Radio light curve resulting from long-term monitoring of LS I +61 303 by the GBI at 8 GHz. The lower time axis is expressed in terms of MJD and the upper one in cycles of the long-term modulation, using P_long = 1667 d and T₀ = MJD 43366.275. These data have been averaged in time bins of width seven days. Two intervals are highlighted (green and yellow), which are analyzed individually, as explained in the text.