System and method for determining a magnetic field using a mobile device

1. A method of determining a magnetic field using a mobile device, the method comprising:

determining location information of the mobile device;

obtaining magnetic field data from a model of Earth's magnetic field based on the location information and without sensing a magnetic field at the device, the magnetic field data representing Earth's magnetic field at the location of the mobile device;

determining, contemporaneous with the determining of the location information, orientation information of the mobile device at the location;

applying the orientation information to the obtained magnetic field data representing the Earth's magnetic field to compute a simulated Earth's magnetic field in the orientation of the mobile device, the simulated Earth's magnetic field being separate from any magnetic field data output from a magnetometer at the mobile device; and

outputting the simulated Earth's magnetic field.

2. The method of claim 1 , wherein the orientation information comprises angular position information of the mobile device.

3. The method of claim 1 , wherein applying the orientation information comprises rotating the magnetic field data using a rotation matrix.

4. The method of claim 1 , wherein the model of Earth's magnetic field comprises a predetermined set of magnetic field data arranged according to location.

5. The method of claim 4 , wherein the predetermined set of magnetic field data is located remote from the mobile device.

6. The method of claim 1 , wherein the model of Earth's magnetic field comprises a predetermined set of computations using the location information.

7. The method of claim 1 , further comprising adjusting the magnitude of the simulated Earth's magnetic field based on a magnetometer reading.

8. The method of claim 1 , further comprising using the simulated Earth's magnetic field as input to an application that was developed to use one or more magnetometer readings as input.

9. The method of claim 1 , further comprising removing at least a portion of the magnetic field from a magnetometer reading to detect magnetic interference.

10. A computer readable storage medium for determining a magnetic field using a mobile device, the computer readable storage medium comprising computer executable instructions which, responsive to being executed by a processor, cause the processor perform operations comprising:

determining location information of the mobile device;

obtaining magnetic field data from a model of Earth's magnetic field based on the location information and without sensing a magnetic field at the device, the magnetic field data representing Earth's magnetic field at the location of the mobile device;

determining, contemporaneous with the determining of the location information, orientation information of the mobile device at the location;

applying the orientation information to the obtained magnetic field data representing the Earth's magnetic field to compute a simulated Earth's magnetic field in the orientation of the mobile device, the simulated Earth's magnetic field being separate from any magnetic field data output from a magnetometer at the mobile device; and

outputting the simulated Earth's magnetic field.

11. The computer readable storage medium of claim 10 , wherein the orientation information comprises angular position information of the mobile device.

12. The computer readable storage medium of claim 10 , wherein applying the orientation information comprises rotating the magnetic field data representing the Earth's magnetic field using a rotation matrix.

13. The computer readable storage medium of claim 10 further comprising computer executable instructions for using the simulated Earth's magnetic field as input to an application that was developed to use one or more magnetometer readings as input.

14. The computer readable storage medium of claim 10 further comprising computer executable instructions for removing at least a portion of the magnetic field from a magnetometer reading to detect magnetic interference.

15. A mobile device comprising a processor coupled to a memory, a magnetometer and an accelerometer, the memory comprising computer executable instructions for:

determining location information of the mobile device;

obtaining magnetic field data from a model of Earth's magnetic field based on the location information and without sensing a magnetic field at the device, the magnetic field data representing Earth's magnetic field at the location of the mobile device;

determining, contemporaneous with the determining of the location information, orientation information of the mobile device at the location;

applying the orientation information to the obtained magnetic field data representing the Earth's magnetic field to compute a simulated Earth's magnetic field in the orientation of the mobile device, the simulated Earth's magnetic field being separate from any magnetic field data output from a magnetometer at the mobile device; and

outputting the simulated Earth's magnetic field.

16. The mobile device of claim 15 further comprising a gyroscope for determining angular movement of the mobile device.

17. The mobile device of claim 15 , wherein the orientation information comprises angular position information of the mobile device.

18. The mobile device of claim 15 , wherein applying the orientation information comprises rotating the magnetic field data using a rotation matrix.

19. The mobile device of claim 15 , wherein the memory further comprises computer executable instructions for using the magnetic field as input to an application that was developed to use one or more magnetometer readings as input.

20. The mobile device of claim 15 , wherein the memory further comprises computer executable instructions for removing at least a portion of the magnetic field from a magnetometer reading to detect magnetic interference.