Enhancing Time Keeping Accuracy For Low Power Gps Receivers

• US 20070285309A1
• Filed: 06/30/2004
• Published: 12/13/2007
• Est. Priority Date: 06/30/2004
• Status: Active Grant

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Nokia Corporation
• Inventors: Atkinson, Chris
• Granted Patent: US 7,535,417 B2
• Time in Patent Office: Days
• US Class Current: 342/357.620
• CPC Class Codes: G01S 19/235 Calibration of receiver components
• 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

Abstract

A mobile device including a positioning device for determining position by timing analysis of received signals, the positioning device including a system for determining timing accuracy, the system including first signal generating means for continuously generating a first clock signal whilst the positioning device is inactive, second signal generating means for discontinuously generating a second clock signal during a plurality of spaced apart time periods, and accuracy determining means for determining the accuracy of the first clock signal using timing data from the second clock signal, the positioning device being arranged to determine position by use of the determined timing accuracy of the first clock.

Claims

1. A mobile device comprising a positioning device for determining position by timing analysis of received signals, the positioning device comprising a system for determining timing accuracy, the system comprising:

first signal generating means for continuously generating a first clock signal whilst the positioning device is inactive;

second signal generating means for discontinuously generating a second clock signal during a plurality of spaced apart time periods; and

accuracy determining means for determining the accuracy of the first clock signal using timing data from the second clock signal;

the positioning device being arranged to determine position by use of the determined timing accuracy of the first clock.

2. The mobile device of claim 1 wherein the system comprises first timing circuitry for collecting and storing first timing data relating to the first clock signal only during the plurality of spaced apart time periods.

3. The mobile device of claim 2 wherein the first timing circuitry comprises a first counter for counting clock edges of said first clock signal.

4. The mobile device of claim 3 wherein said first timing data is the cumulative number of clock periods of the first clock signal counted by the first counter during the plurality of spaced apart periods.

5. The mobile device of any claim 4 wherein the system comprises second timing circuitry for collecting and storing second timing data relating to the second clock signal only during the plurality of spaced apart time periods.

6. The mobile device of any claim 5 wherein the second timing circuitry comprises a second counter for counting clock edges of the second clock signal.

7. The mobile device of claim 6 wherein the second timing data is the cumulative number of leading and trailing edges of the second clock signal counted by the second counter during the plurality of spaced apart time periods.

8. The mobile device of any claim 7 wherein the accuracy determining means is arranged to determine an accurate estimate of the length of one period of the first clock signal based on the stored first and second timing data from the first and second counters.

9. The mobile device of claim 7 wherein the system comprises third timing circuitry for continuously collecting and storing third timing data relating to the first clock signal.

10. The mobile device of claim 9 wherein the third timing circuitry comprises a third counter for continuously counting clock edges of the first clock signal.

11. The mobile device of claim 10 wherein the third timing data is the number of clock periods of the first clock signal counted by the third counter.

12. The mobile device of claim 11 wherein when the precise time is known to the positing device, the first, second and third counters are reset, and the precise time is stored in memory.

13. The mobile device of claim 12 wherein the accuracy determining means determines an accurate estimate of the time elapsed since the first, second and third counters were last reset, based on the accurate estimate of the length of one period of the first clock signal, and the third timing data from the third counter.

14. The mobile device of claim 13 wherein the positioning device is arranged to determine the current time based on the precise time stored in memory and the time elapsed since the first, second and third counters were last reset.

15. The mobile device of claim 1 wherein said positioning device is a satellite positioning system device.

16. The mobile device of claim 1 wherein the first clock signal is a sleep clock signal, generated when the mobile device is in a sleep mode of operation.

17. The mobile device of claim 1 wherein the second clock signal is a system clock signal.

18. The mobile device of claim 17 wherein the system clock signal is the system clock used for the communication circuitry in the mobile device.

19. The mobile device of claim 1 wherein the spaced apart time periods are periods in which the mobile device receives paging information from a telecommunications network.

20. The mobile device of claim 19 wherein said telecommunications network is a global system for mobile communications (GSM) network which uses the GSM standard.

21. The mobile device of claim 19 wherein said telecommunications network is a time division multiple access (TDMA) network.

22. The mobile device of claim 19 wherein said telecommunications network is a code-division multiple access (CDMA) network.

23. The mobile device of claim 19 wherein said telecommunications network is a personal digital cellular (PDC) network.