Phase error dynamics of a class of DPLLs in presence of cochannel interference

Nonlinear dynamics of a class of conventional digital phase-locked loops (DPLLs) and its modified structure using loop digital filter modification has been studied analytically as well as through computer simulation. The presence of an interference signal considerably disturbs the dynamical stability of the conventional DPLL but the modified structure is capable of withstanding this disturbance to a larger extent. A qualitative explanation of the observation has been given using bifurcation theory.