A method and system is presented for tracking patient motion in image guided surgery, using skeletal reference structures instead of fiducial markers. To do so, the system reconfigures a communication channel used to contact the target entity such that the system can intercept a communication from a source contacting entity en route to the target entity. Further, the production demand information and the recyclable part availability information are referenced to generate a procurement plan on parts and materials that cannot be fully supplied from available, recyclable parts alone. The signal processing circuit performs successive approximation based on the comparison output voltage signal to generate the digital output data.