Calculation of location in a satellite navigation system with extended convergence zone

摘要

An apparatus for calculating the location of a receiver 201 in a satellite navigation system, the apparatus being arranged to calculate a location of the receiver by means of an algorithm that utilises an estimate of receiver location and/or an estimate of absolute time, the apparatus being arranged to perform the calculation in such a way as to extend a convergence zone within which the algorithm is capable of generating the correct location for the receiver despite an error in the estimate(s). The size of the convergence zone is dependent on which satellites are selected to calculate location.