In article it is indicated a possibility of increase in noise immunity of radar stations by means of methods of electronic countermeasures. It is shown that for assessment of their efficiency entropy indicators can be used. Features of their application are shown and also what at the solution of a number of the private tasks connected with assessment of quality of counteraction of electronic intelligence devices their use can be insufficient. Therefore the purpose of work consists in definition of the auxiliary information and power indicator characterizing the masking properties of radio signals during creation from them an additive system. 

The process of measuring the parameters of the signals to be explored by the electronic intelligence devices is analyzed. The analysis is made from a position of the second law of thermodynamics. It is shown that in case of revenues to a reception part of the equipment of electronic intelligence of an additive system of the radio signals (masking and masked) there will be a loss of in-formation. On the basis of it and with application of theories of information, probabilities and mathematical statistics the auxiliary indicators (Kullback–Leibler divergence and spectrum entropy) for determination of the masking properties of radio signals allowing to solve various problems of assessment of quality of radio interferences, including connected with definition of a possibility of counteraction of radio engineering investigation to stations are offered. The conditions of application of the offered criteria are defined in the analysis of alarm processes in frequency area.

Thus in work application of auxiliary information and power indicators by means of which it is possible to solve various problems of assessment of quality of radio interferences including connected with definition of a possibility of counteraction electronic intelligence devices due to additive signals processes is offered.