Blazhko stars: always distorted?
  Reexamination of the amplitude ratios of the photometric and radial velocity changes of Blazhko RRab stars in their different Blazhko phases shows that a normal amplitude ratio occurs near the phase of maximum amplitude. Checking the Fourier parameters of maximum amplitude light curves with different methods proved, however, that none of these light curves can be regarded as a normal RR Lyrae type light curve. 
J. Jurcsik, J.M. Benko and B. Szeidl