Method and apparatus for adapting a receiver frequency plan according to location
View Patent ↗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.
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 controlling the frequency of the voltage controlled oscillator, wherein at least one of the first dividing factor and the second dividing factor is automatically changed to change a frequency output of the voltage controlled oscillator, in response to an external interfering signal.
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 the presence of the 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, wherein the output frequency of the circuit is automatically changed to change a frequency output of the mixer in response to a presence of an external interfering signal.
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 legion is determined by the presence of the 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 fox 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
automatically changing the local oscillator frequency when the GPS receiver is in the predetermined geographic region in response to a presence of an external interfering signal.
19. The method of claim 18 , wherein the predetermined geographic legion is determined by a presence of the interfering signal.
20. The method of claim 18 , wherein the predetermined geographic region is determined by the GPS receiver determining a geoposition.