A magnetic detection system for authenticating a document includes a first magnetic scanhead adapted to create a first magnetic field for saturating the magnetization of an area on each of the bills. The magnetic detection system further includes a second magnetic scanhead with an electromagnet. The...http://www.google.com/patents/US20090090779?utm_source=gb-gplus-sharePatent US20090090779 - Magnetic Detection System For Use In Currency Processing And Method And Apparatus For Using The Same
