Method and apparatus for compensating an oscillator in a location-enabled wireless device

• US 20030176204A1
• Filed: 02/20/2003
• Published: 09/18/2003
• Est. Priority Date: 02/22/2002
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Global Locate Incorporated (Broadcom, Inc.)
• Inventors: Abraham, Charles
• Granted Patent: US 7,010,307 B2
• Time in Patent Office: Days
• US Class Current: 455/556.1
• CPC Class Codes: G01S 19/235 Calibration of receiver components
• CPC Class Codes: H03B 5/04 Modifications of generator to compensate for variations in physical values, e.g. power supply, load, temperature
• CPC Class Codes: H03J 1/0008 using a central processing unit, e.g. a microprocessor digital tuning in general H03J5/0245
• CPC Class Codes: H03J 2200/11 Cellular receiver, e.g. GSM, combined with a GPS receiver
• CPC Class Codes: H03J 3/04 Arrangements for compensating for variations of physical values, e.g. temperature
• CPC Class Codes: H03L 1/025 and a memory for digitally storing correction values
• CPC Class Codes: H03L 1/026 by using a memory for digitally storing correction values H03L1/025 takes precedence
• CPC Class Codes: H04B 1/3805 with built-in auxiliary receivers

Abstract

A method and apparatus for compensating an oscillator in a location-enabled wireless device is described. In an example, a mobile device includes a wireless receiver for receiving wireless signals and a GPS receiver for receiving GPS signals. The mobile device also includes an oscillator having an associated temperature model. A frequency error is derived from a wireless signal. The temperature model is adjusted in response to the frequency error and a temperature proximate the oscillator. Frequency error of the oscillator is compensated using the adjusted temperature model. In another example, a frequency error is derived using a second oscillator within the wireless receiver.

Claims

1. In a mobile device having a wireless receiver for receiving wireless signals and a global positioning system (GPS) receiver for receiving GPS signals, a method of compensating an oscillator having an associated temperature model, the method comprising:

deriving a frequency error from a wireless signal;

sensing a temperature proximate the oscillator;

adjusting the temperature model responsive to the frequency error and the temperature; and

compensating for error in a frequency generated by the oscillator using the adjusted temperature model.

2. The method of claim 1, wherein compensating for error in the frequency generated by the oscillator comprises:

sensing a second temperature proximate the oscillator; and

generating an estimated error in the oscillator responsive to the second temperature and the adjusted temperature model.

3. The method of claim 2, wherein compensating for error in the frequency generated by the oscillator further comprises supplying the estimated error to the GPS receiver.

4. The method of claim 2, wherein compensating for error in the frequency generated by the oscillator further comprises:

adjusting output of the oscillator responsive to the estimated error;

supplying the adjusted output of the oscillator to the GPS receiver.

5. The method of claim 4, wherein the oscillator is a voltage controlled oscillator and adjusting the output of the oscillator comprises:

generating a steering voltage responsive to the second temperature and the adjusted temperature model; and

supplying the steering voltage to the voltage controlled oscillator.

6. The method of claim 1, further comprising:

measuring a reference frequency within the wireless signal;

determining an offset of the reference frequency from a nominal frequency to produce the frequency error; and

updating a portion of the temperature model related to the temperature using the frequency error.

7. The method of claim 6, further comprising:

repeating measuring, determining, and updating to produce a plurality of updated portions of the temperature model; and

fitting the temperature model to the plurality of updated portions of the temperature model.

8. The method of claim 7, further comprising:

dividing the temperature model into a plurality of temperature bands; and

for each of the plurality of temperature bands, discarding older updated portions of the plurality of updated portions in favor of newer updated portions of the plurality of updated portions if a predetermined number of portions within the respective temperature band have been updated.

9. The method of claim 6, wherein measuring the reference frequency comprises receiving a pilot signal from the wireless signal.

10. The method of claim 6, wherein measuring the reference frequency comprises frequency or phase locking to the wireless signal.

11. In a mobile device having a wireless receiver for receiving wireless signals and a global positioning system (GPS) receiver for receiving GPS signals, a method of compensating a first oscillator having an associated temperature model, the method comprising:

compensating for error in a frequency generated by a second oscillator within the wireless receiver to produce a frequency reference signal;

sensing a temperature proximate the first oscillator;

adjusting the temperature model responsive to the frequency reference signal and the temperature; and

compensating for error in a frequency generated by the first oscillator using the adjusted temperature model.

12. The method of claim 11, wherein compensating for error in a frequency generated by the second oscillator comprises:

measuring a reference frequency within the wireless signal;

determining an offset of the reference frequency from a nominal frequency;

compensating for error in the frequency generated by the second oscillator using the offset.

13. The method of claim 12, wherein the second oscillator is a voltage controlled oscillator and compensating for error in the frequency generated by the second oscillator further comprises:

generating a steering voltage responsive to the offset; and

supplying the steering voltage to the voltage controlled oscillator.

14. The method of claim 11, wherein adjusting the temperature model comprises:

comparing the frequency reference signal with output of the first oscillator to provide a frequency error measurement; and

updating a portion of the temperature model related to the temperature using the frequency error measurement.

15. The method of claim 14, wherein adjusting the temperature model further comprises:

repeating comparing and updating to produce a plurality of updated portions of the temperature model; and

fitting the temperature model to the plurality of updated portions of the temperature model.

16. The method of claim 15, wherein adjusting the temperature model further comprises:

dividing the temperature model into a plurality of temperature bands; and

for each of the plurality of temperature bands, discarding older updated portions of the plurality of updated portions in favor of newer updated portions of the plurality of updated portions if a predetermined number of portions within the respective temperature band have been updated.

17. A location-enabled wireless device, comprising:

a wireless receiver for receiving wireless signals;

a global positioning system (GPS) receiver for receiving GPS signals;

an oscillator, coupled to the GPS receiver, having an associated temperature model;

a frequency detector coupled to the wireless receiver, the frequency detector having a wireless signal as an input and a frequency error as an output; and

a processor configured to adjust the temperature model responsive to the frequency error and a temperature proximate the oscillator, and to compensate for error in a frequency generated by the oscillator using the adjusted temperature model.

18. The device of claim 17, wherein the processor is further configured receive a second temperature proximate the oscillator and generate an estimated error signal responsive to the second temperature, the estimated error signal being coupled to the GPS receiver.

19. The device of claim 17, wherein the oscillator is a voltage controlled oscillator and the processor is further configured to receive a second temperature proximate the oscillator and generate a steering voltage responsive to the second temperature, the steering voltage being coupled to the voltage controlled oscillator.

20. The device of claim 17, wherein the frequency detector is a pilot tone frequency detector for detecting a pilot tone in the wireless signal.

21. The device of claim 17, wherein the frequency detector includes a frequency control circuit for frequency or phase locking to the wireless signal.

22. A location-enabled wireless device, comprising:

a wireless receiver for receiving wireless signals;

a global positioning system (GPS) receiver for receiving GPS signals;

a first oscillator, coupled to the GPS receiver, having an associated temperature model;

a second oscillator coupled to the wireless receiver;

a frequency counter coupled to the first oscillator and the second oscillator, the frequency counter having a frequency error as output; and

a processor configured to compensate for error in a frequency generated by the second oscillator, adjust the temperature model responsive to the frequency error and a temperature proximate the first oscillator, and compensate for error in a frequency generated by the first oscillator using the adjusted temperature model.

23. The apparatus of claim 22, wherein the second oscillator is a voltage controlled oscillator and the processor is further configured to generate a steering voltage, the steering voltage being coupled to the voltage controlled oscillator.

24. A mobile device comprising:

a wireless receiver for receiving wireless signals;

a global positioning system (GPS) receiver for receiving GPS signals;

an oscillator, coupled to the GPS receiver, having an oscillator signal as output;

a temperature sensor for sensing a temperature proximate the oscillator;

a frequency detector, coupled to the wireless receiver, having a frequency error as output;

a memory for storing a temperature model associated with the oscillator; and

a processor, coupled to the memory, configured to adjust the temperature model responsive to the frequency error and the temperature, and to compensate for error in a frequency of the oscillator signal using the adjusted temperature model.

25. The mobile device of claim 24, wherein the processor is further configured receive a second temperature proximate the oscillator and generate an estimated error signal responsive to the second temperature, the estimated error signal being coupled to the GPS receiver.

26. The mobile device of claim 24, wherein the oscillator is a voltage controlled oscillator and the processor is further configured to receive a second temperature proximate the oscillator and generate a steering voltage responsive to the second temperature, the steering voltage being coupled to the voltage controlled oscillator.

27. The mobile device of claim 24, wherein the frequency detector is a pilot tone frequency detector for detecting a pilot tone in the wireless signal.

28. The mobile device of claim 24, wherein the frequency detector includes a frequency control circuit for frequency or phase locking to the wireless signal.

29. A mobile device comprising:

a wireless receiver for receiving wireless signals;

a global positioning system (GPS) receiver for receiving GPS signals;

a first oscillator, coupled to the GPS receiver, having an oscillator signal as output;

a second oscillator coupled to the wireless receiver;

a temperature sensor for sensing a temperature proximate the first oscillator;

a frequency counter, coupled to the first oscillator and the second oscillator, the frequency counter having a frequency error as output;

a memory for storing a temperature model associated with the first oscillator; and

a processor, coupled to the memory, configured to compensate for error in a frequency generated by the second oscillator, adjust the temperature model responsive to the frequency error and the temperature, and to compensate for error in a frequency of the oscillator signal using the adjusted temperature model.

30. The mobile device of claim 29, wherein the second oscillator is a voltage controlled oscillator and the processor is further configured to generate a steering voltage, the steering voltage being coupled to the voltage controlled oscillator.