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

• US 7,239,857 B2
• Filed: 12/19/2005
• Issued: 07/03/2007
• Est. Priority Date: 02/22/2002
• Status: Expired due to Fees

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Global Locate Incorporated (Broadcom, Inc.)
• Inventors: Abraham, Charles
• Primary Examiner(s): D AGOSTA, STEPHEN M
• Application Number:
  US11/311,088
• Publication Number:
  US 20060094465A1
• Time in Patent Office: 561 Days
• Field of Search: 455/255, 455/264, 455/265, 4554561-457, 455/553.1, 342/357.1, 342/357.6, 342/357.12, 331/158, 331/176
• US Class Current: 455/255
• 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 satellite signals, wherein the mobile device includes an oscillator for providing first and second oscillator signals for use with the wireless receiver, a method of providing to the GPS receiver reference information for processing the satellite signals, the method comprising:

obtaining the first oscillator signal;

sensing a first temperature proximate to the oscillator;

obtaining, from a temperature model of the oscillator, an oscillator-signal error, wherein the oscillator-signal error is a function of a comparison between frequencies of a wireless signal and the second oscillator signal, and wherein the comparison comprises;

obtaining the wireless and second oscillator signals;

sensing a second temperature proximate to the oscillator;

comparing the frequencies of the wireless and second oscillator signals so as to produce a frequency error; and

adjusting the temperature model as a function of the frequency error and the temperature; and

providing to the GPS receiver the oscillator-signal error and the first oscillator signal, wherein the GPS receiver is operable to process satellite signals using the oscillator-signal error and the first oscillator signal.

2. The method of claim 1, wherein comparing the frequencies of the wireless and second oscillator signals so as to produce the frequency error comprises:

(i) measuring a reference frequency associated with the wireless signal; and

(ii) determining an offset, wherein the offset is a difference between frequencies of the reference frequency and a nominal frequency of the second oscillator signal, and wherein adjusting the temperature model as a function of the second frequency error and the second temperature comprises;

using the second frequency error to update a portion of the temperature model that is associated with the first temperature.

3. In a mobile device having a wireless receiver for receiving wireless signals and a global positioning system (GPS) receiver for receiving satellite signals, wherein the mobile device includes an oscillator for providing first and second oscillator signals for use with the wireless receiver, a method of providing to the GPS receiver reference information for processing the satellite signals, the method comprising:

obtaining the first oscillator signal;

sensing a first temperature proximate to the oscillator;

obtaining, from a temperature model of the oscillator, an oscillator-signal error, wherein the oscillator-signal error is a function of a comparison between frequencies of a first wireless signal and the second oscillator signal; and

providing to the GPS receiver the oscillator-signal error and the first oscillator signal, wherein the GPS receiver is operable to process satellite signals using the oscillator-signal error and the first oscillator signal;

obtaining a second wireless signal and a third oscillator signal;

sensing a second temperature proximate to the oscillator;

comparing frequencies of the second wireless signal and the third oscillator signal so as to produce a second frequency error; and

adjusting the temperature model as a function of the second frequency error and the second temperature so as to produce an adjusted temperature model.

4. The method of claim 3, further comprising using the adjusted temperature model to compensate for error in a fourth oscillator signal so as to produce a compensated oscillator signal.

5. The method of claim 4, wherein compensating using the adjusted temperature model to compensate for error in a fourth oscillator signal comprises adjusting, as function of the second frequency error, an output frequency of the oscillator.

6. The method of claim 4, further comprising providing to the GPS receiver the compensated oscillator signal, wherein the GPS receiver is operable to process satellite signals using the compensated oscillator signal.

7. The method of claim 3, further comprising:

obtaining a fourth oscillator signal;

obtaining from the adjusted temperature model a second oscillator-signal error; and

providing to the GPS receiver the second oscillator-signal error and the fourth oscillator signal, wherein the GPS receiver is operable to process satellite signals using the second oscillator-signal error and the fourth oscillator signal.

8. A location-enabled wireless device, comprising:

a wireless receiver operable to receive a first wireless signal;

a global positioning system (GPS) receiver operable to receive a GPS signal;

an oscillator operable to supply to the wireless and GPS receivers a first oscillator signal;

a temperature model for compensating the first oscillator signal as a function of temperature;

a frequency detector operable to supply, as a function of the first wireless signal and the first oscillator signal, a frequency error; and

a processor operable to (i) obtain a temperature proximate to the oscillator;

(ii) obtain from the frequency detector the frequency error;

(iii) use the temperature model to produce, as a function of the temperature and the frequency error, an oscillator-signal error; and

(iv) provide to the GPS receiver the oscillator-signal error, wherein the GPS receiver is operable to use the oscillator-signal error and the first oscillator signal to process satellite signals, wherein the oscillator-signal error comprises an error associated with the temperature and a comparison between frequencies of a second wireless signal and a second oscillator signal, and wherein the second wireless signal and the second oscillator signal are obtained prior to the first wireless signal and the first oscillator signal.

9. The device of claim 8, further comprising memory operable to store the temperature model, wherein the memory is coupled and operable to exchange with the processor information associated the temperature model.

10. The device of claim 8, wherein the processor is further operable to adjust the temperature model as a function of the temperature and the frequency error.

11. The device of claim 8, wherein the oscillator is a voltage-controlled oscillator, wherein the processor is further operable to generate, as a function of the temperature, a steering voltage for steering the voltage-controlled oscillator, and wherein the oscillator-signal error comprises the steering voltage.

12. A location-enabled wireless device, comprising:

a wireless receiver operable to receive a first wireless signal;

a global positioning system (GPS) receiver operable to receive a GPS signal;

a first oscillator operable to supply to the GPS receiver first and third oscillator signals, wherein the first oscillator is operable to provide the third oscillator signal prior to providing the first oscillator signal;

a second oscillator operable to supply to the wireless receiver second and fourth oscillator signals, wherein the second oscillator is operable to provide the fourth oscillator signal prior to providing the second oscillator signal;

a temperature model for compensating the first oscillator signal as a function of temperature;

a frequency counter operable to supply a first reference signal, wherein the first reference signal is a function of a comparison between the first and second oscillator signals; and

a processor operable to (i) obtain a temperature proximate to the first oscillator;

(ii) obtain from the frequency counter the reference signal;

(iii) use the temperature model to produce, as a function of the temperature and the reference signal, an oscillator-signal error; and

(iv) provide to the GPS receiver the oscillator-signal error, wherein the GPS receiver is operable to use the oscillator-signal error and the first oscillator signal to process satellite signals, wherein the oscillator-signal error comprises an error associated with the temperature and a second reference signal, and wherein the second reference signal is a function of a comparison between frequencies of third and fourth oscillator signals.

13. The device of claim 12, wherein the processor is further operable to adjust the temperature model as a function of the temperature and the first reference signal.

14. The device of claim 13, wherein

the first and second oscillators are further operable to provide third and fourth oscillator signals, respectively,

the frequency counter is further operable to supply, as a function of the third and fourth oscillator signals, a second reference signal,

the temperature model is divisible into at least first and second temperature bands,

each of the first and second temperature bands comprise a respective plurality of portions,

each of the plurality of portions include a new portion and an old portion, and

the processor is further operable to:

(i) use the first reference signal to (a) update the new portion of the first temperature band, and (b) discard the old portion of the first temperature band in favor of the new portion of the first temperature band if a predetermined number of the plurality of portions of the first temperature band have been updated; and

(ii) use the second reference signal to (a) update the new portion of the second temperature band, and (b) discard the old portion of the second temperature band in favor of the new portion of the second temperature band if a predetermined number of the plurality of portions of the second temperature band have been updated.

15. The device of claim 12, further comprising memory operable to store the temperature model, wherein the memory is coupled to and operable to exchange with the processor information associated the temperature model.

16. The device of claim 12, wherein the first and second oscillators are further operable to provide third and fourth oscillator signals, respectively, wherein the frequency counter is further operable to supply, as a function of the third and fourth oscillator signals, a second reference signal;

and wherein the processor is further operable to (i) obtain a second temperature proximate to the first oscillator;

(ii) obtain from the frequency counter the second reference signal; and

(iii) adjust the temperature model as a function of the second temperature and the second reference signal.

17. The device of claim 16, wherein the processor is further operable to (i) use the temperature model to produce, as a function of the second temperature and the second reference signal, a second oscillator-error signal, and (ii) provide to the GPS receiver the second oscillator-signal error, and wherein the GPS receiver is operable to use the second oscillator-signal error and the second oscillator signal to process satellite signals.