METHOD AND SYSTEM FOR ALL-IN-VIEW COHERENT GPS SIGNAL PRN CODES ACQUISITION AND NAVIGATION SOLUTION DETERMINATION

• US 20090262014A1
• Filed: 08/09/2006
• Published: 10/22/2009
• Est. Priority Date: 03/15/2006
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: DiEsposti, Raymond S.
• Granted Patent: US 7,619,559 B2
• Time in Patent Office: Days
• US Class Current: 342/357.420
• CPC Class Codes: G01S 19/05 providing aiding data
• CPC Class Codes: G01S 19/25 involving aiding data received from a cooperating element, e.g. assisted GPS
• CPC Class Codes: G01S 19/252 Employing an initial estimate of location in generating assistance data

Abstract

A method and system for enabling more robust detection, positioning and time solution using GPS satellite ranging signals based on a simultaneous, all-in-view coherent PRN code signal processing scheme rather than acquisition of GPS signals one at a time. Additionally, a plurality of signal processing operating modes are provided that include a Factory Start mode, a Hot Start mode, a Subsequent Fix mode and a Reacquisition mode. Each mode provides a user receiver with an ability to quickly determine its current probable location without undue delay when a prior probable location has been obtained. Preventing undue delay of predicting a probable location of the user can be especially valuable in conditions where weak signals are being received, or in high interference environments, or when signal jamming conditions are being experienced, or when a combination of such environments is present.

Claims

1. A method for rapidly acquiring and using a plurality of satellite ranging signals to determine position information, the method comprising:

using a first user receiver to receive information from a remote source and satellite ranging signals from satellites within view of said first user receiver, to determine a probable location of the first user receiver;

transmitting from the first user receiver, the probable location of the first user receiver and the information to a second user receiver;

using the information and the first user receiver probable location to limit an Earth-reference search space region associated with the second user receiver to predetermined geographic dimensions;

using the second user receiver to simultaneously obtain a plurality of satellite ranging signals from each one of a plurality of said satellites within view of said second user receiver; and

causing the second user receiver to use the obtained satellite ranging signals and the probable location of the first user receiver to rapidly obtain a probable geographic location of the second user receiver by coherently combining the power in the received satellite ranging codes received from said plurality of satellites at a plurality of grid points within said search space region.

2. The method of claim 1, further comprising synchronizing operation of said second user receiver with said first user receiver to define an epoch time.

3. The method of claim 1, wherein the information comprises at least one of:

code phase ranging data;

almanac data;

satellite ephemeris data;

clock data;

size or boundary data; and

base station ranging measurements for the search space grid.

5. The method of claim 1, wherein transmitting from the first user receiver the probable location of the first user receiver and the information further comprises:

transmitting from the first user receiver probable location of the first user receiver and the information via a cable.

6. The method of claim 1, wherein transmitting from the first user receiver the probable location of the first user receiver and the information further comprises transmitting from the first user receiver said probable location of the first user receiver and the information via a wireless communication link.

7. The method of claim 1, wherein the second user receiver acquires the satellite ranging signals after receiving the information, after performing a time synchronization operation, and after receiving the probable location of the first user receiver.

8. The method of claim 1, wherein the geographic dimensions comprise one of a two-dimensional region or a three-dimensional region of Earth coordinates.

4. (canceled)

9. A method for rapidly acquiring and using a plurality of satellite ranging signals to determine position information, the method comprising:

using a first user receiver to receive satellite ranging signals from satellites within view of said first user receiver, to determine a probable location of the first user receiver;

transmitting from the first user receiver the probable location of the first user receiver and additional information to a second user receiver to assist said second user receiver in determining its position;

using the additional information and the first user receiver probable location to limit an Earth-reference search space region associated with the second user receiver to predetermined geographic dimensions;

using the second user receiver to search a grid defined by said predetermined geographic dimensions to simultaneously obtain satellite ranging signals from a plurality of said satellites within view of said second user receiver; and

causing the second user receiver to use the obtained satellite ranging signals and the probable location of the first user receiver to rapidly obtain a probable geographic location of the second user receiver by coherently combining the power in the received satellite ranging codes.

10. The method of claim 9, further comprising synchronizing operation of said second user receiver with said first user receiver to define an epoch time.

11. The method of claim 9, wherein the other information comprises at least one of:

code phase ranging data;

almanac data;

satellite ephemeris data;

clock data; and

size or boundary data.

12. The method of claim 9, wherein the operation of transmitting from the first user receiver the probable location of the first user receiver and the other information comprises using at least one of a cable and a wireless link to perform said transmitting operation.

13. A method for enabling a user receiver to rapidly acquire and use a plurality of satellite ranging signals having satellite codes to rapidly determine a position of the user receiver, the method comprising:

receiving a set of initialization data and remote source location data, from a remote source, to limit a first Earth-reference search space region, in which the user receiver is located, to predetermined geographic dimensions;

receiving a time synch function, from the remote source, to synchronize a user receiver clock of the user receiver and calibrate a user receiver oscillator such that the user receiver clock and the user receiver oscillator maintain time;

acquiring simultaneously with said initialization data at least one of the satellite codes from each one of a plurality of satellites in view of the user receiver;

coherently combining said acquired satellite codes from a plurality of said satellites in view of said user receiver to detect therefrom a first probable location of the user receiver at a first epoch time;

determining a time lapse since the first probable location was detected;

predicting a second set of initialization data, using the time lapse and received set of initialization data, to limit a second Earth-reference search space region to a second set of predetermined geographic dimensions;

acquiring simultaneously at least one of the satellite codes from each of the plurality of satellites in view of the user receiver; and

coherently combining said acquired satellite codes to detect therefrom a second probable location of the user receiver within the second Earth-reference search space region at a second epoch time.

14. The method of claim 13, further comprising:

determining a second time lapse since determination of the second probable location;

predicting a third set of initialization data to limit a third Earth-reference search space region to a third set of predetermined geographic dimensions;

acquiring simultaneously at least one of the satellite codes from the plurality of satellites in view of the user receiver; and

coherently combining received satellite codes to detect therefrom a third probable location of the user receiver within the third Earth-reference search space region at a third epoch time.

15. The method of claim 13, wherein predicting the second set of initialization data further comprises:

powering down said user receiver into a standby operating mode in which the user receiver stops processing received satellite codes; and

predicting the second set of initialization data when the user receiver transitions from the standby operating mode and again begins acquiring the satellite codes.

16. The method of claim 13, wherein predicting the second set of initialization data further comprises:

predicting the second set of initialization data after the user receiver stops acquiring said satellite codes for a predetermined period of time, and then restarts acquiring said satellite codes at a future epoch time; and

predicting satellite orbit and clock motion associated with the lapsed time from saved information.

17. The method of claim 13, wherein predicting the second set of initialization data, using the amount of time lapsed, to limit a second search space grid further comprises:

computing a user receiver velocity at the epoch time to estimate and bound dimensions of user motion, and;

further limiting the second search space grid based on the user receiver velocity.

18. The method of claim 13, wherein the user receiver further uses other information saved within the user receiver comprising at least one of the following to assist in determining said second probable location:

code phase ranging data;

almanac data;

satellite ephemeris data;

clock data; and

size or boundary data.

19. The method of claim 13, wherein each said set of initialization data and the time synch function or user receiver clock are used to predict at least one satellite code phase for each of the plurality of satellites at a search grid point of the first Earth-reference search space region.

20. The method of claim 13, wherein the operation of combining coherently the received satellite codes comprises:

analyzing a power output produced by each of the acquired satellite codes at each of a plurality of grid point locations in the second search space region;

summing all of the power outputs in the user receiver for each of the plurality of grid point locations; and

determining when a summed power output indicates a maximum coherently combined power value for the plurality of grid point locations within the geographic dimensions to identify the probable location of the user receiver.

21. The method of claim 13, wherein the geographic dimensions comprises a two-dimensional grid or a three-dimensional grid of Earth-reference coordinates.

22. The method of claim 13, wherein the first set of initialization data comprises at least one of:

almanac data

satellite ephemeris data;

clock data; and

size or boundary data relating to the first set of initialization data, and base station ranging measurements for the first Earth-reference search space region.

23. A method for rapidly acquiring and using a plurality of satellite ranging signals having satellite codes to rapidly determine a real time position of a user receiver, the method comprising:

using a first user receiver to receive said satellite codes and to detect therefrom a first-user-receiver probable location;

using the first user receiver to transmit to a second user receiver information and the first user receiver probable location, to limit an Earth-reference search space grid in which the second user receiver is located to predetermined geographic dimensions;

using the first user receiver to transmit a time synch function to the second user receiver to enable the second user receiver to synchronize a user receiver clock, satellite ranging data as received at the first user receiver at an epoch time, including code and carrier phase measurements of the first user receiver at an epoch time;

using the second user receiver to directly predict code phase data and carrier phase data relative to the second user receiver at the epoch time and grid point, and to acquire simultaneously at least one of the satellite codes from a plurality of satellites in view of the first user receiver; and

using the second user receiver to search over the search space grid points and coherently combine received satellite codes from said plurality of satellites and to detect therefrom a second-user-receiver probable location.

24. A method for enabling a user receiver to rapidly acquire and use a plurality of satellite ranging signals having satellite codes to rapidly determine a position of the user receiver, the method comprising:

using a user receiver to receive satellite ranging signals from satellites within view of said user receiver, to determine a first probable location of the user receiver at a first epoch time;

determining a time lapse since the first probable location was detected;

predicting a set of initialization data, using the time lapse, received satellite Navigation message data and first probable location, to limit an Earth-reference search space region to a set of predetermined geographic dimensions;

acquiring simultaneously at least one of the satellite codes from each of the plurality of satellites in view of the user receiver, at a plurality of grid points within the search space region; and

coherently combining said acquired satellite codes at each of said plurality of grid points within said search space region to detect therefrom a second probable location of the user receiver within the Earth-reference search space region at a second epoch time.