V.P. Ryzhov

In article it is shown, that in problems of a choice of a class and determination of parameters of signals at designing of information systems it is expedient to use the system approach. Thus the criterion of a choice should be multidimensional, switching on indicators of adequacy, functional stability and complexity of model of a signal. The procedure of a choice of the description of a signal on the basis of criterion of a minimum of average risk according to which from M bases for what the average risk is minimum is sampled is offered. Basis system-engineering approach in designing is the account of many aspects of performance and system operation (including interaction with other systems, with Wednesday) and use of poorly structured expert information. From results of calculation follows, that for the received models of subclasses of signals and distributions of their probabilities by the most preferable Haar's basis, then - Walsh's and Fourier are. Thus average risk for Haar's basis approximately 10 times less, than for basis Fourier.