Distributed GPS navigation system

• US 6,430,503 B1
• Filed: 01/06/1998
• Issued: 08/06/2002
• Est. Priority Date: 01/06/1998
• Status: Expired due to Term

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Woo, Arthur N., McBurney, Paul W.
• Primary Examiner(s): Issing, Gregory C.
• Application Number:
  US09/003,316
• Time in Patent Office: 1,673 Days
• Field of Search: 701/207, 701/213, 342/357.12, 342/357.09, 342/357.15
• US Class Current: 701/213
• CPC Class Codes: G01C 21/20 Instruments for performing navigational calculations G01C21/24, G01C21/26 take precedence
• CPC Class Codes: G01S 19/254 relating to Doppler shift of satellite signals
• CPC Class Codes: G01S 19/256 relating to timing, e.g. time of week, code phase, timing offset
• CPC Class Codes: G01S 19/34 Power consumption
• CPC Class Codes: G01S 19/36 relating to the receiver frond end

Abstract

A system and method which separates time critical interrupt driven processing of Global Positioning System (GPS) signals from non-time critical processing. A measurement platform performs all satellite tracking functions which are driven by interrupts. Intermediate measurements data generated therefrom, for example code phase, carrier phase and Doppler, are communicated to a user platform which computes receiver position and time. As a result, the user platform can easily be configured to perform user-specific processes without incurring conflicts with the interrupt driven processes occurring on the measurement platform.

Claims

1. A system for processing navigation information from positioning signals comprising:

a measurement platform powered by a first power source comprising

a positioning signal receiver comprising an antenna and downconverter configured to receive positioning signals and generate positioning data for multiple channels;

a channel unit coupled to the positioning signal receiver and configured to receive in real time the positioning data for multiple channels, perform time critical intermediate positioning calculations at a time critical rate, generate intermediate positioning data and transmit the intermediate positioning data; and

a user platform external to the measurement platform and powered by a second power source comprising

a general purpose processing system bi-directionally communicatively coupled to the channel unit, the processing system receiving the intermediate positioning data from the channel unit of the measurement platform and calculating the position information from the intermediate positioning data, wherein the general purpose processing system is user programmable to execute applications utilizing the intermediate positioning data in a multitask environment concurrently together with other user applications.

2. The system as set forth in claim 1, wherein the channel unit further comprises a buffer for buffering the intermediate positioning data.

3. The system as set forth in claim 1, wherein the channel unit performs time critical intermediate positioning calculations in response to interrupts indicating that the positioning calculations are to be performed.

4. The system as set forth in claim 1, wherein the channel unit performs time critical intermediate positioning calculations on a real time basis.

5. The system as set forth in claim 1, wherein the general purpose processing system on the user platform further performs application processing using the intermediate positioning data provided.

6. The system as set forth in claim 1, further comprising a serial line coupled between the channel unit of the measurement platform and the general purpose processing system of the user platform to transmit intermediate positioning data and carry out other bi-directional communication.

7. The system as set forth in claim 1, further comprising a wireless connection between the channel unit of the measurement platform and the general purpose processing system of the user platform to transmit intermediate positioning data and carry out other bi-directional communication.

8. The system as set forth in claim 1, further comprising a connection formed by a plurality of parallel lines between the channel unit of the measurement platform and the general purpose processing system of the user platform for transmitting intermediate positioning data and carry out other bi-directional communication.

9. The system as set forth in claim 1, wherein the intermediate positioning data comprises code phase data.

10. The system as set forth in claim 1, wherein the intermediate positioning data comprises carrier phase data.

11. The system as set forth in claim 1, wherein the intermediate positioning data comprises Doppler data.

12. The system as set forth in claim 1, wherein the channel unit comprises a memory, said memory configured to store instructions executed by the channel unit.

13. The system as set forth in claim 12, wherein the channel unit of the measurement platform comprises a read only memory to store the instructions and a random access memory to temporarily buffer intermediate positioning data prior to output to the general purpose processing system of the user platform.

14. The system of claim 1, wherein the user platform transmits preposition data to the measurement platform, and wherein the preposition data contains information regarding a location at which the measurement platform may begin a search for a satellite.

15. The system of claim 1, wherein the user platform includes a real time clock, and wherein the real time clock is operable to provide an estimate of a current time for use in making a selection regarding which satellites may be visible to the measurement platform.

16. A measurement platform powered by a first power source comprising a channel unit configured to receive in real time from downconverter circuitry positioning data for multiple channels, the channel unit configured to perform time critical intermediate positioning calculations at a time critical rate and generate intermediate positioning data, the channel unit further configured to output the intermediate positioning data to a bi-directionally communicatively coupled processing device located on an external user platform powered by a second power source for subsequent calculations of position or time information from the received intermediate positioning data.

17. The measurement platform of claim 16, wherein the channel unit comprises a memory, said memory configured to store instructions executed by the channel unit.

18. The measurement platform of claim 17, wherein the channel unit comprises a read only memory to store the instructions and a random access memory to temporarily buffer intermediate positioning data prior to output to the external processing device.

19. The measurement platform of claim 16, wherein the channel unit further comprises a buffer configured to buffer the intermediate positioning data prior to output.

20. The measurement platform of claim 16, wherein, the channel unit further comprises a wireless port configured to output intermediate positioning data.

21. The measurement platform of claim 16, wherein the channel unit is configured to perform time critical intermediate positioning calculations on a real time basis.

22. The measurement platform of claim 16, wherein the channel unit further comprises a serial port configured to output the intermediate positioning data.

23. The measurement platform of claim 16, wherein, the channel unit further comprises a parallel port configured to output the intermediate positioning data.

24. A method comprising:

receiving positioning signals transmitted;

performing time critical calculations to track positioning signal transmitters at a time critical rate and generating intermediate positioning data used to determine a position of a receiver on a measurement platform powered by a first power source;

transmitting the intermediate positioning data to an external user platform powered by a second power source; and

the user platform computing the position of the receiver in a multitask environment together with other applications executing on the user platform.

25. The method as set forth in claim 24, further comprising buffering the intermediate positioning data prior to the transmitting.

26. The method as set forth in claim 24, further comprising the user platform performing applications processing using the computed position of the receiver.

27. The method as set forth in claim 24, wherein the performing time critical calculations generates code phase data.

28. The method as set forth in claim 24, wherein the performing time critical calculations generates carrier phase data.

29. The method as set forth in claim 24, wherein the performing time critical calculations generates Doppler data.

30. A computer readable medium comprising instructions which, when executed by a processor located on a user platform powered by a first power source, generate navigation solutions comprising:

receiving intermediate positioning data from a coupled channel unit located on an external measurement platform powered by a second power source, the coupled channel unit being configured to receive in real time positioning data for multiple channels, perform time critical intermediate positioning calculations including acquisition and tracking at a time critical rate, generate intermediate positioning data, and transmit the intermediate positioning data to the processor on the user platform executing the instructions stored on the computer readable medium in a multitask environment together with other user applications; and

calculating navigation solutions using the intermediate positioning data.

31. The computer readable medium as set forth in claim 30, wherein the navigation solution is selected from a group comprising position and time.

32. The method as set forth in claim 30, wherein the navigation solution is selected from a group comprising position and time.

33. The method as set forth in claim 30, further comprising buffering intermediate positioning data prior to the transmitting.

34. The method as set forth in claim 30, further comprising the user platform performing applications processing using the computed position of a receiver.

35. The method as set forth in claim 30, wherein performing time critical calculations generates data selected from a group comprising code phase data, carrier phase data and Doppler data.

36. A method comprising:

receiving positioning signals from satellite positioning transmitters;

bi-directionally communicatively coupling a measurement platform powered by a first power source to an external user platform powered by a second power source, wherein the measurement platform contains a first processor and the user platform contains a general purpose processor;

performing calculations with the first processor to track the satellite positioning transmitters, wherein the calculations are performed at a time critical rate;

generating intermediate positioning data from the calculations performed by the first processor;

transmitting the intermediate positioning data from the measurement platform to the user platform;

performing navigation calculations with the general purpose processor in a multitask environment together with the execution of other user applications.

37. The method of claim 36, wherein the intermediate data comprises code phase data, carrier phase data, or Doppler data.

38. The method of claim 37, wherein the intermediate data constitutes a snapshot of the code phase data, carrier phase data, or Doppler data.

39. The method of claim 37, wherein the intermediate data constitutes an average of the code phase data, carrier phase data, or Doppler data.

40. The method of claim 36, wherein the intermediate data is encrypted prior to transmission.

41. The method of claim 36, wherein the user platform transmits preposition data to the measurement platform, and wherein the preposition data contains information regarding a location at which the measurement platform may begin a search for a satellite.

42. The method of claim 36, wherein the user platform includes a real time clock, and wherein the real time clock is operable to provide an estimate of a current time for use in making a selection regarding which satellites may be visible to the measurement platform.

43. The method of claim 36, wherein the first processor is a dedicated processor that only performs functions related to positioning.

44. The method of claim 36, wherein the user platform comprises a personal computer.

45. The method of claim 36, wherein the navigation calculations are performed by a plurality of processors.

46. The method of claim 36, wherein the user platform has a different operating system than the measurement platform.

47. A positioning measurement platform comprising:

a first power source to power the positioning measurement platform;

circuitry to process positioning signals received from satellite transmitters; and

a channel unit including a first processor, wherein the channel unit is operable to;

receive the processed positioning signals;

perform intermediate positioning calculations at a time critical rate,

generate intermediate positioning data, and

transmit the intermediate positioning data to a user platform powered by a second power source, wherein the user platform contains a general purpose processor to calculate navigation information using the intermediate positioning data in a multitask environment together with the execution of other user applications.

48. The positioning measurement platform of claim 47, wherein the intermediate positioning data comprises code phase data, carrier phase data, or Doppler data.

49. The positioning measurement platform of claim 48, wherein the intermediate positioning data constitutes a snapshot of the code phase data, carrier phase data, or Doppler data.

50. The positioning measurement platform of claim 48, wherein the intermediate data constitutes an average of the code phase data, carrier phase data, or Doppler data.

51. The positioning measurement platform of claim 47, wherein the intermediate positioning data is encrypted prior to transmission.

52. The positioning measurement platform of claim 47, wherein the user platform transmits preposition data to the positioning measurement platform, and wherein the preposition data contains information regarding a location at which the positioning measurement platform may begin a search for a satellite.

53. The positioning measurement platform of claim 47, wherein the user platform includes a real time clock, and wherein the real time clock is operable to provide an estimate of a current time for use in making a selection regarding which satellites may be visible to the positioning measurement platform.

54. The positioning measurement platform of claim 47, wherein the first processor is a dedicated processor that only performs functions related to positioning.

55. The positioning measurement platform of claim 47, wherein the user platform comprises a personal computer.

56. The positioning measurement platform of claim 47, wherein the navigation calculations are performed by a plurality of processors.

57. The positioning measurement platform of claim 47, wherein the user platform has a different operating system than the measurement platform.

58. A computer readable medium comprising instructions which, when executed by a processor located on a measurement platform powered by a first power source cause a channel unit to:

receive in real time from downconverter circuitry positioning data for multiple channels;

generate intermediate positioning data;

output the intermediate positioning to a bi-directionally communicatively coupled processing device located on an external user platform powered by a second power source for subsequent calculations of at least one of position or time information from the received intermediate positioning data in a multitask environment together with the execution of other user applications.