GLS periodograms of our indicators and window functions for Ross 318. The indicators are the pEW′ of chromospheric emission lines (He i D₃, NaI D, Hα, and Ca ii IRT in the visible-light channel of CARMENES, He i λ10833 Å and Paβ lines in the near-infrared channel), indices of photospheric absorption bands (TiO 7050, TiO 8430, VO 7436, VO 7942), and differential line width (dLW), chromatic index (CRX), radial velocity (RV), CCF FWHM, CCF contrast, and CCF bisector inverse slope (BIS) in each channel. Horizontal lines indicate the analytical 10% (dotted), 1% (dashed), and 0.1% (dash-dotted) false-alarm probability levels. N is the number of used data points after a 2σ clipping for each indicator. For most signals at a frequency f, there are aliases at 1 d⁻¹ − f. The red dotted line marks the rotation frequency f_rot = 0.0194d⁻¹ (P_rot = 51.5 d).