Instruments and Systems: Monitoring, Control, and Diagnostics Annotation << Back Estimation of spectrum and trends in processes, signals and functions Dmitriev E.V. The article deals with the analytical method estimating spectrum and nonlinear trend of the discrete process. The method is based on spectrum interpretation as a sum of power polynomial and a package of sinusoidal terms. It uses the functions’ properties and implements the least-squares method to determine the process parameters. Контактный телефон (4732) 47-85-84. E-mail: kvsj3903@yandex.ru.