| 摘要 |
An alarm locator module for use in association with a picket fence having a plurality of picket elements disposed along a tubular rail, each picket being armed with an intrusion detection device connected to a three line supervised conductive loop contained within said rail and in constant communication with the intrusion locator module. The intrusion locator module supplies voltage and current down a first line of the loop, having a plurality of resistive elements disposed in spaced apart relationship along a portion of its length. Current normally flows back up the loop via a return line to ground, unless an intrusion is detected, in which case the intrusion detection device causes a short between the first line and a second line of the loop thereby causing current to flow through the second line back to the intrusion locator device, which is capable of detecting and reporting the intrusion. Multiple intrusions cause an increase in current in the first line, which may be detected and measured to determine the distance between the first and last intrusions on the fence. An open circuit on any of the three lines halts the flow of current on the particular line affected and may also be detected. Location of a single short can be calculated by polling the voltage on the second line provided an open circuit has not also occurred.
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