  We present the analysis of the multicolour CCD observations in the 2010
season of the Blazhko RRc star TV Boo. TV Boo shows a complex Blazhko
modulation dominated by two independent modulations with P_{fm1}=9.74 d and
P_{fm2}=21.43 d long periods. Both modulation components appear in the
frequency spectra as multiplet structures around the harmonics of the
pulsation. The positive value of the asymmetry parameter (Q=+0.51) of the
primary modulation suggests that it is similar in its character to the Blazhko
effect of most of the modulated RRab stars. Interestingly, the secondary,
lower-amplitude modulation exhibits a negative asymmetry parameter (Q=-0.22),
which is an unusually low value when compared to the Blazhko-modulated RRab
stars. Apart from the two modulation frequencies, the spectra also show an
additional frequency f' and its linear combinations with the pulsation and the
primary modulation f_{1}+f' and f_{1}-f'-f_{m1}. We conclude that the
additional frequency most probably belongs to a non-radial mode.
