Showing papers on "Intrusion detection system published in 1977"

Pre-intrusion detection device

Abstract: An intrusion detection apparatus includes a capacitance having an "active" field, the coupling increases substantially when an intruder is related by conduction with a door handle. The apparatus is suspended from the inside handle of the door and is arranged so that the door handle is the transmitter element the capacity, while a separate plate constitutes the receiver element of the capacity. The capacity field is maintained under load by an oscillator operating with a battery and whose frequency and amplitude are substantially constant. The intrusion detection system is integral and is not set to land from the outside by the intruder. The part of the signal receiving circuit includes an amplifier whose output is squared, and also has means for adjusting the reference level with which the signal is compared.

Receiver for a HF-intrusion detection system

Abstract: A receiver in which the detection sensitivity of a detection diode is adjustable as a function of the polarization current, and is controlled by means of a feedback circuit provided with a delay element so that changes in the received signals having a frequency below a value determined by the delay element are eliminated.

Perimeter intrusion detection and assessment system

Abstract: To obtain an effective perimeter intrusion detection system requires careful sensor selection, procurement, and installation. The selection process involves a thorough understanding of the unique site features and how these features affect the performance of each type of sensor. It is necessary to develop procurement specifications to establish acceptable sensor performance limits. Careful explanation and inspection of critical installation dimensions is required during on-site construction. The implementation of these activities at a particular site is discussed.