We define the scale translation in discrete-time via the action of the group of automorphisms of the disk. Two important tools that we will use are the theory of automorphic functions and the theory of reproducing kernel Hilbert spaces. When the group is Fuchsian and of Widom type, we present a class of signals and systems which are both discrete-scale and discrete-time stationary. Finally a class of digital self-similar signals and systems is presented.