The substantiation of mathematical model of an additive mix useful and casual signals for the analogue wire channel of the alarm system of system of protection of military objects is stated. The useful signal is represented as the determined function with unknown information parametre. Casual signal is presented as current realisation of casual process which is presented on the limited interval of supervision in the form of final Fourier’s number. The information parametre of a useful signal which defines a condition of security system, is as the decision of system of the linear algebraic equations.
mathematical model, a signal, the casual signal, , an additive mix, Fourier’s number