The basis of the vibroseismic researches data is either harmonic, or frequency modulated signals recorded in discrete time. The problem of selection of such signal from the noisy vibroseismic data under condition of preservation of a wave shape, arises in a number of practical cases. One of ways of a solution of standing here problems is the use of nonlinear, in particular, median filters, which allow to preserve derivative discontinuities of a treated signal. However on periodic signals the behavior of standard median filters is similarly to behavior linear ones (with increase of length of the filter grows its smoothing effect). This circumstance essentially restricts the possibility of the median filter and their effectiveness.

In this paper, we consider a generality of median filters – weighted cophase median filters. For such a filter the above restriction either absent (in a case of harmonic signal) or considerable relaxed (in a case of frequency modulated signal). We offer an structure of parallel filtering of a signal and some decision rules for restoring the wave shape in designed frequency band. Investigations on models expose that in a case of pure signal the correlation coefficient on the filter input/output is closely to unit, and in a case of noisy signal the correlation coefficient of sounding signal/output is considerable increased.