Pseudo-power spectra reconstructed from the half-differences between maps from the first and the second half of each ring (continuous lines) and the half-differences between maps restricted to Survey 1 and 2 (dashed lines) for, respectively, the dipole calibrated channels (right) and the sub-millimetre ones (right). These pseudo-spectra were computed using Galactic masks, removing 15% (≤353 GHz) or 40% of the sky (sub-mm channels), combined with the Planck point source mask. For high-frequency channels, power spectra are dominated by signal and destriping residuals, due to gradients inside the pixels, which are not scanned at exactly the same positions in the two data sets. In the survey differences, other systematics like time response, pointing drifts, and residual gain variations also induce larger residuals.