1. A method of operating a system comprising at least one processor and memory with instructions for estimating integer ambiguities from carrier phase observations of GNSS signals received at multiple stations from at least four satellites, comprising: a. determining from the carrier phase observations a ranked plurality of candidate sets of estimated integer ambiguities, b. applying a criterion to select a first candidate set of the ranked plurality of candidate sets as a selected candidate set, c. forming a matrix G such that the image formed when matrix G is linearly combined with the selected candidate set is equal to the image formed when matrix G is linearly combined with a second candidate set, and d. applying the matrix G to the selected candidate set to determine a modified candidate set of estimated integer ambiguities.