| 摘要 |
The wireless detection system has a number of electronic tickets (B) with transmit/receive modules and at least one terminal (AP) associated with a detection zone (20). Communications between the tickets and terminal are initiated by a broadcast message (BMSG) from a terminal, a ticket receiving it sends a presence message (PMSG) following a delay determined by its identity and the terminal acknowledges this with a message (AMSG) with the ticket identity. Collisions are corrected by resending the presence message if the acknowledgement signal is not received for a period dependent on the ticket interval. |
