On the Peculiarities of The Behaviour Of The Instantaneous Frequency of APSK-N-Signal At The Linear Selective System Output In The Presence Of ISI

The paper studies the behavior of the instantaneous frequency of a multi-position amplitude-phase-manipulated signal at the output of linear selective systems under conditions of strong intersymbol interference. On the basis of the used model, an analytical expression is obtained, which makes it possible to estimate the frequency changing of this type of signal at the output of linear selective systems. The result of the analysis of the obtained expression by means of mathematical simulating identified common properties that, in particular, can be used to create highly efficient symbolic synchronization systems, which can be used both in data transmission systems operating under strong intersymbol interference.