| 摘要 |
A detection system designed primarily for detecting intruders of fenced-in areas such as yards, compounds, factory areas and the like. In the preferred embodiment, a chain-link metal fence extends about the area being monitored. A conductive cable extends parallel to the fence either on its inner or outer side. The cable is spaced uniformly from the fence which functions as an electrical ground. The cable is selected with a dimension and is spaced at a distance such as to establish uniform characteristic impedance between the cable and the grounded fence with the characteristic uniform impedance preferably in the order of 100 to 1,000 ohms. The cable is connected to a pulsing circuit and receiver so that the cable may be pulsed and reflections or partial reflections of the pulse signal received and displayed on an oscilloscope which is calibrated for a visual display and indication of the cable being monitored. Movement of people over or adjacent to the cable or the severing of the cable cause immediate mismatches which are reflected and suitably displayed on the oscilloscope at a location corresponding to the occurrence of the mismatch.
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