1. A method 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 one 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 a 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.