Maximum smearing with respect to sub-integration length for SKA-Low (left y-axis) and SKA-Mid (right y-axis) calculated using Eqs. (14) and (15), assuming the spin period and DM of PSR J0737–3039A, a mass of 1.4 M_⊙, and circular orbits. The blue, orange, and green lines denote orbital periods of 15 min, 1 h, and 2.45 h (PSR J0737–3039A), respectively, with the maximum acceleration labelled. The SDDS (dashed lines for SKA-Low and dotted lines for SKA-Mid) dominates over the TDDS (solid lines) when the sub-integration length is smaller than half of the dispersive delay time (∆t_DM = 76.1 s for SKA-Low and ∆t_DM = 1.2 s for SKA-Mid), and vice versa.