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

• US 7,010,307 B2
• Filed: 02/20/2003
• Issued: 03/07/2006
• 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
• Primary Examiner(s): D AGOSTA, STEPHEN M
• Application Number:
  US10/372,015
• Publication Number:
  US 20030176204A1
• Time in Patent Office: 1,111 Days
• Field of Search: 455/255, 455/264, 455/265, 455/456.1, 455/553.1, 331/158, 331/176, 342/357.1, 342/357.6, 342/357.12
• US Class Current: 455/456.1
• 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 output frequency of an oscillator having an associated temperature model, the method comprising:

measuring a reference frequency within a wireless signal;

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

sensing a temperature proximate the oscillator;

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

compensating for error in the output frequency generated by the oscillator using the adjusted temperature model;

supplying the frequency error and the output frequency of the oscillator to the GPS receiver, where the GPS receiver uses the frequency error and the output frequency to process satellite signals;

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.

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

adjusting output frequency of the oscillator responsive to the frequency error;

supplying the adjusted output frequency 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 frequency 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, wherein measuring the reference frequency comprises receiving a pilot signal from the wireless signal.

7. The method of claim 1, wherein measuring the reference frequency comprises frequency or phase locking to the wireless signal.

8. 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 by;

measuring a reference frequency within a wireless signal; and

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

sensing a temperature proximate the oscillator;

adjusting the temperature model responsive to the frequency error and the temperature by updating a portion of the temperature model related to the temperature using the frequency error;

compensating for error in an output frequency generated by the oscillator using the adjusted temperature model;

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

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

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. 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:

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 a second oscillator using the offsets generating a steering voltage responsive to the offsets and supplying the steering voltage to the second oscillator;

sensing a temperature proximate the first oscillator;

adjusting the temperature model responsive to the offset and the temperature;

compensating for error in a output frequency generated by the first oscillator using the adjusted temperature model; and

supplying the offset and the output frequency of the first oscillator to the GPS receiver, where the GPS receiver uses the offset and the output frequency of the first oscillator to process satellite signals.

10. The method of claim 9, wherein adjusting the temperature model comprises:

comparing the offset with the output frequency 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.

11. The method of claim 10, 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.

12. 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;

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;

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

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

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; and

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

13. 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 voltage-controlled 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 voltage-controlled oscillator, the frequency counter having a frequency error as an 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 voltage-controlled oscillator, generate a steering voltage, the steering voltage being coupled to the voltage controlled 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 where the frequency error and the frequency of the first oscillator are coupled to the GPS receiver and used to process satellite signals.