The invention concerns a real-time navigation method for locating a rover using three-carrier radio signals of three different frequencies to determine the position of a user, transmitted by satellites. The method comprises a first step for determining ''extra-wide lane'' carrier phase ambiguity, a second step for estimating ''wide-lane'' phase ambiguity, and a third step for resolving the phase ambiguity of one of the frequencies. An additional step consists in the application of real-time ionospheric corrections during the third step, these ionospheric corrections being based on a continuously updated ionospheric model of said ionospheric layer calculated by a fixed ground reference station combined with geodetic data calculated by a so-called master fixed ground reference station. The invention also concerns a system for implementing the method.