This paper presents a technique that allows a systematic way to define masks that limit the statistical behavior of the single-entry interference impacting a satellite link in order to ensure an adequate link performance. The proposed technique considers the joint effect of degradation due to rain and external interferences. In the method, a series expansion in a basis of orthonormal functions is used to represent the probability density function of the single-entry interference - thermal noise ratio and the limiting mask is obtained by solving a conveniently defined constrained optimization problem. In order to illustrate the robustness of this technique, an example of application is also presented.