Gnss positioning with fixing of carrier range ambiguities

Abstract

A method and apparatus are provided for calculating a position based on Global Navigation Satellite Systems (GNSS) signals. The method includes estimating a first state vector comprising a first set of float carrier range ambiguities using a first estimator, basedon first observations of the GNSS signals; and estimating a second state vector comprising a second set of float carrier range ambiguities using a second estimator, based on second observations of the GNSS signals. It further comprises fixing one or more first carrier range ambiguities, using a first strategy, based on the first set of float carrier range ambiguities; and fixing one or more second carrier range ambiguities, using a second strategy, based on the second set of float carrier range ambiguities. The first strategy for fixing the one or more first carrier range ambiguities is different from the second strategy for fixing the one or more second carrier range ambiguities. The method further includes: selecting a set of fixed carrier range ambiguities from among a plurality of different sets of fixed carrier range ambiguities, the plurality including at least the one or more fixed first carrier range ambiguities and the one or more fixed second carrier range ambiguities; and estimating the position based on the selected set of fixed carrier range ambiguities.