1. Method to estimate parameters derived from global navigational satellite system (GNSS) signals useful to determine a position, comprising obtaining observations of a GNSS signal from each of a plurality of GNSS satellites; feeding the observations to a filter having a state vector at least comprising a float ambiguity for each received frequency of the GNSS signals, each float ambiguity constituting a real number estimate associated with an integer number of wavelengths of the GNSS signal between a receiver of the GNSS signal and the GNSS satellite from which it is received, and the filter being for estimating a float value for each float ambiguity of the state vector; selecting a subset of the ambiguities of the state vector; assigning integer values to the estimated float values of the float ambiguities of the subset to define a plurality of candidate sets; determining a quality measure for each of the candidate sets; and forming a weighted average of the candidate sets.