modest diameter telescope), and VHIRES spectrograph at power resolution R = 45000.

The plot shows all spectra acquired (VisualSpec for the visu) during increasing light phase.
Times resolution (= exposure time) is of 5 minutes.
This one shot show spectral resolution (thin red lines are front
the Thor/Ar lamps):

Ok, the signal to noise ratio value is only 10, but the shock wave events are clearly visible.
Unexpected because the very high spectral resolution of the setup and V=7.7 mean magnitude of RR Lyrae.
More about VHIRES: http://www.astrosurf.com/buil/vhires/test.htm
Large potential, more than expected.
Christian