  We calculate the X-ray diffraction spectrum produced by a pinned charge
density wave (CDW). The signature of the presence of a CDW consists of two
satellite peaks, asymmetric as a consequence of disorder. The shape and the
intensity of these peaks are determined in the case of a collective weak
pinning using the variational method. We predict divergent asymmetric peaks,
revealing the presence of a Bragg glass phase. We deal also with the long range
Coulomb interactions, concluding that both peak divergence and anisotropy are
enhanced. Finally we discuss how to detect experimentally the Bragg glass phase
in the view of the role played by the finite resolution of measurements.
