Goodness of the reconstruction of the CMB B-mode signal (lensing+r = 0.01) after needlet filtering (top) in the SWIPE (red) and SO (blue) patches or after smoothing CMB maps with input angular resolution of FWHM = 9′ to bring them to FWHM = 91′ in the SO footprint (bottom). On the left: Mean angular power spectra (over 200 CMB-only simulations) of the input exact B maps reconstructed with a full-sky EB-decomposition of Q and U (solid lines); those of the reconstructed maps after needlet filtering or beam convolution (dots and diamonds); and the corresponding residuals (dashed lines). The plot on the right represents the effective tensor-to-scalar ratios associated with the absolute differences between output power spectra after needlet filtering and beam convolution and exact input ones in the SWIPE (red) and SO (blue) patches. A binning scheme of Δℓ = 3 for ℓ ≤ 4, Δℓ = 6 for 5 ≤ ℓ ≤ 28, and Δℓ = 15 for ℓ ≥ 29 is employed for the spectra computed in the LSPE-SWIPE patch, while a constant Δℓ = 15 for those estimated in the SO footprint. The error-bars highlight the uncertainty on the mean of the simulations at 1σ.