  The paper investigates recoverability of discrete time signals represented by
infinite sequences from incomplte observations. It is shown that there exist
wide classes of signals that are everywhere dense in the space of
square-summable signals and such that signals from these classes feature robust
linear recoverability of their finite traces under very mild restrictions on
the location of the observed data. In particular, the case arbitrarily sparse
and non-periodic subsequences of observations are not excluded.
