Method and apparatus for enhanced autonomous GPS

• US 20050212700A1
• Filed: 02/11/2005
• Published: 09/29/2005
• Est. Priority Date: 10/02/2002
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Global Locate Incorporated (Broadcom, Inc.)
• Inventors: Podshivalov, Sergei, Abraham, Charles, Diggelen, Frank Van
• Granted Patent: US 7,595,752 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 19/06 employing an initial estimate of the location of the receiver as aiding data or in generating aiding data
• CPC Class Codes: G01S 19/252 Employing an initial estimate of location in generating assistance data
• 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 19/258 relating to the satellite constellation, e.g. almanac, ephemeris data, lists of satellites in view
• CPC Class Codes: G01S 19/27 creating, predicting or correcting ephemeris or almanac data within the receiver
• CPC Class Codes: G01S 19/42 Determining position

Abstract

Method and apparatus for locating position of a remote receiver is described. In one example, long term satellite tracking data is obtained at a remote receiver. Satellite positioning system (SPS) satellites are detected. Pseudoranges are determined from the remote receiver to the detected SPS satellites. Position of the remote receiver is computed using the pseudoranges and the long term satellite tracking data. SPS satellites may be detected using at least one of acquisition assistance data computed using a previously computed position and a blind search. Use of long term satellite tracking data obviates the need for the remote receiver to decode ephemeris from the satellites. In addition, position of the remote receiver is computed without obtaining an initial position estimate from a server or network.

Claims

1. A method of locating position of a remote receiver, comprising:

obtaining long term satellite tracking data at said remote receiver;

detecting satellite positioning system (SPS) satellites;

determining pseudoranges from said remote receiver to said detected SPS satellites; and

computing position of said remote receiver using said pseudoranges and said long term satellite tracking data.

2. The method of claim 1, wherein said step of detecting comprises at least one of:

using acquisition assistance data computed using a previously computed position to detect said SPS satellites; and

performing a blind search to detect said SPS satellites.

3. The method of claim 1, wherein said long term satellite tracking data is received at said remote receiver from a server.

4. The method of claim 1, wherein said long term satellite tracking data is generated by said remote receiver.

5. The method of claim 1, wherein said step of determining pseudoranges comprises:

measuring sub-millisecond pseudoranges to said detected SPS satellites;

decoding a time-of-week (TOW) value transmitted by at least one of said detected SPS satellites; and

resolving integer-millisecond portions of said sub-millisecond pseudoranges to produce said pseudoranges using said TOW value.

6. The method of claim 1, wherein said step of determining pseudoranges comprises:

measuring sub-millisecond pseudoranges to said detected SPS satellites;

measuring pseudorange rates with respect to said detected SPS satellites;

calculating a position estimate of said remote receiver using said pseudorange rates; and

resolving integer-millisecond portions of said sub-millisecond pseudoranges using said position estimate to produce said pseudoranges.

7. The method of claim 6, wherein said step of computing comprises:

obtaining a time-of-day estimate;

relating said sub-millisecond pseudoranges to a plurality of position and time variables using said long term satellite tracking data, said time-of-day estimate, and said position estimate; and

solving for one or more of said position and time variables to determine said position.

8. The method of claim 1, wherein said step of determining pseudoranges comprises:

measuring sub-millisecond pseudoranges to said detected SPS satellites;

selecting an a-priori position from a position space; and

resolving integer-millisecond portions of said sub-millisecond pseudoranges using said a-priori position to produce said pseudoranges.

9. The method of claim 8, wherein said step of computing comprises:

obtaining a time-of-day estimate;

relating said sub-millisecond pseudoranges to a plurality of position and time variables using said long term satellite tracking data, said time-of-day estimate, and said a-priori position; and

solving for one or more of said position and time variables to determine said position.

10. The method of claim 8, further comprising:

repeating said steps of selecting and resolving for at least one additional a-priori position of said position space in response to a determination that said position is invalid.

11. A method of locating position of a remote receiver, comprising:

obtaining long term satellite tracking data at said remote receiver;

measuring sub-millisecond pseudoranges to a first plurality of SPS satellites;

measuring pseudorange rates with respect to a second plurality SPS satellites;

calculating a position estimate of said remote receiver using said pseudorange rates;

resolving integer-millisecond portions of said sub-millisecond pseudoranges using said position estimate to produce full pseudoranges; and

computing position of said remote receiver using said full pseudoranges and said long term satellite tracking data.

12. The method of claim 11, wherein said step of computing comprises:

determining whether precise time-of-day is available;

calculating said position using a time-free navigation model in response to said precise time-of-day being unavailable.

13. The method of claim 12, wherein said step of calculating comprises:

obtaining a time-of-day estimate;

relating said sub-millisecond pseudoranges to a plurality of position and time variables using said long term satellite tracking data, said time-of-day estimate, and said position estimate; and

solving for one or more of said position and time variables to determine said position.

14. Apparatus for locating position, comprising:

a memory for storing long term satellite tracking data;

a satellite signal receiver for detecting satellite positioning system (SPS) satellites and determining pseudoranges to said detected SPS satellites; and

a processor for computing position using said pseudoranges and said long term satellite tracking data.

15. The apparatus of claim 14, wherein said satellite signal receiver is configured to detect said SPS satellites using at least one of:

a) acquisition assistance data computed using a previously computed position; and

b) a blind search.

16. The apparatus of claim 14, further comprising:

a communications transceiver for receiving said long term satellite tracking data from a server.

17. The apparatus of claim 14, wherein said satellite signal receiver is configured to:

measure sub-millisecond pseudoranges to said detected SPS satellites;

decode a time-of-week (TOW) value transmitted by at least one of said detected SPS satellites; and

resolve integer-millisecond portions of said sub-millisecond pseudoranges to produce said pseudoranges using said TOW value.

18. The apparatus of claim 14, wherein said satellite signal receiver is configured to:

measure sub-millisecond pseudoranges to at least one of said detected SPS satellites;

measure pseudorange rates with respect to at least one of said detected SPS satellites;

calculate a position estimate of said remote receiver using said pseudorange rates; and

resolve integer-millisecond portions of said sub-millisecond pseudoranges using said position estimate to produce said pseudoranges.

19. The apparatus of claim 18, wherein said processor is configured to:

obtain a time-of-day estimate;

relate said sub-millisecond pseudoranges to a plurality of position and time variables using said long term satellite tracking data, said time-of-day estimate, and said position estimate; and

solve for one or more of said position and time variables to determine said position.

20. The apparatus of claim 14, wherein said satellite signal receiver is configured to:

measure sub-millisecond pseudoranges to said detected SPS satellites;

select an a-priori position from a position space; and

resolve integer-millisecond portions of said sub-millisecond pseudoranges using said a-priori position to produce said pseudoranges.

21. The apparatus of claim 20, wherein said processor is configured to:

obtain a time-of-day estimate;

relate said sub-millisecond pseudoranges to a plurality of position and time variables using said long term satellite tracking data, said time-of-day estimate, and said a-priori position; and

solve for one or more of said position and time variables to determine said position.