| 摘要 |
<p>A wire comprised of an electrical conductor enclosed within insulation, is loosely positioned relative to an electrically conductive member. This combination is positioned to monitor disturbances caused by the intrusion of the protected area. The relative movement of the wire and the electrically conductive member caused by intrusion disturbances produces an electrical signal which is attributable to a capacitance change. The signal can be realized from either the electret characteristic of the wire or it can be realized by the application of a d-c bias voltage to the combination. A signal developed by the combination in response to a mechanical disturbance includes a low frequency and a high frequency component. The low frequency component, attributable to a "strain mode" of operation, developed by the displacement of the wire relative to the electrically conductive member by mechanical deflection of the conductive member whereas the high frequency component, attributable to an "acceleration mode" of operation, results from the vibration of the wire relative to the conductive member. The high frequency component code is comparable to a "ringing" condition much the same as is experienced by an accelerometer.</p> |
