Abstract: An improved system for an anti-theft transponder includes, besides a general paged transponder an autonomous low power transmitter device capable of transmitting a specified address code for accessing at least one anti-theft transponder which includes one receiver module operating on a designated frequency used by a general coverage paging system. The transponder of the system additionally includes several modules for the tracking of the device when activated. The anti-theft transponder of the improved system is provided with a first individual access identity intended for authorization of activation by the paging system and at least a second general access identity code used for control of a direct activation within a limited coverage of the low power transmitter. A low power transmitter can also be regularly transmitting a general access identity code for a control that the item under surveillance does not illegally leave a site where it is kept.

Abstract: A transponder system is provided which presents a light weight portable or mobile system for localization of movable objects, e.g., for surveillance of valuable transports and the like. The small unit constituting the transponder contains a receiver (1) of paging type, a decoder (2), a logic unit (3), a transmitter portion (10), a built-in antenna and power supply (11). The system is controllable by an existing tested radio system for paging. One advantage of utilizing an already existing paging system is that functionality is well tested and a general covering range is obtained. In addition, costs for building up and operation of a paging system are eliminated. Control information being sent to the transponder includes a number of symbols defining a certain basic function for the built-in marker transmitter (10) and symbols which constitute control code and control data for the specific function.