An apparatus for detecting movement downhole includes a first downhole component (106) having a sensor (114) coupled thereto and a second downhole component (102) positioned relative to the first downhole component (106). The sensor (114) generates a primary magnetic field that is imposed on the second...http://www.google.fr/patents/US7626393?utm_source=gb-gplus-shareBrevet US7626393 - Apparatus and method for measuring movement of a downhole tool
Apparatus and method for measuring movement of a downhole tool
