I assumed that the same noise is present in all 16 coils, but is incoherent, i.e. the scaling factor was sqrt(16)=4. Note that the 10Hz and harmonics are due to pick-up, and thus likely coherent at least in the ITMs. Thanks to the alternating magnet polarity, this coupling likely cancels to some degree for length noise, i.e. the attached plot is an over-estimate.