This work describes the propagation properties of the so-called
symmetric interior penalty discontinuous Galerkin (SIPG) approximations
of the 1-d wave equation. This is done by means of linear approximations
on uniform meshes. First, a careful Fourier analysis is constructed,
highlighting the coexistence of two Fourier spectral branches or
spectral diagrams (physical and spurious) related to the two components
of the numerical solution (averages and jumps). Efficient filtering
mechanisms are also developed by means of techniques previously proved
to be appropriate for classical schemes like finite differences or
P1-classical finite elements. In particular, the work presents a proof
that the uniform observability property is recovered uniformly by
considering initial data with null jumps and averages given by a bi-grid
filtering algorithm. Finally, the book explains how these results can be
extended to other more sophisticated conforming and non-conforming
finite element methods, in particular to quadratic finite elements,
local discontinuous Galerkin methods and a version of the SIPG method
adding penalization on the normal derivatives of the numerical solution
at the grid points. This work is the first publication to contain a
rigorous analysis of the discontinuous Galerkin methods for wave control
problems. It will be of interest to a range of researchers specializing
in wave approximations.