System and method for frequency management in a communication device having a positioning device

• US 6,741,842 B2
• Filed: 09/30/2002
• Issued: 05/25/2004
• Est. Priority Date: 09/30/2002
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Goldberg, Mark A., Patel, Anil, Korneluk, Jose, Meraj, Atif, Haverkamp, Kristi Annette
• Primary Examiner(s): Urban, Edward F.
• Assistant Examiner(s): Nguyen, Thuan T.
• Application Number:
  US10/259,651
• Publication Number:
  US 20040063411A1
• Time in Patent Office: 603 Days
• Field of Search: 455/192.2, 455/414.1, 455/427, 455/414.2, 455/12.1, 455/456.1, 455/456.3, 455/456.5, 455/456.6, 455/457, 455/75, 455/76, 455/84, 455/255, 455/258, 455/318, 455/556.1
• US Class Current: 455/192.2
• CPC Class Codes: G01S 19/235 Calibration of receiver components
• CPC Class Codes: H04B 1/3805 with built-in auxiliary receivers

Abstract

A frequency management scheme for a hybrid cellular/GPS or other device generates a local clock signal for the communications portion of the device, using a crystal oscillator or other part. The oscillator output may be corrected by way of an automatic frequency control (AFC) circuit or software, to drive the frequency of that clock signal to a higher accuracy. Besides being delivered to the cellular or other communications portion of the hybrid device, the compensated clock signal may also be delivered to a comparator to measure the offset between the cellular oscillator and the GPS oscillator. The error in the cellular oscillator may be measured from the AFC operation in the cellular portion of the device. An undershoot or overshoot in the delta between the two oscillators may thus be deduced to be due to bias in the GPS oscillator, whose value may then be determined. That value may then be used to adjust Doppler search, bandwidth or other GPS receiver characteristics to achieve better time to first fix or other performance characteristics.

Claims

1. A system for generating corrective information based on a frequency reference in a hybrid communications device, comprising:

a first clock source in a communications portion of the communications device, the first clock source generating a first clock signal at a first frequency;

a first clock correction module, communicating with the first clock source, the first clock correction module sensing a first error in the first frequency;

a second clock source in a positioning portion of the communications device, the second clock source generating a second clock signal at a second frequency;

a comparator module, communicating with the first clock source and the second clock source, the comparator module comparing the first frequency and the second frequency to determine a differential error between the first frequency and the second frequency; and

a processor, communicating with the comparator module, the processor adapting a position processing operation based upon at least the first error and the differential error.

2. A system according to claim 1, wherein the communications portion comprises at least one of a cellular telephone, a two-way pager and a network-enabled wireless communication device.

3. A system according to claim 1, wherein the positioning portion comprises a satellite positioning receiver.

4. A system according to claim 3, wherein the satellite positioning receiver comprises a global positioning system receiver.

5. A system according to claim 1, wherein the first clock source comprises a first oscillator.

6. A system according to claim 5, wherein the first clock source comprises a first synthesizer.

7. A system according to claim 6, wherein the first clock source comprises a first phase locked loop.

8. A system according to claim 1, wherein the second clock source comprises a second oscillator.

9. A system according to claim 8, wherein the second clock source comprises a second synthesizer.

10. A system according to claim 9, wherein the second clock source comprises a second phase locked loop.

11. A system according to claim 1, wherein the first clock correction module comprises an automatic frequency control module.

12. A system according to claim 11, wherein the automatic frequency control module comprises an automatic frequency control circuit.

13. A system according to claim 11, wherein the automatic frequency control module comprises an automatic frequency control algorithm.

14. A system according to claim 11, wherein the automatic frequency control module comprises at least a coarse automatic frequency control module.

15. A system according to claim 14, wherein the automatic frequency control module comprises a fine automatic frequency control module.

16. A system according to claim 1, wherein the comparator module comprises a gated counter.

17. A system according to claim 1, wherein the positioning receiver portion comprises a global positioning system receiver.

18. A system according to claim 1, wherein the adapted position processing comprises an adjustment to a Doppler search window used to acquire a positioning signal.

19. A system according to claim 1, wherein the adapted position processing comprises an adjustment to correlator bandwidth used to acquire a positioning signal.

20. A system according to claim 1, wherein the processor determines a second clock error based upon at least the first error and the differential error.

21. A method for generating corrective information based on a frequency reference in a hybrid communications device, comprising:

generating a first clock signal at a first frequency in a communications portion of the communications device;

sensing a first error in the first frequency;

generating a second clock signal at a second frequency in a positioning portion of the communications device;

comparing the first frequency and the second frequency to determine a differential error between the first frequency and the second frequency; and

adapting a position processing operation based upon at least the first error and the differential error.

22. A method according to claim 21, wherein the communications portion comprises at least one of a cellular telephone, a two-way pager and a network-enabled wireless communication device.

23. A method according to claim 21, wherein the positioning portion comprises a satellite positioning receiver.

24. A method according to claim 23, wherein the satellite positioning receiver comprises a global positioning system receiver.

25. A method according to claim 21, wherein the generating a first clock signal comprises operating a first oscillator.

26. A method according to claim 25, wherein the generating a first clock signal comprises operating a first synthesizer.

27. A method according to claim 26, wherein the generating a first clock signal comprises operating a first phase locked loop.

28. A method according to claim 21, wherein the generating a second clock signal comprises operating a second oscillator.

29. A method according to claim 28, wherein the generating a second clock signal comprises operating a second synthesizer.

30. A method according to claim 29, wherein the generating a second clock signal comprises operating a second phase locked loop.

31. A method according to claim 21, wherein the sensing a first error comprises performing an automatic frequency control operation.

32. A method according to claim 31, wherein the performing an automatic frequency control operation comprises operating an automatic frequency control circuit.

33. A method according to claim 31, wherein the performing an automatic frequency control operation comprises executing an automatic frequency control algorithm.

34. A method according to claim 31, wherein the performing an automatic frequency control operation comprises operating at least a coarse automatic frequency control module.

35. A method according to claim 34, wherein the performing an automatic frequency control operation comprises operating a fine automatic frequency control module.

36. A method according to claim 21, wherein the comparing comprises operating a gated counter.

37. A method according to claim 21, wherein the positioning receiver portion comprises a global positioning system receiver.

38. A method according to claim 21, wherein the adapting comprises adjusting a Doppler search window used to acquire a positioning signal.

39. A method according to claim 21, wherein the adapting comprises adjusting a correlator bandwidth used to acquire a positioning signal.

40. A method according to claim 21, further comprising determining a second clock error based upon at least the first error and the differential error.

41. A system for generating corrective information based on a frequency reference in a hybrid communications device, comprising:

first clock means in a communications portion of the communications device, the first clock means generating a first clock signal at a first frequency;

first clock correction means, communicating with the first clock source, the first clock correction means sensing a first error in the first frequency;

second clock means in a positioning portion of the communications device, the second clock means generating a second clock signal at a second frequency;

comparator means, communicating with the first clock means and the second clock means, the comparator means comparing the first frequency and the second frequency to determine a differential error between the first frequency and the second frequency; and

processing means, communicating with the comparator means, the processor means adapting a position processing operation based upon at least the first error and the differential error.

42. A system according to claim 41, wherein the communications portion comprises at least one of a cellular telephone, a two-way pager and a network-enabled wireless communication device.

43. A system according to claim 41, wherein the positioning portion comprises a satellite positioning receiver.

44. A system according to claim 43, wherein the satellite positioning receiver comprises a global positioning system receiver.

45. A system according to claim 41, wherein the first clock means comprises first oscillator means.

46. A system according to claim 45, wherein the first clock means comprises first synthesizer means.

47. A system according to claim 46, wherein the first clock means comprises first phase locked loop means.

48. A system according to claim 41, wherein the second clock means comprises second oscillator means.

49. A system according to claim 48, wherein the second clock means comprises second synthesizer means.

50. A system according to claim 49, wherein the second clock means comprises second phase locked loop means.

51. A system according to claim 41, wherein the first clock correction means comprises automatic frequency control means.

52. A system according to claim 51, wherein the automatic frequency control means comprises an automatic frequency control circuit.

53. A system according to claim 51, wherein the automatic frequency control means comprises an automatic frequency control algorithm.

54. A system according to claim 51, wherein the automatic frequency control means comprises at least a coarse automatic frequency control means.

55. A system according to claim 54, wherein the automatic frequency control means comprises a fine automatic frequency control means.

56. A system according to claim 41, wherein the comparator means comprises gated counter means.

57. A system according to claim 41, wherein the positioning receiver portion comprises global positioning system receiver means.

58. A system according to claim 41, wherein the adapted position processing comprises an adjustment to a Doppler search window used to acquire a positioning signal.

59. A system according to claim 41, wherein the adapted position processing comprises an adjustment to correlator bandwidth used to acquire a positioning signal.

60. A system according to claim 41, wherein the processor means determines a second clock error based upon at least the first error and the differential error.