| 摘要 |
A security system is provided comprising at least a linear sensor 106,108 and a controller 104 attached to the linear sensor. The controller is configured to detect a break in the linear sensor; determine the geographical position of the controller; and transmit a message including an indication of the geographical position of the controller if a break in the linear sensor is detected. The controller may further determine the length along the linear sensor at which the break has occurred. The controller may utilise time domain reflectometry to determine the length along the linear sensor. The transmitted message may further include an indication of the position of the break in the linear sensor. The linear sensor may comprise a twisted pair of wires (see figure 2), each wire having a polyethylene foam coating, and a resistance connected between ends of the pair of wires distal to the controller. A value of an electrical property of the linear sensor may be read in order to detect a break in the linear sensor. The electrical property may indicate an open circuit condition of the linear sensor. |
