Always-on satellite positioning receiver

• US 7,375,682 B1
• Filed: 12/20/2006
• Issued: 05/20/2008
• Est. Priority Date: 12/20/2006
• Status: Active Grant

• Current Assignee: U-Blox AG (u-blox Holding AG)
• Original Assignee: AIR Semiconductor Ltd.
• Inventors: Tester, David P., Graham, Stephen P.
• Primary Examiner(s): PHAN, DAO LINDA
• Application Number:
  US11/613,219
• Time in Patent Office: 517 Days
• Field of Search: 342/357.05, 342/357.06, 342/357.08, 342/357.12, 701/213, 701/215
• US Class Current: 342/357.63
• CPC Class Codes: G01S 19/24 Acquisition or tracking or demodulation of signals transmitted by the system synchronisation aspects of direct sequence spread spectrum modulation H04B1/7073
• CPC Class Codes: G01S 19/29 carrier including Doppler, related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/34 Power consumption
• CPC Class Codes: G01S 19/37 Hardware or software details of the signal processing chain

Abstract

A method for establishing a position of a device is disclosed. The method generally includes the steps of (A) receiving an input signal from a receiver listening to a plurality of satellites in a positioning system, (B) calculating (i) a plurality of estimated Doppler shifts of the satellites, (ii) an estimated position of the device and (iii) an estimated velocity of the device, (C) generating a plurality of pseudo-ranges in an intermediate signal based on all of (i) the input signal, (ii) the estimated Doppler shifts, (iii) the estimated position and (iv) the estimated velocity and (D) generating the position in an output signal based on the pseudo-ranges.

Claims

1. A method for establishing a position of a device, comprising the steps of:

(A) receiving an input signal from a receiver listening to a plurality of satellites in a positioning system;

(B) calculating (i) a plurality of estimated Doppler shifts of said satellites, (ii) an estimated position of said device and (iii) an estimated velocity of said device;

(C) calculating a plurality of estimated locations of a plurality of pseudo-random code sequences in said input signal based on all of (i) said estimated position of said device and (ii) said estimated velocity of said device;

(D) generating a plurality of pseudo-ranges in an intermediate signal based on said estimated locations; and

(E) generating said position in an output signal based on said pseudo-ranges.

2. The method according to claim 1, wherein step (D) further comprises the sub-step of:

tracking said pseudo-random code sequences by performing a plurality of limited searches in both time and frequency approximate said estimated locations.

3. The method according to claim 1, wherein said estimated locations are calculated for at most six of said satellites.

4. The method according to claim 1, wherein said calculation of said estimated locations of said pseudo-random code sequences continues while said pseudo-random code sequences are unsuitable to track.

5. The method according to claim 1, further comprising the step of:

reporting a sequence of estimated values for said position in said output signal while said pseudo-random code sequences are unsuitable to track.

6. The method according to claim 1, further comprising the step of:

calculating both (i) said estimated position of said device and (ii) said estimated velocity of said device based on (a) a previous position of said device and (b) a previous velocity of said device.

8. The method according to claim 1, further comprising the step of:

generating said position using a fast acquisition technique in response to at least one of (i) a power up of said device and (ii) a command to quickly establish said position from an unknown state.

9. The method according to claim 8, further comprising the step of:

reducing a power consumed by said fast acquisition technique after said position has been determined at least once.

10. The method according to claim 1, wherein said position is generated from at most four of said satellites.

11. The method according to claim 10, wherein said at most four satellites are a combination of said satellites heard by said receiver that results in a best geometric dilution of precision metric.

7. A method for establishing a position of a device, comprising the steps of:

(A) receiving an input signal from a receiver listening to a plurality of satellites in a positioning system;

(B) calculating (i) a plurality of estimated Doppler shifts of said satellites, (ii) an estimated position of said device and (iii) an estimated velocity of said device;

(C) generating a plurality of pseudo-ranges in an intermediate signal based on all of (i) said input signal, (ii) said estimated Doppler shifts, (iii) said estimated position and (iv) said estimated velocity;

(D) generating said position in an output signal based on said pseudo-ranges; and

(E) reducing a power consumed by said receiver between updates of said position.

12. A device comprising:

a tracking engine configured to (i) receive an input signal from a receiver listening to a plurality of satellites in a positioning system, (ii) calculate a plurality of estimated Doppler shifts of said satellites and (iii) calculate a plurality of estimated locations of a plurality of pseudo-random code sequences in said input signal based on all of (a) an estimated position of said device and (b) an estimated velocity of said device and (iv) generate a plurality of pseudo-ranges in an intermediate signal based on said estimated locations; and

a position calculator co-located with said tracking engine and configured to generate (i) said estimated position, (ii) said estimated velocity and (iii) said position in an output signal based on said pseudo-ranges.

13. The device according to claim 12, wherein said tracking engine is further configured to (i) calculate said estimated locations of said pseudo-random code sequences while said pseudo-random code sequences are unsuitable to track.

14. The device according to claim 12, further comprising a fast acquisition engine configured to establish said position in response to at least one of (i) a power up of said device and (ii) a command to quickly establish said position from an unknown state.

15. The device according to claim 14, further comprising a power controller configured to reduce a power consumption of said fast acquisition engine after establishing said position at least once.

16. The device according to claim 12, wherein said device comprises at least one of (i) a cell phone, (ii) a laptop computer, (iii) a palm computer, (iv) a personal digital assistant and (v) a heads-up display.

18. The device according to claim 12, further comprising a power controller configured to reduce a power consumed by said receiver between updates in said position.

19. The device according to claim 12, wherein said position circuit is further configured to report a sequence of estimated values for said position in said output signal while said pseudo-random code sequences are unsuitable to track.

20. The device according to claim 12, wherein said estimated locations are calculated for at most six of said satellites.

17. A device comprising:

means for (i) receiving an input signal from a receiver listening to a plurality of satellites in a positioning system, (ii) calculating a plurality of estimated Doppler shifts of said satellites and (iii) calculating a plurality of estimated locations of a plurality of pseudo-random code sequences in said input signal based on all of (a) an estimated position of said device and (b) an estimated velocity of said device and (iv) generating a plurality of pseudo-ranges in an intermediate signal based on said estimated locations; and

means for generating (i) said estimated position, (ii) said estimated velocity and (iii) said position in an output signal based on said pseudo-ranges, said means for generating being co-located with said means for calculating said estimated Doppler shifts.