Prof. A. Venedikov works on the time series analysis in the geophysical domain. The most important achievement is his method for the analysis of tidal data. The method allowed for the first time the processing of tidal series of arbitrary duration and gaps. The method has been extensively applied in many countries, e.g. in the International Centre for Earth Tides in Brussels. The most recent achievement of Prof. Venedikov is the development of a method for spectral analysis of arbitrary time series with unevenly spaced data.