Dual LO receiver

• US 8,044,856 B1
• Filed: 01/21/2009
• Issued: 10/25/2011
• Est. Priority Date: 01/21/2009
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm Atheros Incorporated (Qualcomm, Inc.)
• Inventors: Lin, Qiang
• Primary Examiner(s): Tarcza; Thomas H.
• Assistant Examiner(s): LIU, HARRY K
• Application Number:
  US12/356,757
• Time in Patent Office: 1,007 Days
• Field of Search: 342/357.06, 342/357.75
• US Class Current: 342/357.75
• CPC Class Codes: G01S 19/35 Constructional details or hardware or software details of the signal processing chain
• CPC Class Codes: H03J 2200/11 Cellular receiver, e.g. GSM, combined with a GPS receiver

Abstract

A selectable frequency source for use in GPS receivers. A device in accordance with one or more embodiments of the present invention comprises at least one reference frequency source, a circuit, coupled to the at least one reference frequency source, and a mixer, coupled to an output of the circuit, for mixing a GPS signal with the output of the circuit, wherein a frequency output of the mixer is changed based on an input to the circuit.

Claims

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

at least one reference frequency source;

a circuit, coupled to the at least one reference frequency source; and

a mixer, coupled to an output of the circuit, for mixing a GPS signal with the output of the circuit,

wherein a frequency output of the mixer is changed based on an input to the circuit and wherein the input depends upon expected interference conditions.

2. The selectable frequency source of claim 1, wherein the circuit is coupled to a single reference frequency source.

3. The selectable frequency source of claim 2, wherein the frequency output of the circuit 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 frequency output of the circuit is manually changed.

7. 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 based on the reference frequency; and

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 based upon expected interference conditions to change a frequency output of the mixer.

8. The selectable frequency source of claim 7, wherein the output frequency is changed by changing an input signal to the circuit.

9. The selectable frequency source of claim 7, wherein the output frequency is changed when the GPS receiver determines that the GPS receiver is in a predetermined geographic region.

10. The selectable frequency source of claim 7, wherein the predetermined geographic region is determined by a presence of an interfering signal.

11. The selectable frequency source of claim 10, wherein the interfering signal is a PDC signal.

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

determining the presence of a signal outside of a GPS spectra; and

setting the local oscillator frequency to a predetermined frequency based on the presence of the signal outside of the GPS spectra.

13. The method of claim 12, wherein the signal outside of the GPS spectra is a PDC signal.

14. The method of claim 12, wherein the signal outside of the GPS spectra is a GSM signal.