V.I. Vladimirov, A.V. Petrov, V.M. Shatskikh

The important stage in the development of techniques for evaluating the effectiveness of data link jamming is a change-over from deterministic evaluation techniques to probability (statistic) ones which enable us to account for the admissible risk (the probability of failure for data link jamming ). Thus to construct data link jamming characteristics it is essential to use probability models which adequately reflect the effect of stochastic nature of the influence of environment on wave propagation upon the character of change of the resulting jamming to signal ratio(J/S ratio) at the receiver input. A data link jamming characteristic is considered to mean the dependence of probability of data link jamming on the J/S ratio with a numerical value of the suppression ratio taken as a parameter, as applied to electromagnetic environment at the receiver input of the data link as the objective of jamming. The probability of jamming is the probability such that given the average J/S power ratio their instantaneous power ratio will be more than the value of the radio interference suppression factor. One of the most-used probability density functions to allow for probabilistic properties of signal (jam) power in radio wave multipath conditions is gamma-distribution. Knowing the probability density function for signal and jamming levels one can calculate the probability density function for J/S ratio at the receiver input that is the objective of jamming by using the method of functional transformation of random variables and hence to construct jamming characteristics. It was demonstrated that to provide reasonably high jamming probabilities it is necessary to increase J/S ratio at the receiver input compared to the value of the suppression ratio by a value that depends on the parameters of the form of signal and jamming power distribution at the receiver input of the data link being jammed. The dependencies also allow one to solve the problem of calculating average J/S ratio at the receiver input which provides data link jamming with the desired probability.