公开(公告)号：US4887069A

公开(公告)日：1989-12-12

申请号：US116587

申请日：1987-11-04

申请人： Melvin C. Maki ,  Walter J. Feller ,  Edward L. Adams

发明人： Melvin C. Maki ,  Walter J. Feller ,  Edward L. Adams

IPC分类号： G08B13/24

CPC分类号： G08B13/2497

摘要： An intrusion detection system of the type using cables arranged along a perimeter to be protected and sensing changes in the electrical field around the cables caused by the presence of an intruder. The cables are divided into sections or blocks and typically only one of the sections is energized at any time. The variations caused by an intruder at the selected sections are transmitted through the intervening section to the receiver portion of a transceiver located at one end of the cables. This indicates in which section intrusion has occurred. The system uses continuous wave excitation whereby the expense and complexity of high speed switching and timing of r.f. signals are avoided.