  Digital phase-locked loops (DPLLs) are nonlinear feedback-controlled systems
that are widely used in electronic communication and signal processing
applications. In most of the applications they work in coupled mode, however,
vast of the studies on DPLLs concentrate on the dynamics of a single isolated
unit. In this paper we consider both one- and two-dimensional networks of DPLLs
connected through a practically realistic nonlocal coupling and explore their
collective dynamics. For the one-dimensional network we analytically derive the
parametric zone of stable phase-locked state in which DPLLs essentially work in
their normal mode of operation. We demonstrate that apart from the stable
phase-locked state, a variety of spatiotemporal structures including chimeras
arise in a broad parameter zone. For the two-dimensional network under nonlocal
coupling we identify several variants of chimera patterns, such as strip and
spot chimeras. We identify and characterize the chimera patterns through
suitable measures like local curvature and correlation function. Our study
reveals the existence of chimeras in a widely used engineering system,
therefore, we believe that these chimera patterns can be observed in
experiments as well.
