  We use the grid of hydrodynamic accretion disc calculations of Stehle (1999)
to construct orbital phase dependent emission line profiles of thin discs
carrying spiral density waves. The observational signatures of spiral waves are
explored to establish the feasibility of detecting spiral waves in cataclysmic
variable discs using prominent emission lines in the visible range of the
spectrum. For high Mach number accretion discs (M = 15-30), we find that the
spiral shock arms are so tightly wound that they leave few obvious fingerprints
in the emission lines. Only a minor variation of the double peak separation in
the line profile at a level of 8% is produced. For accretion discs in outburst
(M = 5-20) however, the lines are dominated by the emission from an m=2 spiral
pattern in the disc. We show that reliable Doppler tomograms of spiral shock
patterns can be reconstructed provided that a signal to noise of at least 15, a
wavelength resolution of 80 km/s and a time resolution of 50 spectra per binary
orbit is achieved. We confirm that the observed spiral pattern in the disc of
IP Pegasi can be reproduced by tidal density waves in the accretion disc and
demands the presence of a large, hot disc, at least in the early outburst
stages.
