Patent ID: 8203482
Filing Date: 2012-06-19
Classification: G01S

Abstract:
1. A GNSS-based positioning device comprising a receiver that computes a horizontal protection level (HPL) or a vertical protection level (VPL), that bound, up to a given confidence level 1−α, the horizontal and vertical components, respectively, of the position estimation error δ of a least squares-based GNSS navigation solution with a number m of estimated parameters, which navigation solution is based on n observations and an n×m observation matrix H and which navigation solution also provides a residuals vector r, and sets off or displays an alarm if said HPL or VPL exceeds an application-defined horizontal or vertical error tolerance threshold; and wherein the receiver computes the horizontal protection level HPL or the vertical protection level VPL according to one of the following expressions: where: ∥r∥ is the Euclidean norm of the least squares estimation residuals vector r; and a h and where k is an isotropic confidence ratio computed by numerically solving the following expression Eq. 3 which links k with n, m and α: where: Γ is Euler's Gamma function; and,