Unfortunately, I do not know enough about how to filter this noise out in software. Using shielding may be the best way to go. However, one last suggestion is using a reference signal, however, this will require knowing the frequency of what we are trying to measure.
Check out the <a HREF=http://zone.ni.com/devzone/conceptd.nsf/webmain/20B6BDBE462C6E5286256CDF00752680?opendocument>LabVIEW Lock-In Amplifier</a>. -Justin T.
