating a plurality of pulse trains, each having a different timing; and simultaneously comparing the burst code signal to each of the plurality of pulse trains, wherein the burst code signal and the plurality of generated pulse trains are synchronized to a timing signal; and detecting which of the pulse trains is a closest temporal match to the burst code signal.
- 2. The method of claim 1, wherein the plurality of pulse trains are generated by a pseudo noise code generator and synchronizing the plurality of generated pulse trains comprises bringing a chipping rate of the pseudo noise code generator into approximate agreement with the accuracy of the timing signal.
- 3. The method of claim 2, wherein synchronizing the plurality of generated pulse trains further comprises maintaining a composite pseudo noise code phase of pseudo noise code generator substantially coincident with a phase of the timing signal.
- 4. The method of claim 1, wherein the timing signal is a GPS timing signal.
- 5. The method of claim 4, wherein synchronizing the plurality of generated pulse trains comprises adjusting a pseudo noise code phase of a pseudo noise code generator to have the same phase as it would have had it begun at the beginning of a GPS day and progressed at a nominal chipping rate ideally achieved with a reference oscillator used for generating the GPS timing signal.
- 6. The method of claim 4, wherein synchronizing the plurality of generated pulse trains comprises bringing the chipping rate of a pseudo noise code generator approximately to the accuracy of the GPS timing signal.
- 7. The method of claim 6, wherein synchronizing the plurality of generated pulse trains further comprises maintaining a composite PN code phase of the PN code generator substantially at a GPS time of day.
- 8. The method of claim 1, wherein simultaneously comparing the burst code signal to each of the plurality of pulse trains includes generating a correlation value for each comparison.
- 9. The method of claim 8, wherein detecting which of the pulse trains is a closest temporal match is performed by comparing the correlation values.
- 10. The method of claim 8, wherein simultaneously comparing the burst code signal to each of the plurality of pulse trains utilizes a finite impulse response filter having an impulse response time.
- 11. The method of claim 10, wherein the burst code signal and the plurality of pulse trains are synchronized to be within the impulse response time.
- 12. A digital communication system comprising:
a generator for generating a plurality of pulse trains, each having a different timing; pre-compensation circuitry for synchronizing the plurality of pulse trains to a timing signal comparison circuitry for simultaneously comparing a received burst code signal to each of the plurality of pulse trains, wherein the received burst code signal is synchronized to the timing signal; and detection circuitry for detecting which of the pulse trains is a closest temporal match to the received burst code signal.
- 13. The system of claim 12, wherein the generator comprises a pseudo noise code generator.
- 14. The system of claim 13, wherein the pre-compensation circuitry comprises an output signal for bringing a chipping rate of the pseudo noise code generator into approximate agreement with the accuracy of the timing signal.
- 15. The system of claim 14, wherein the pre-compensation circuitry further comprises an output signal for maintaining a composite pseudo noise code phase of the pseudo noise code generator substantially coincident with a phase of the timing signal.
- 16. The system of claim 12, wherein the wherein the timing signal is a GPS timing signal.
- 17. The system of claim 16, wherein the generator comprises a pseudo noise generator.
- 18. The system of claim 17, wherein the pre-compensation circuitry comprises an output signal for adjusting a pseudo noise code phase of the pseudo noise code generator to have the same phase as it would have had it begun at the beginning of a GPS day and progressed at a nominal chipping rate ideally achieved with a reference oscillator used for generating the GPS timing signal.
- 19. The system of claim 17, wherein the pre-compensation circuitry comprises an output signal for bringing a chipping rate of the pseudo noise code generator into approximate agreement with the accuracy of the GPS timing signal.
- 20. The system of claim 17, wherein the pre-compensation circuitry further comprises an output signal for maintaining a composite pseudo noise code phase of the pseudo noise code generator substantially at a GPS time of day.
- 21. The system of claim 12, wherein the comparison circuitry generates a correlation value for each comparison.
- 22. The system of claim 21, wherein the detection circuitry detects which of the pulse trains is a closest temporal match to the received burst code signal, by comparing the correlation values.
- 23. The system of claim 21, wherein the comparison circuitry comprises a finite impulse response filter having an impulse response time.
- 24. The system of claim 23, wherein the pre-compensation circuitry synchronizes the plurality of pulse trains to be within the impulse response time.
- 25. A method of acquiring a burst code signal comprising:
generating a plurality of pulse trains using a pseudo noise code generator, wherein each of the pulse trains has a different timing; synchronizing a chipping rate of the pseudo noise code generator with a timing signal; maintaining a composite pseudo noise code phase of the pseudo noise code generator substantially coincident with a phase of the timing signal; simultaneously comparing the burst code signal to each of the plurality of pulse trains, wherein the burst code signal and the plurality of generated pulse trains are synchronized to a timing signal; and detecting which of the pulse trains is a closest temporal match to the burst code signal.
- 26. The method of claim 25, wherein the timing signal is a GPS timing signal.
- 27. The method of claim 26, wherein synchronizing the plurality of generated pulse trains comprises adjusting a pseudo noise code phase of a pseudo noise code generator to have the same phase as it would have had it begun at the beginning of a GPS day and progressed at a nominal chipping rate ideally achieved with a reference oscillator used for generating the GPS timing signal.
- 28. The method of claim 26, wherein synchronizing the plurality of generated pulse trains comprises bringing the chipping rate of a pseudo noise code generator approximately to the accuracy of the GPS timing signal.
- 29. The method of claim 28, wherein synchronizing the plurality of generated pulse trains further comprises maintaining a composite PN code phase of the PN code generator substantially at a GPS time of day.
- 30. A digital communication system comprising a pluralty of platforms, each platform including:
a pseudo noise code generator for generating a plurality of pulse trains, each having a different timing; pre-compensation circuitry for correcting a clock rate of the pseudo noise generator to approximate a clock rate of a timing signal, and for maintaining a composite pseudo noise code phase of the pseudo noise code generator substantially coincident with a phase of the timing signal; correlation circuitry for simultaneously correlating a received burst code signal with each of the plurality of pulse trains, wherein the received burst code signal is synchronized to the timing signal; and detection circuitry for detecting which of the pulse trains is a closest temporal match to the received burst code signal.
- 31. The system of claim 30, wherein the wherein the timing signal is a GPS timing signal.
- 32. The system of claim 31, wherein the pre-compensation circuitry comprises an output signal for adjusting a pseudo noise code phase of the pseudo noise code generator to have the same phase as it would have had it begun at the beginning of a GPS day and progressed at a nominal chipping rate ideally achieved with a reference oscillator used for generating the GPS timing signal.
- 33. The system of claim 31, wherein the pre-compensation circuitry comprises an output signal for bringing a chipping rate of the pseudo noise code generator into approximate agreement with the accuracy of the GPS timing signal.
- 34. The system of claim 31, wherein the pre-compensation circuitry further comprises an output signal for maintaining a composite pseudo noise code phase of the pseudo noise code generator substantially at a GPS time of day.
- 35. The system of claim 30, wherein the correlation circuitry comprises a finite impulse response filter having an impulse response time.
- 36. The system of claim 35, wherein the pre-compensation circuitry synchronizes the plurality of pulse trains to be within the impulse response time.
CROSS REFERENCES TO RELATED APPLICATIONS
[0001] The present application is related to U.S. Pat. Nos. 6,201,843, 5,134,631, 5,128,958, 5,105,437, 5,062,071, 5,099,494, 5,060,180, 5,084,913, 5,101,370, 4,841,552, 4,808,939, and 5,022,048.