Allan deviations σa of estimated ambient noise (blue triangles) and the measured gravitational acceleration from post-corrected data (orange diamonds) as a function of integration time τ. Displayed error bars mark 1 σ confidence intervals. Post correction improves the instability at 1 s by a factor of 8 and, here, reduces the measurement time necessary to achieve a target instability by a factor 64. The dashed lines reflect the gain by averaging. We estimate the ambient noise from the phase correction data obtained in our post correction (see “Methods” section).