Utilizing Robust Estimation in GPS Networks The baseline observations obtained from the processing of GPS carrier phase measurements and described as the differences of coordinate components between points have been adjusted using the method least squares LS . Nevertheless LS is sensitive to outliers. Therefore, robust methods must be used to detect outliers in GPS networks. L1 norm minimization is a robust method to detect outliers in geodetic networks. Adjustment of geodetic networks by this method can be realized solving a linear programming problem. In this study, the adjustment of a GPS network by the L1 norm minimization method has been studied with the consideration of the correlations among baseline components. The efficiency and robustness of the method have been demonstrated with a numerical example. Moreover, internal reliability measures have been computed by taking into account the correlations among observations