  Observers are well known in control theory. Originally designed to estimate
the hidden states of dynamical systems given some measurements, the observers
scope has been recently extended to the estimation of some unknowns, for
systems governed by partial differential equations. In this paper, observers
are used to solve inverse source problem for a one-dimensional wave equation.
An adaptive observer is designed to estimate the state and source components
for a fully discretized system. The effectiveness of the method is emphasized
in noise-free and noisy cases and an insight on the impact of measurements'
size and location is provided.
