Some embodiments includes RFIDs capable of activating an observable indicator upon receiving an indicate signal. Some embodiments includes RFIDs capable of activating an observable indicator based on a position of a manually operated switch. Some embodiments include interrogators capable of verifying...http://www.google.com/patents/US20080186178?utm_source=gb-gplus-sharePatent US20080186178 - RFIDS, interrogators, indication systems, methods of determining a bi-directional communication range of an interrogator, methods of activating an observable indicator, and methods of indicating bi-directional functionality of a radio connection
