Patent ID: 6484098
Filing Date: 2002-11-19
Classification: G01S

Abstract:
A GPS method comprising:a measurement process of measuring each pseudo-range ri (i=1, 2, . . . , n) from respective one of received radio waves from n GPS satellites (n is a natural number equal to or greater than 3) captured by a GPS receiver mounted on a movable body; a detection process of detecting a generation of a multi-path of the respective one of the received radio waves; a first calculation process of approximately calculating a clock error t and coordinates (x, y, z) of the GPS receiver as a solution of n simultaneous equations by performing a convergence calculation with respect to n functions fi (x, y, z, t) having such variables as the clock error t and the coordinates (x, y, z), each of the n functions fi (x, y, z, t) representing the pseudo-range ri; a second calculation process of approximately calculating the clock error t and the coordinates (x, y, z) as a solution of n+1 simultaneous equations by performing a convergence calculation with respect to total n+1 functions obtained by adding one &agr; fn+1 (x, y, z, t) to the n functions fi (x, y, z, t), where the one &agr; fn+1 (x, y, z, t) is obtained by applying a weighting &agr; (&agr; is a real number which is equal to or greater than 1) to one function fn+1 (x, y, z, t) having such variables as the clock error t and the coordinates (x, y, z), the one function fn+1 (x, y, z, t) representing a pseudo-range rn+1 obtained when the center of the earth is regarded as one GPS satellite; an output process of outputting the coordinates (x, y, z) calculated in said first or second calculation process as current position data, which indicate a current position of the movable body; and a selection process of selecting said second calculation process when the generation of the multi-path is detected by said detection process.