Long term monitoring of intermediate polars is performed as a part of the InterLongitude Astronomy campaign. High quality and long time series observations allow us to investigate fine effects on complex light curves. In
the case of MU Cam we have investigated the periodic modulation of the spin phases with the orbital phase. This dependency was already described by Kim et al. (2005). As an explanation they proposed inhomogeneous accretion flow from the secondary. However based on our new data we can propose simple explanation as the influence of orbital sidebands in the periodic signal produced by intermediate polar. This explanation is supported by the fact that the changes in spin maxima phase are observed mainly when the sideband frequency is dominant in the periodogram. This result was presented on conferences in Bezovec and Telč.
