Global positioning apparatus and method for using a temperature compensated oscillator to perform a positon fix

• US 20030128157A1
• Filed: 10/02/2002
• Published: 07/10/2003
• Est. Priority Date: 10/02/2001
• Status: Active Grant

• Current Assignee: CSR Technology Incorporated (Qualcomm, Inc.)
• Original Assignee: SIRF Technology Incorporated (Qualcomm, Inc.)
• Inventors: Salkhi, Amin
• Granted Patent: US 7,148,844 B2
• Time in Patent Office: Days
• US Class Current: 342/357.06
• CPC Class Codes: G01S 19/235 Calibration of receiver components
• CPC Class Codes: G01S 19/27 creating, predicting or correcting ephemeris or almanac data within the receiver
• CPC Class Codes: G01S 19/34 Power consumption

Abstract

A global positioning receiver unit utilizes a temperature compensated oscillator and a unit controller. The temperature compensated oscillator generates a clock signal, and the unit controller is configured to track GPS time based on the clock signal while the receiver unit is in a sleep state. The unit controller is further configured to perform a position fix based on a satellite signal and the GPS time tracked by the unit controller.

Claims

1. A global positioning receiver unit for use in a global positioning system (GPS), comprising:

a temperature compensated oscillator configured to generate a clock signal; and

a unit controller configured to track GPS time based on the clock signal while the receiver unit is in a sleep state, the unit controller further configured to perform a position fix based on a satellite signal and the GPS time tracked by the unit controller.

2. The global positioning receiver unit of claim 1, further comprising:

a first power source for powering the unit controller during an active state; and

a second power source for powering a portion of the unit controller during the sleep state, wherein the unit controller portion is configured to track the GPS time.

3. The global positioning receiver unit of claim 1, wherein the unit controller is configured to determine a value indicative of an amount of time elapsed between a transition of the receiver unit to the sleep state and a transition of the receiver unit to an active state, the unit controller further configured to perform a comparison between the value and a threshold value.

4. The global positioning receiver unit of claim 3, wherein the unit controller is configured to initiate the transition of the receiver unit to the active state based on the comparison.

5. The global positioning receiver unit of claim 1, further comprising a counter configured to receive the clock signal and to output the clock signal at a reduced frequency, the counter further configured to transmit the clock signal, at the reduced frequency, to the unit controller.

6. A global positioning receiver unit for use in a global positioning system (GPS), comprising:

temperature compensated means for generating a clock signal;

means for tracking GPS time based on the clock signal while the receiver unit is in a sleep state;

means for transitioning the receiver unit from the sleep state to an active state;

means for acquiring a satellite signal; and

means for performing a position fix based on the satellite signal and the tracking means.

7. A global positioning receiver unit for use in a global positioning system (GPS), comprising:

a temperature compensated oscillator configured to generate a clock signal; and

a unit controller configured to track GPS time based on the clock signal while the receiver unit is in a sleep state, the unit controller configured to determine a time value indicative of a duration that the receiver unit is in the sleep state, the unit controller configured to perform, if the time value is less than a threshold value, a position fix based on a satellite signal and the GPS time tracked by the unit controller, the unit controller further configured to perform, if the time value exceeds the threshold value, a position fix based on the satellite signal and time data determined from a subframe of the satellite signal.

8. The global positioning receiver unit of claim 7, further comprising a counter configured to receive the clock signal and to output the clock signal at a reduced frequency, the counter further configured to transmit the clock signal, at the reduced frequency, to the unit controller.

9. A global positioning method, comprising:

generating a clock signal via a temperature compensated oscillator within a global positioning receiver unit;

tracking global positioning system (GPS) time based on the clock signal while the receiver unit is in a sleep state;

acquiring a satellite signal; and

performing a position fix based on the satellite signal and the GPS time tracked in the tracking step.

10. The global positioning method of claim 9, further comprising adjusting a frequency of the clock signal.

11. The global positioning method of claim 9, further comprising:

determining a value indicative of an amount of time elapsed between a transition of the receiver unit to the sleep state and a transition of the receiver unit to an active state; and

performing a comparison between the value and a threshold value.

12. The global positioning method of claim 11, wherein the acquiring is performed in response to the comparison.

13. The global positioning method of claim 11, further comprising the initiating the transition of the receiver unit to the active state based on the comparison.

14. A global positioning method for use in a global positioning receiver unit of a global positioning system (GPS), comprising:

generating a clock signal via a temperature compensated oscillator;

maintaining time data based on the clock signal while the receiver unit is in a sleep state, the time data indicative of GPS time;

determining a value indicative of a duration that the receiver unit is in the sleep state;

performing a comparison between the value and a threshold value;

acquiring a satellite signal;

performing a position fix based on the acquired signal; and

determining, based on the comparison, whether to utilize the time data to perform the position fix.

15. The global positioning method of claim 14, further comprising adjusting a frequency of the clock signal, wherein the time data is based on the adjusted frequency.