System and Method for Operating a GPS Device in a Micro Power Mode

• US 20100039316A1
• Filed: 03/30/2009
• Published: 02/18/2010
• Est. Priority Date: 02/25/2008
• Status: Active Grant

• Current Assignee: Qualcomm technologies international, ltd. (Qualcomm, Inc.)
• Original Assignee: SIRF Technology Incorporated (Qualcomm, Inc.)
• Inventors: Leimer, Don K., Kohli, Sanjai, Gronemeyer, Steven A., Sturza, Mark A.
• Granted Patent: US 8,188,917 B2
• Time in Patent Office: Days
• US Class Current: 342/357.480
• CPC Class Codes: G01S 19/235 Calibration of receiver components
• CPC Class Codes: G01S 19/34 Power consumption

Abstract

A wireless device including a transceiver that utilizes a power supply is described. The wireless device includes a Global Positioning System (“GPS”) section having a plurality of GPS subsystems and a power controller in signal communication with the power supply and GPS section, wherein the power controller is configured to selectively power each GPS subsystem from the plurality of GPS subsystems.

Claims

1. A wireless device including a transceiver that utilizes a power supply, the wireless device comprising:

a Global Positioning System (“

GPS”

) section having a plurality of GPS subsystems; and

a power controller in signal communication with the power supply and GPS section, wherein the power controller is configured to selectively power each GPS subsystem from the plurality of GPS subsystems in response to receiving an input power control signal.

2. The wireless device of claim 1, wherein the plurality of GPS subsystems includes

at least one RF GPS subsystem,

a baseband GPS subsystem, and

a processor GPS subsystem and

wherein the power controller is configured to turn off the at least one RF GPS subsystem in response to receiving the input power control signal.

3. The wireless device of claim 2, wherein the input power control signal is produced by a component selected from the group consisting of the GPS section, a transceiver, a temperature sensor, and a motion sensor.

4. The wireless device of claim 3, wherein the input power control signal is produced by the transceiver and the input power control signal is an RSSI measurement signal or a Doppler measurement signal.

5. The wireless device of claim 3, wherein the input power control signal is produced by the GPS section and includes velocity measurements from the GPS section.

6. The wireless device of claim 3, wherein the GPS section is configured to operate as a timing receiver when the wireless device is in a weak signal environment, and wherein the GPS section is configured to assume that the wireless device is in a static position and to verify that assumption that the wireless device is in a static position whenever the GPS section is capable of performing measurements in the weak signal environment.

7. The wireless device of claim 3, wherein the GPS section is configured to manage time and frequency uncertainties so as to minimize the need for bit synchronization, frame synchronization, or both.

8. The wireless device of claim 7, wherein the GPS section is configured to operate in a low-power mode that wakes up only to the extent necessary to keep the time uncertainty to within ±

¼

of a coarse/acquisition (“

C/A”

) code period.

9. The wireless device of claim 3, wherein the GPS section is capable of operating in a low-power mode that wakes up occasionally to capture a relatively short sequence of RF sample data.

10. The wireless device of claim 9, wherein the GPS sampling is capable of being adapted based on cellular RSSI measurements.

11. The wireless device of claim 9, further including a real-time clock (“

RTC”

).

12. The wireless device of claim 11, wherein the RTC is configured to run at 32,768 Hz.

13. The wireless device of claim 11, wherein the GPS section is configured to capture data that is synchronized to predictable data segments.

14. The wireless device of claim 13, wherein the predictable data segments are data bits from synchronized bit segments of telemetry data (“

TLM”

) or predictable time of the week (“

TOW”

) bit segments of hand-over-word (“

HOW”

) words of data.

15. The wireless device of claim 14, wherein GPS section is configured to utilize longer coherent integration that utilizes data stripping to enable measurements of GPS signal data at lower signal levels.

16. The wireless device of claim 9, wherein the power controller is capable of turning off the at least one RF GPS subsystem in response to the GPS section receiving GPS samples that are processed by the baseband GPS subsystem.

17. The wireless device of claim 3, further including a real-time clock (“

RTC”

) that has a frequency error as a function of temperature.

18. The wireless device of claim 17, wherein the GPS section is configured to receive GPS samples that have a GPS sampling interval frequency that is adaptive.

19. The wireless device of claim 18, wherein the GPS sampling interval frequency is adaptive based on an observed clock frequency of the RTC.

20. The wireless device of claim 19, wherein GPS sampling interval frequency is adapted based on a rate of change of an observed RTC clock frequency based on a previous observed RTC clock frequency sample.

21. The wireless device of claim 3, wherein the power controller is further configured to receive an input power control signal from the motion sensor and wherein the GPS sampling has a duty cycle that is reduced whenever the wireless device is stationary.

23. The wireless device of claim 3, wherein RSSI measurements are utilized to determine that the wireless device is stationary.

24. The wireless device of claim 23, wherein Doppler shift measurements are utilized to determine that the wireless device is stationary.

25. The wireless device of claim 23, wherein the duty cycle is reduced when the wireless device is moving slower than a predetermined threshold.

26. The wireless device of claim 25, wherein predetermined threshold is 10 miles per hour.

27. The wireless device of claim 3, wherein the wireless device includes a transceiver type chosen from a group consisting of a cellular transceiver, Wi-Fi transceiver, Wi-Max transceiver, and satellite transceiver.

28. The wireless device of claim 1, wherein the wireless device is a type of wireless device chosen from a group consisting of is a notebook computer, cordless telephone handset, satellite telephone handset, voice-over Internet protocol (“

VoIP”

) handset, and cellular handset.

29. The wireless device of claim 11, wherein the RTC has a time value and frequency value and wherein the GPS section is configured to update the time and frequency values based on a signal from a Temperature Controlled Crystal Oscillator (“

TCXO”

) that has a TCXO frequency when no GPS signal measurement is possible.

30. The wireless device of claim 29, wherein the RTC frequency is updated based on a ratio of the RTC to TCXO, where the TCXO frequency is the last value calibrated from GPS measurement.

31. The wireless device of claim 30, wherein the current RTC time bias relative to GPS time is updated based on an average between the current RTC frequency and the previous RTC frequency update.

32. The wireless device of claim 30, wherein the GPS section is configured to calibrate the TCXO utilizing a folded calibration of the ratio of the RTC to TCXO versus a TCXO frequency error.

33. The wireless device of claim 32, wherein the folded calibration utilizes a conventional ratio counter or an edge aligned ratio counter.

34. The wireless device of claim 32, wherein the RTC has a frequency error as a function of temperature and the GPS section is configured to calibrate the RTC frequency error based on temperature measurements produced by the temperature sensor.

35. The wireless device of claim 32, wherein the GPS section is configured to adaptively change the interval of the update time based on the estimated temperature and the change of temperature.

36. The wireless device of claim 34, wherein the TCXO frequency error versus temperature is calibrated based on temperature data produced by the temperature sensor.

37. The wireless device of claim 9, wherein the GPS section is configured to adjust search uncertainty by processing a capture buffer located within the GPS section.

38. The wireless device of claim 37, where use of cross satellite non-coherent combining with different range correction is utilized to reduce the detection threshold in a timing receiver mode.

39. The wireless device of claim 9, wherein the GPS section is configured to avoid performing data collection as long as extended ephemeris (“

EE”

) is available of a received GPS satellite.

40. The wireless device of claim 39, wherein the GPS section is configured to download EE from a network in signal communication with the wireless device.

41. The wireless device of claim 39, wherein the GPS section is configured to calculate the EE.

42. The wireless device of claim 9, wherein the GPS section is configured to avoid performing data collection when the GPS section is capable of calibrating a new GPS satellite utilizing a range and drift for the new GPS satellite based on almanac and a current time and a position hypothesis.

43. A power controller utilized in a wireless device having a Global Positioning System (“

GPS”

) section having a plurality of GPS subsystems, the power controller comprising;

a first input capable of receiving an input power signal from a power source within the wireless device;

an second input capable of receiving an input power control signal;

a plurality of outputs, wherein each output from the plurality of outputs is capable of being in signal communication with a corresponding GPS subsystem from the plurality of GPS subsystems; and

a controller capable of both selecting each output from the plurality of outputs and sending a power signal from the selected output to the corresponding GPS subsystem.

44. The power controller of claim 43, wherein the plurality of GPS subsystems includes

at least one RF GPS subsystem,

a baseband GPS subsystem, and

a processor GPS subsystem and

wherein the power controller is configured to turn off the at least one RF GPS subsystem in response to receiving the input power control signal.

45. The power controller of claim 44, wherein the input power control signal is produced by a component selected from the group consisting of the GPS section, a transceiver, a temperature sensor, and a motion sensor.

46. The power controller of claim 45, wherein the input power control signal is produced by the transceiver and the input power control signal is an RSSI measurement signal or a Doppler measurement signal.

47. The power controller of claim 45, wherein the input power control signal is produced by the GPS section and includes velocity measurements from the GPS section.

50. A method for operating a Global Positioning System (“

GPS”

) section, within a wireless device, in a micro-power mode (“

MPM”

), where the GPS section has a plurality of GPS subsystems, the method comprising;

receiving an input power control signal; and

selectively powering each GPS subsystem within the plurality of GPS subsystems in response to receiving the measurement signal based on a set of rules.

51. The method of claim 50, wherein the input power control signal is produced by a component selected from the group consisting of the GPS section, a transceiver, a temperature sensor, and a motion sensor.

52. The method of claim 51, wherein the input power control signal is produced by the transceiver and the input power control signal is an RSSI measurement signal or a Doppler measurement signal.

53. The method of claim 51, wherein the input power control signal is produced by the GPS section and includes velocity measurements from the GPS section.

54. The method of claim 52, further including operating the GPS section as a timing receiver when the wireless device is in a weak signal environment, and

wherein operating as a timing receiver includes

assuming that the wireless device is in a static position and

verifying the assumption that the wireless device is in a static position whenever the GPS section is capable of performing measurements in the weak signal environment.

56. The method of claim 52, further including managing time and frequency uncertainties so as to minimize the need for bit synchronization, frame synchronization, or both.

57. The method of claim 56, further including operating in a low-power mode that wakes up only to the extent necessary to keep the time uncertainty to within ±

¼

of a coarse/acquisition (“

C/A”

) code period.

58. The method of claim 57, further including operating in a low-power mode that wakes up occasionally to capture a relatively short sequence of RF sample data.

59. The method of claim 58, further including GPS sampling adaptively based on cellular RSSI measurements.

60. The method of claim 52, further including capturing data that is synchronized to predictable data segments.

61. The method of claim 60, further including utilizing longer coherent integration that utilizes data stripping to enable measurements of GPS signal data at lower signal levels.