I. Introduction
Many physical processes found in real applications can be interpreted as a pulse process. Pulse signals, pulse sequences, or pulse trains are used as a model of the process in such applications as electronic warfare [1], radar [2], communications [3], geophysics [4], speech processing [5], medical and engineering diagnostics [6], [7], and others. Appropriate processing and analysis of pulse trains is the relevant problem for these applications. By analyzing pulse repetition interval, arrival time, or shape of pulses, one can get useful information about properties of a target, jamming signal, seismic source, minerals, voice, fault type of some equipment, a state of patient, etc. For example, changes in patient state are often indicated by well-known correlated changes of pulse shape in electro-cardiograms (ECGs) and electro-encephalograms (EEGs).