Method and apparatus for adjusting reference oscillator frequency in a mobile wireless device

• US 20060276223A1
• Filed: 08/16/2006
• Published: 12/07/2006
• Est. Priority Date: 01/16/2003
• 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 7,848,778 B2
• Time in Patent Office: Days
• US Class Current: 455/556.100
• CPC Class Codes: G01S 19/235 Calibration of receiver components
• CPC Class Codes: H03J 2200/11 Cellular receiver, e.g. GSM, combined with a GPS receiver
• CPC Class Codes: H03J 7/04 where the frequency control is accomplished by varying the electrical characteristics of a non-mechanically adjustable element or where the nature of the frequency controlling element is not significant
• CPC Class Codes: H04B 1/3805 with built-in auxiliary receivers
• CPC Class Codes: H04B 1/403 using the same oscillator for generating both the transmitter frequency and the receiver local oscillator frequency

Abstract

A method and apparatus for using a conventional oscillator in a cellular telephone transceiver as a source of a reference signal for a GPS receiver. In one embodiment, the method comprises using a voltage-controlled oscillator (“VCXO”) within a cellular telephone transceiver to generate a reference frequency signal for the GPS receiver. Circuitry within the telephone transceiver generates a frequency error signal. Both of these signals are coupled to GPS circuitry and used to control a carrier numerically controlled oscillator (“NCO”) and a code NCO. The NCOs produce a tuning signal and a timing signal, respectively. The GPS circuitry uses the NCO generated signals to process GPS signals.

Claims

1. Apparatus within an integrated mobile device comprising:

cell phone circuitry for generating of an oscillator signal and a frequency error signal;

a controller, coupled to the cell phone circuitry, for processing the frequency error signal to produce a frequency control value;

a carrier numerically controlled oscillator, within GPS circuitry, for generating a carrier tuning oscillator signal in response to the oscillator signal and the frequency control value signal; and

a code numerically controlled oscillator, within GPS circuitry, for generating a code timing oscillator signal in response to the oscillator signal and the frequency control value.

2. The apparatus of claim 1, wherein the cell phone circuitry comprises a voltage controlled crystal oscillator for generating the oscillator signal.

3. The apparatus of claim 1, wherein the GPS circuitry comprises assisted GPS circuitry.

4. The apparatus of claim 1, wherein the frequency control value is a digital word.

5. The apparatus of claim 1, wherein the cell phone circuitry further comprises a digital signal processor for generating the frequency error signal and supplying the frequency error signal to the controller.

6. The apparatus of claim 1, wherein the cell phone circuitry further comprises a memory for storing frequency control software for adjusting the frequency of the voltage controlled oscillator under the control of the controller.

7. The apparatus of claim 1, further comprising within the GPS circuitry at least one processing channel coupled to an analog-to-digital converter, wherein the at least one processing channel is adjusted by a tuner under a control of the carrier numerically controlled oscillator.

8. The apparatus of claim 7, wherein the carrier numerically controlled oscillator provides a reference signal to the tuner.

9. The apparatus of claim 7, further comprising a decimation circuit for processing an output of the tuner.

10. The apparatus of claim 9, wherein the code numerically controlled oscillator controls a sampling rate of the decimation circuit.

11. An integrated mobile device comprising:

an oscillator operable to produce a cellular oscillator signal;

at least one numerically controlled oscillator, wherein the at least one numerically controlled oscillator is operable to generate, in response to the cellular oscillator signal and the frequency control value, a signal that is used for processing GPS satellite signals; and

a processor operable to;

produce a frequency error signal to control the oscillator so as to cause the integrated mobile device to operate within cell phone network specifications;

produce a frequency control value;

search for a pilot tone or a carrier signal by tuning a frequency of the oscillator,

fix the frequency of the oscillator when the pilot tone or the carrier signal are not found;

search for the GPS satellite signals; and

return to searching for the pilot tone or the carrier signal when the GPS satellite signals are not found.

12. The integrated mobile device of claim 11, wherein the oscillator is a voltage controlled oscillator.

13. The integrated mobile device of claim 11, further comprising assisted GPS circuitry.

14. The integrated mobile device of claim 11, wherein the frequency control value is a digital word.

15. The integrated mobile device of claim 11, further comprising a memory for storing frequency control software for adjusting the frequency of the voltage controlled oscillator.

16. The integrated mobile device of claim 11, further comprising, at least one processing channel coupled to an analog-to-digital converter, wherein the at least one processing channel is adjusted by a tuner under a control of the at least one numerically controlled oscillator.

17. The integrated mobile device of claim 16, wherein the at least one numerically controlled oscillator comprises a carrier numerically controlled oscillator that provides a reference signal to the tuner.

18. The integrated mobile device of claim 17,. further comprising a decimation circuit for processing an output of the tuner.

19. The integrated mobile device of claim 18, wherein the at least one numerically controlled oscillator comprises a code numerically controlled oscillator that controls a sampling rate of the decimation circuit.

20. A mobile device comprising:

means for producing-a cellular oscillator signal;

means for producing a frequency error signal for controlling the oscillator to operate the mobile device within cell phone network specifications and producing a frequency control value;

means for generating, in response to the cellular oscillator signal and the frequency control value, a signal that is used for processing GPS satellite signals; and

means for searching for a pilot tone or a carrier signal by tuning a frequency of the means for producing the cellular oscillator signal;

means for fixing the frequency of the means for producing the cellular oscillator signal when the pilot tone or the carrier signal are not found;

means for searching for the GPS satellite signals; and

means for returning to searching for the pilot tone or the carrier signal when the GPS satellite signals are not found.