Method and apparatus for adapting a receiver frequency plan according to location

• US 20070247357A1
• Filed: 04/24/2006
• Published: 10/25/2007
• Est. Priority Date: 04/24/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: U Nav Microelectronics Corp (Qualcomm, Inc.)
• Inventors: Lin, Qiang
• Granted Patent: US 7,683,829 B2
• Time in Patent Office: Days
• US Class Current: 342/357.420
• CPC Class Codes: G01S 19/21 Interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service
• CPC Class Codes: G01S 19/36 relating to the receiver frond end

Abstract

A selectable frequency source for use in GPS receivers. A device in accordance with the present invention comprises a reference frequency source, a first divider, coupled to the reference frequency source, the first divider having a first dividing factor, a first mixer, coupled to the first divider, a filter, coupled to the first mixer, a voltage controlled oscillator, coupled to the filter, a second divider, coupled between the voltage controlled oscillator and the first mixer, the second divider having a second dividing factor, and a second mixer, coupled to an output of the voltage controlled oscillator, for mixing a GPS signal with the output of the voltage controlled oscillator, wherein at least one of the first dividing factor and the second dividing factor is changed to change a frequency output of the voltage controlled oscillator.

Claims

1. A selectable frequency source for use in a Global Positioning System (GPS) receiver, comprising:

a reference frequency source;

a first divider, coupled to the reference frequency source, the first divider having a first dividing factor;

a first mixer, coupled to the first divider;

a filter, coupled to the first mixer;

a voltage controlled oscillator, coupled to the filter;

a second divider, coupled between the voltage controlled oscillator and the first mixer, the second divider having a second dividing factor; and

a second mixer, coupled to an output of the voltage controlled oscillator, for mixing a GPS signal with the output of the voltage controlled oscillator, wherein at least one of the first dividing factor and the second dividing factor is changed to change a frequency output of the voltage controlled oscillator.

2. The selectable frequency source of claim 1, wherein the frequency output of the voltage controlled oscillator is changed by changing the second dividing factor.

3. The selectable frequency source of claim 2, wherein the frequency output of the voltage controlled oscillator is changed when the GPS receiver determines that the GPS receiver is in a predetermined geographic region.

4. The selectable frequency source of claim 3, wherein the predetermined geographic region is determined by a presence of an interfering signal.

5. The selectable frequency source of claim 4, wherein the interfering signal is a PDC signal.

6. The selectable frequency source of claim 3, wherein the predetermined geographic region is determined by the GPS receiver determining a geoposition.

7. The selectable frequency source of claim 3, wherein the predetermined geographic region is determined by determining the location of an Internet Protocol (IP) address.

8. A selectable frequency source for use in a Global Positioning System (GPS) receiver, comprising:

a reference frequency source generating a reference frequency;

a circuit, coupled to the reference frequency source, the circuit having an output frequency which is scaled in relation to the reference frequency;

a mixer, coupled to the circuit, for mixing a GPS signal with the output frequency of the circuit, wherein the output frequency of the circuit is changed to change a frequency output of the mixer.

9. The selectable frequency source of claim 8, wherein the output frequency is changed by changing a multiplication factor of the circuit.

10. The selectable frequency source of claim 8, wherein the output frequency is changed by changing a division factor of the circuit.

11. The selectable frequency source of claim 8, wherein the output frequency is changed when the GPS receiver determines that the GPS receiver is in a predetermined geographic region.

12. The selectable frequency source of claim 11, wherein the predetermined geographic region is determined by a presence of an interfering signal.

13. The selectable frequency source of claim 12, wherein the interfering signal is a PDC signal.

14. The selectable frequency source of claim 11, wherein the predetermined geographic region is determined by the GPS receiver determining a geoposition.

15. The selectable frequency source of claim 11, wherein the predetermined geographic region is determined by determining the location of an Internet Protocol (IP) address.

16. The selectable frequency source of claim 8, wherein the circuit comprises a first divider, and a second divider, and a ratio between the first divider and the second divider determines the output frequency of the circuit.

17. The selectable frequency source of claim 16, wherein the circuit further comprises a third divider, and a scaling factor of the third divider determines the output frequency of the circuit.

18. A method for changing a local oscillator frequency in a Global Positioning System (GPS) receiver, comprising:

determining that the GPS receiver is in a predetermined geographic region; and

changing the local oscillator frequency when the GPS receiver is in the predetermined geographic region.

19. The method of claim 18, wherein the predetermined geographic region is determined by a presence of an interfering signal.

20. The method of claim 18, wherein the predetermined geographic region is determined by the GPS receiver determining a geoposition.