Patent ID: 8842042
Filing Date: 2014-09-23
Classification: G01S

Abstract:
1. A non-transitory tangible computer readable storage medium storing a computer program for correcting satellite ephemeris error, the computer program comprising executable instructions that cause a computer to: a) determine at least one of measured time difference and measured frequency difference associated with signal replicas received via at least two different satellites from a plurality of calibration transmitting means of known but different geographical locations; b) calculate at least one of expected time difference and expected frequency difference by propagating initial satellite ephemeris elements including position and velocity vectors of the at least two different satellites to corresponding times of the at least one of expected time difference and expected frequency difference; and c) determine changes to the satellite ephemeris elements for correcting satellite ephemeris error by calculating a first difference between said at least one of expected time difference and expected frequency difference with the at least one of measured time difference and measured frequency difference, wherein the executable instructions to determine changes to the satellite ephemeris elements for correcting satellite ephemeris error comprises executable instructions that cause the computer to calculate an ephemeris correction vector as a product of the first difference and the changes to the satellite ephemeris elements, wherein the ephemeris correction vector [A] is calculated as wherein TDOA is the measured time difference, FDOA is the measured frequency difference, <TDOA> is the expected time difference, and <FDOA> is the expected frequency difference—and the a