Multiple broadcasting tag and monitoring systems including the same

An improved transmitting tag for enhancing the tracking and locating capability of a monitoring system and for allowing control over accessibility to particular zones and/or equipment within a restricted area. The tag is provided with a transmitter of multiple broadcasting signals for allowing periodical broadcasting of at least two signals of different strength at different time intervals and preferably of different information content. The signals carry the tag identification code and a strength identification code. The weak signals emitted by the tag can be further exploited for allowing or denying accessibility to local operating systems.