Ingress-egress monitoring system

A system for monitoring ingress into or egress from a specified area, the ingress-egress monitoring system being characterized in that the system comprises:

• transmitters disposed respectively at a plurality of ingress-egress gates of the specified area for emitting radio waves to the respective gates,
• tags to be attached to respective persons to be checked for ingress or egress and each adapted to transmit an identification signal containing an ID code of its own in response to radio waves received from the transmitter,
• receivers disposed respectively at the ingress-egress gates for receiving the identification signal from the tag and each operable to output a monitoring signal containing the ID code contained in the identification signal and the number of the gate of its own, and
• a monitor connected to the receivers for detecting an incidence of ingress into or egress from the specified area based on the monitoring signal output from the receiver,
• the tags to be attached to the respective persons being operable to transmit the respective identification signals in cycles different from one another,
• wherein the cycle for which each of the tags is set is so adjusted that the receiver at the gate passed through is capable of receiving the identification signal a plurality of times from the same tag.