| 摘要 |
The invention relates to a two-mode intrusion detection system which comprises: (A) a plurality of magnetic sensing units, connected in chain-like manner and spaced apart from one another, each sensing unit comprises: (a) a magnetic sensor s for sensing a 3-D magnetic field vector of the Earth; (b) an accelerometer for sensing a 3-D acceleration vector evolving from the acceleration g of the Earth; and (c) first communication means for conveying said sensed 3-D magnetic field vector and said sensed 3-D acceleration vector to a proximate processing unit; B. one or more processing units, each processing unit comprises (a) second communication means for communicating with one or more of said magnetic sensing units; and (b) a processor for: (B.1.) during a calibration mode, receiving from each sensing unit respectively said magnetic field vector of the Earth as measured by its respective magnetic field sensor s, and said acceleration vector as measured by said accelerometer a, and determining, based on said magnetic field vector and said acceleration vector the respective orientation of each magnetic unit with respect to a predefined coordinates system; and (B.2.) during an intrusion detection mode receiving periodically from two or more sensing units magnetic field measurements as measured respectively by corresponding magnetic field sensors s, and based on said two or more magnetic field measurements, and the known orientations of the respective magnetic units, as determined by said calibration mode, determining whether an intrusion has occurred and the location of said intrusion. |
