Radiation-hardened fast acquistion/weak signal tracking system and method

• US 20060082496A1
• Filed: 09/20/2005
• Published: 04/20/2006
• Est. Priority Date: 09/20/2004
• Status: Active Grant

• Current Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Original Assignee: U.S.A. as represented by the Administrator of the National Aeronautics and Space Administration
• Inventors: Sirotzky, Steve, Winternitz, Luke, Boegner, Gregory J.
• Granted Patent: US 7,548,199 B2
• Time in Patent Office: Days
• US Class Current: 342/357.630
• CPC Class Codes: G01S 19/14 specially adapted for specific applications
• CPC Class Codes: G01S 19/29 carrier including Doppler, related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/37 Hardware or software details of the signal processing chain

Abstract

A global positioning system (GPS) receiver and method of acquiring and tracking GPS signals comprises an antenna adapted to receive GPS signals; an analog radio frequency device operatively connected to the antenna and adapted to convert the GPS signals from an analog format to a digital format; a plurality of GPS signal tracking correlators operatively connected to the analog RF device; a GPS signal acquisition component operatively connected to the analog RF device and the plurality of GPS signal tracking correlators, wherein the GPS signal acquisition component is adapted to calculate a maximum vector on a databit correlation grid; and a microprocessor operatively connected to the plurality of GPS signal tracking correlators and the GPS signal acquisition component, wherein the microprocessor is adapted to compare the maximum vector with a predetermined correlation threshold to allow the GPS signal to be fully acquired and tracked.

Claims

1. A global positioning system (GPS) receiver comprising:

a GPS signal acquisition component comprising a frequency domain correlation module,

wherein said GPS signal acquisition component is adapted to acquire said GPS signals with a Effective Isotropic Received Power (EIRP) of at least about −

180 dBW, and

wherein said GPS receiver is adapted to operate in a space environment.

2. The GPS receiver of claim 1, further comprising:

a plurality of GPS signal tracking correlators adapted to track said GPS signals with an EIRP of at least about −

175 dBW.

3. The GPS receiver of claim 2, wherein said GPS signal tracking correlators comprise a field-programmable gate array (FPGA).

4. The GPS receiver of claim 1, wherein said GPS signal acquisition component comprises a field-programmable gate array (FPGA).

5. The GPS receiver of claim 1, wherein said GPS signal acquisition component is adapted to acquire a GPS signal within about one minute for GPS signals with an EIRP greater than about −

180 dBW.

6. The GPS receiver of claim 1, wherein said GPS signal acquisition component is adapted to acquire a GPS signal within about one second for GPS signals with an EIRP greater than about −

160 dBW.

7. The GPS receiver of claim 1, wherein said GPS signal acquisition component is adapted to acquire a GPS signal within about one minute for GPS signals with an EIRP greater than about −

180 dBW,.and to acquire a GPS signal within about one second for GPS signals with an EIRP greater than about −

160 dBW.

8. The GPS receiver of claim 1, wherein said GPS signal acquisition component is adapted to perform a Fast Fourier Transform (FFT) correlation process on said GPS signals.

9. The GPS receiver of claim 1, wherein said GPS signal acquisition component is adapted to acquire a GPS signal without a priori data.

10. A global positioning system (GPS) receiver comprising:

a GPS signal acquisition component comprising a frequency domain correlation module,

wherein said GPS signal acquisition component is adapted to acquire a GPS signal within about one second for GPS signals with an EIRP greater than about −

160 dBW, and

wherein said GPS receiver is adapted to operate in a space environment.

11. The GPS receiver of claim 10, further comprising:

a plurality of GPS signal tracking correlators adapted to track said GPS signals with an EIRP of at least about −

175 dBW.

12. The GPS receiver of claim 10, wherein said GPS signal tracking correlators comprise a field-programmable gate array (FPGA).

13. The GPS receiver of claim 10, wherein said GPS signal acquisition component comprises a field-programmable gate array (FPGA).

14. The GPS receiver of claim 10, wherein said GPS signal acquisition component comprises a frequency domain correlation module.

15. The GPS receiver of claim 10, wherein said GPS signal acquisition component is adapted to acquire a GPS signal with an EIRP greater than about −

180 dBW.

16. The GPS receiver of claim 10, wherein said GPS signal acquisition component is adapted to acquire a GPS signal within about one minute for GPS signals with an EIRP greater than about −

180 dBW.

17. The GPS receiver of claim 10, wherein said GPS signal acquisition component is adapted to perform a Fast Fourier Transform (FFT) correlation process on said GPS signals.

18. The GPS receiver of claim 10, wherein said GPS signal acquisition component is adapted to acquire a GPS signal without a priori data for GPS signals with an EIRP greater than about 180 dBW.

19. A global positioning system (GPS) receiver comprising:

a GPS signal acquisition component comprising a frequency domain correlation module,

wherein said GPS signal acquisition component is adapted to acquire said GPS signals with an EIRP of at least about −

180 dBW without a priori data, and

wherein the acquired GPS signal is acquired substantially in real time.

20. The GPS receiver of claim 19, further comprising:

a plurality of GPS signal tracking correlators adapted to track said GPS signals with an EIRP of at least about −

175 dBW.

21. The GPS receiver of claim 20, wherein said GPS signal tracking correlators comprising a field-programmable gate array (FPGA).

22. The GPS receiver of claim 19, wherein said GPS signal acquisition component comprises a field-programmable gate array (FPGA).

23. The GPS receiver of claim 19, wherein said GPS signal acquisition component is adapted to acquire a GPS signal within about one minute for GPS signals with an EIRP greater than about about −

180 dBW.

24. The GPS receiver of claim 19, wherein said GPS signal acquisition component is adapted to acquire a GPS signal within about one second for GPS signals with an EIRP greater than about −

160 dBW.

25. The GPS receiver of claim 19, wherein said GPS signal acquisition component is adapted to acquire a GPS signal within about one minute for GPS signals with an EIRP greater than about about −

180 dBW,.and to acquire a GPS signal within about one second for GPS signals with an EIRP greater than about −

160 dBW.

26. The GPS receiver of claim 19, wherein said GPS signal acquisition component is adapted to perform a Fast Fourier Transform (FFT) correlation process on said GPS signals.

27. The GPS receiver of claim 19, wherein said GPS signal acquisition component is adapted to acquire a GPS signal without a priori data.

28. A method of acquiring and tracking global positioning system (GPS) signals, said method comprising:

receiving GPS signals;

performing a frequency domain correlation process on said GPS signals;

comparing the correlated GPS signals with a predetermined threshold; and

acquiring a GPS signal if a correlated GPS signal exceeds the predetermined threshold.

29. The method of claim 28, wherein the step of performing a frequency domain correlation process comprises performing a Fast Fourier Transform (FFT) correlation process for a plurality of frequency increments of the received GPS signals;

and wherein the step of acquiring a GPS signal comprises acquiring the GPS signal if a correlated GPS signal exceeds the predetermined threshold for any of the frequency increments.

30. The method of claim 28, further comprising receiving GPS signals for a plurality of time increments, and accumulating the correlated GPS signals over a plurality of time increments to permit the acquisition of GPS signals with substantially lower received EIRP.

31. The method of claim 30, wherein each of the plurality of time increments is about 1 ms.

32. The method of claim 28, further comprising:

acquiring said GPS signals at an EIRP of at least about −

180 dBW.

33. The method of claim 28, further comprising:

tracking said GPS signals at an EIRP of at least about −

175 dBW.

34. The method of claim 28, further comprising:

acquiring a GPS signal within about one minute for GPS signals with an EIRP greater than about −

180 dBW.

35. The method of claim 28, further comprising acquiring a GPS signal within about one second for GPS signals with an EIRP greater than about −

160 dBW

36. The method of claim 28, further comprising acquiring a GPS signal with an EIRP greater than about −

180 dBW within about one minute, and acquiring a GPS signal with an EIRP greater than about −

160 dBW within about one second.

37. The method of claim 28, further comprising acquiring a GPS signal with an EIRP greater than about −

180 dBW without a priori data

38. A method of acquiring and tracking global positioning system (GPS) signals, said method comprising:

receiving GPS signals for a plurality of time increments;

performing a frequency domain correlation process on said GPS signals for each of the plurality of time increments;

comparing the correlated GPS signals with a predetermined threshold; and

acquiring a GPS signal if a correlated GPS signal exceeds the predetermined threshold for any of the plurality of time increments.

39. The method of claim 38, wherein each of the plurality of time increments is about 1 ms.

40. The method of claim 38, wherein the step of performing a frequency domain correlation process comprises performing a Fast Fourier Transform (FFT) correlation process for a plurality of frequency increments of the received GPS signals for each of the plurality of time increments;

and wherein the step of acquiring the GPS signal comprises acquiring a GPS signal if a correlated GPS signal exceeds the predetermined threshold for any of the frequency increments for any of the time increments.

41. The method of claim 38, further comprising:

acquiring a GPS signals with an EIRP of at least about −

180 dBW.

42. The method of claim 38, further comprising:

tracking a GPS signals with an EIRP of at least about −

175 dBW.

43. The method of claim 38, further comprising acquiring a GPS signal with an EIRP greater than about −

180 dBW within about one minute.

44. The method of claim 38, further comprising acquiring a GPS signal with an EIRP greater than about −

160 dBW within about one second.

45. The method of claim 38, further comprising acquiring a GPS signal within about one minute for GPS signals with an EIRP greater than about about −

180 dBW, and acquiring a GPS signal within about one second for GPS signals with an EIRP greater than about −

160 dBW.

46. The method of claim 38, further comprising acquiring a GPS signal with an EIRP greater than about −

180 dBW without a priori data.

47. A computer program embodied in a computer readable medium for acquiring and tracking global positioning system (GPS) signals, said program comprising:

a receiver module for receiving GPS signals;

a correlation module for performing a frequency domain correlation process on said GPS signals;

a comparison module for comparing the correlated GPS signals with a predetermined threshold; and

an acquisition module for acquiring a GPS signal if a correlated GPS signal exceeds the predetermined threshold to allow said GPS signal to be acquired and tracked.

48. The computer program of claim 47, wherein the correlation module is adapted to perform the frequency domain correlation process by controlling a hardware acquisition component.

49. The computer program of claim 47, wherein the hardware acquisition component comprises a field-programmable gate array (FPGA).

50. The computer program of claim 47, wherein the computer readable medium is radiation hardened.

51. The computer program of claim 47, wherein:

the receiver module is adapted to receive GPS signals for one or more time increments;

the frequency domain correlation process comprises a Fast Fourier Transform (FFT) correlation process for a plurality of frequency increments of the received GPS signals for each of the one or more time increments; and

the acquisition module is adapted to acquire a GPS signal if the correlated GPS signal exceeds the predetermined threshold for any of the frequency increments for any of the one or more time increments.

52. The computer program of claim 47, wherein:

the acquisition module is adapted to acquire GPS signals with an EIRP of at least about −

180 dBW.

53. The computer program of claim 47, further comprising:

a tracking module for tracking GPS signals with an EIRP of at least about −

175 dBW.

54. The computer program of claim 47, wherein said acquisition module is capable of acquiring a GPS signal with an EIRP greater than about −

180 dBW within about one minute.

55. The computer program of claim 47, wherein said acquisition module is capable of acquiring a GPS signal with an EIRP greater than about −

160 dBW within about one second.

56. The computer program of claim 47, wherein the receiver module receives GPS signals via a hardware receiver.