Noise spectra of radiometers LFI18M, LFI22S, LFI25S, and LFI28S) estimated by the noise pipeline (black lines). All spectra are well-fit by Eq. (20) with a single knee frequency and slope (red lines). An excess near 1mHz is visible in LFI25S and LFI28S. This is approximately the bed-switching frequency of the sorption cooler, and the different slopes in LFI28S and LFI25S on the low-frequency side of the spectrum are possibly indications of thermal effects on the radiometer output.