Algorithms are developed for use in improving robust estimators of the vari
ance and auto- and crosscorrelation functions and the coefficients of Fouri
er series applied as descriptive features. By means of these: features, the
degree of diagnostic validation may be increased beyond that which may be
achieved with the well-known algorithms To predict malfunctions, algorithms
for the analysis of noise that are carriers of information about hidden al
terations that precede major faults are proposed. One possible alternative
implementation of the proposed algorithms in diagnostic information systems
is presented.