Radio devices and complexes of strategic application are highly complicated technical systems working under difficult conditions including the conditions of intentional interference. Radio systems have been developed at various times and with various technical parameters and operation requirements, which makes their common use even more difficult due to their mutual influence. The article examines semi-Markov model of maintaining electromagnetic stability of system control for radio complexes. We suggest analytical tools for solving the problem of maintaining electromagnetic compatibility of the total of radio complexes on the basis of the analysis of the state of the model in conditions of interference, the use of state-space representation and the relativity theory. Thus, the suggested tools allow to calculate the efficiency of radio systems operation, probability of task performance for the period not exceeding the predetermined one. The work offers the methods of studying the dependence of this efficiency parameter on the following parameters of system functioning: the expected value of the time of radio system operation during task performance, the expected value of the start of interference, the expected value of restoring RS operation capacity, the probability of the fulfillment of conditions of overlapping frequencies and the interference power exceeding the limit value of the signal power. The resulting mathematical tools allow to calculate the average time of effective radio system functioning in conditions of unintentional and intentional interference, calculate the probability of effective simultaneous work of two radio systems with their unintentional mutual interference. They will also help us determine the optimum plan of frequency resource for interference reduction. We have developed the methods for determining the optimum working plan for a number of heterogeneous radio complexes, thus aiming to build a single effective system of their control by changing dynamically the parameters of their radio emissions.