The present invention relates to a multiple carrier smoothing method for navigation satellite signals, in particular a three carrier smoothing method for Galileo signals. It provides a smoothed code solution, which is ionosphere-free to the first order and whose noise is reduced to sub-decimeter level. The method involves integer ambiguities, which can be resolved reliably. The sensitivity of the new method to receiver biases and ionospheric delays of the second order is small. The performance of the three carrier smoothing method allows to reduce the averaging interval to ⅕-th of its current standard value. The results refer to pseudo ranges and are geometry independent.