Russlk said:
I expect that the signal does not have a discrete frequency, so the better approach is to prevent the interference rather than try to filter it out. Shielding and common mode rejection should be all that is needed.
Yes, I believe such devices commonly use fixed low-pass filtering, the signals you are looking for are all very low in frequency so you can reject any above your highest frequency. But you want to start with the best possible signal you can - don't start with a rubbish signal and then try and improve it, make it as good as you can in the first place.