Measurement error covariance in GNSS receiver circuitry, pseudoranges, reference position

摘要

A Global Navigation Satellite System (GNSS) receiver determines a measurement error covariance from a reference position and a set of measured pseudoranges from a set of GNSS satellites. The position and velocity solution is determined from the measurement error covariance and the set of measured pseudoranges. The measurement error covariance is determined as function of the difference between a reference pseudorange and measured pseudorange. The reference pseudorange is computed from the reference position to a satellite. The measurement error covariance is determined as function of the difference only if the measured pseudorange is greater than the reference pseudorange. The GNSS receiver also determines measurement error covariance as function of one or more of correlation peak shape, difference, the correlation peak shape, a received signal to noise ratio and a tracking loop error.

主权项

1. A method of operating a navigation assistant that includes a Global Navigation Satellite System receiver, comprising:
determining in circuitry in a the Global Navigation Satellite System receiver a first pseudorange from a first Global Navigation Satellite System satellite; determining in the Global Navigation Satellite System receiver circuitry a reference range from a reference position to the first GNSS satellite; determining in the Global Navigation Satellite System receiver circuitry a measurement error as a function of the difference between the reference range and the first pseudorange; weighing in the Global Navigation Satellite System receiver circuitry the first pseudorange by the measurement error; computing a position solution from a set of pseudoranges that include the weighed first pseudorange, the position solution includes at least one of a position, velocity, and error covariance and the reference position is an a priori position estimate of a Kalman filter determined from a prior position; determining in the Global Navigation Satellite System receiver circuitry a measurement error covariance as function of the difference only if the measured pseudorange is greater than the reference pseudorange; computing the measurement error covariance in the Global Navigation Satellite System receiver circuitry at least partially according to:R=∑N⁢(Δ⁢⁢ρ)⁢(Δ⁢⁢ρ)TN-HCHTin which R represents the error covariance, Δρrepresents a residual pseudorange error of the first set of satellites, H represents an n×4 matrix comprising unit vectors pointing from an approximate user position to the n visible satellites, C represents an estimate of error covariance from term E[(ΔX)(ΔX)T], N is an integer representing an observation window, the operator T represents a transpose operation and the operator, Σ represents a summation operation;
determining in the Global Navigation Satellite System receiver circuitry a second measurement error as function of a correlation peak shape; modifying, in the Global Navigation Satellite System receiver circuitry, the measurement error based on the second measurement error; and providing the measurement error based on the second measurement error to the navigation assistant.