Patent ID: 9557419
Date: 2017-01-31
CPC Classifications: G01S

Claim:
1. Method, carried out by a computer or set of computers, for generating accuracy information for an ionosphere model calculated using a parameter estimation procedure based on phase observations made using a plurality of ground stations, wherein each phase observation is obtained from at least two signals transmitted from a satellite to a ground station, each of the at least two signals having a different frequency, and the accuracy information is usable in a GNSS positioning system for estimating a position of a rover, the method comprising the steps of: for each of at least some of the phase observations having fixed or converged ambiguities, obtaining phase residual information of the parameter estimation procedure; and computing coordinates of a pierce point on a sphere around the earth, the sphere being defined by an ionosphere single layer model, wherein the coordinates indicate where the at least two signals from which the phase observation has been obtained pierce the sphere; mapping, for each pierce point, the phase residual information of the corresponding phase observation to the vertical at the pierce point to generate vertical residual information; for each of at least some of the points of an equidistant grid on the sphere, each point being hereinafter referred to as “grid point”, identifying pierce points within a threshold distance from the grid point on the sphere; selecting grid points for which the number of identified pierce points exceeds a threshold number; computing, for each selected grid point, generating the accuracy information for the ionosphere model based on