| 摘要 |
A mobile station determines an approximate latitude using a measured feature of the Earth's magnetic field. An approximate longitude may also be determined. The mobile station uses the approximate latitude and longitude, if determined, to assist in determining a position fix for the mobile station, e.g., by determining a list of visible satellites in a satellite positioning system (SPS) during search and acquisition of satellite signals and/or using the approximate position as a seed position in the position computation. The feature of the Earth's magnetic field may be, e.g., inclination or vertical intensity, and may be determined using data from a three-dimensional magnetometer and a three-dimensional accelerometer. An instantaneous value of the magnetic field feature may be averaged to reduce the affects of motion and the presences of large metallic masses. |
