A signalling tag of the type used in house arrest systems has a tamper detection device for detecting removal of the tag from the monitored person. The signal is set to a tamper condition upon removal. The tamper detector can only be reset to the normal state by a reset signal which incorporates a characteristic...http://www.google.com.au/patents/US5075670?utm_source=gb-gplus-sharePatent US5075670 - Personnel monitoring tag with tamper detection and secure reset
