Showing papers on "Intrusion detection system published in 1981"

Home security system

Abstract: A security system for alerting an intrusion disturbance at an entry point to a residence, or alerting as to other emergency conditions, such as fire is disclosed. In the system, a primary monitoring unit having intrusion detection sensors for placement at entry points to a residence produces an audible acoustic alarm signal upon the occurrence of an intrusion disturbance. The acoustic signal is detected by a secondary monitoring unit which in response transmits an electronic signal through the wiring in the residence. A central monitoring unit receives the transmitted electronic signal and activates an alerting alarm and automatic telephone dialer. The system may further include a portable alarm switch for transmitting a coded radio frequency signal to the central monitoring unit to provide remote activation of an alerting device.

Capacitance intrusion detection system

Abstract: A capacitance intrusion detection system for use with a metal object or objects insulated from ground comprises a circuit for cyclically charging and discharging the object at a relatively low frequency, for example, less than 500 Hz, and simultaneously integrating the charge on the object to develop a DC voltage proportional to the capacitance of the object. The integrating network is AC coupled to a bandpass filter which passes signals having frequencies corresponding to changes in capacitance of the object caused by an intruder and these signals are applied to a threshold circuit for activating an alarm when an intrusion occurs. Tamper alarm circuits are provided to detect unauthorized disconnection of any portion of the protected object (decrease capacitance) or the addition of capacitance in an attempt to defeat the system.

Dual sensitivity intrusion detection system

Abstract: At least two circuits of sensors for detection of human presence are arranged in a protected zone and are capable of producing electric signals when they detect a human presence. In a preferred embodiment, when a human presence is detected by a first sensor circuit, the sensitivity of the sensors of the second sensor circuit is increased.

Pre-intrusion detection and alarm system

Abstract: A self-contained pre-intrusion detection and alarm system for doors and other closures, the system including an rf oscillator circuit incorporating a tank circuit which includes an antenna. The system also includes a detection and processing circuit effective to detect and amplify a change in the voltage in the rf oscillator circuit caused by a change in the antenna to ground capacitance; an audio oscillator circuit; time delay circuitry connected between the detecting and processing circuit and the audio oscillator circuit and controlling the energization of the audio oscillator circuit; and an alarm electrically connected to and controlled by the audio oscillator circuit for alerting occupants of potential danger of intrusion and also deterring potential intruders from continuing their activities toward intrusion.

Scanning seismic intrusion detection method and apparatus

Abstract: An intrusion monitoring system includes an array of seismic sensors, such as geophones, arranged along a perimeter to be monitored for unauthorized intrusion as by surface movement or tunnelling. Two wires lead from each sensor to a central monitoring station. The central monitoring station has three modes of operation. In a first mode of operation, the output of all of the seismic sensors is summed into a receiver for amplification and detection. When the amplitude of the summed signals exceeds a certain predetermined threshold value an alarm is sounded. In a second mode of operation, the individual output signals from the sensors are multiplexed into the receiver for sequentially interrogating each of the sensors. Again, if the output from any one of the sensors exceeds a certain predetermined threshold value, a stop pulse is generated which stops the multiplexer at that sensor. A third operating mode permits the operator to manually scan up and down the individual sensors in the vicinity of the output sensor which stopped the action of the multiplexer. In this manner a more precise location of the intrusion is obtained. An automatic gain control is provided for the receiver allowing the sensitivity of the receiver to be automatically adjusted for optimum sensitivity with changing background noise level.

Intrusion alarm system for preventing actual confrontation with an intruder

Abstract: An intrusion detection system is specifically designed to avoid actual confrontation within a protected premises between a returning occupant and an intruder. The system forewarns a returning owner or occupant, before entering the premises, that an intrusion has occurred by providing a signal visible from the outside of the premises. In this manner, the owner is alerted to the possibility that an intruder may still be present within the premises, and confrontation is avoided. The system includes a test mode operable from outside the protected premises to determine if the system has been tampered with by an intruder. If no intrusion signal is observed by the returning owner, he must still test the system to ascertain if the absence of the intrusion signal is a result of no intrusion, or if it is the result of an intruder having tampered with the system, by for example, removing its power supply. An "all clear" signal observable from the outside of the premises indicates that the system is in working order and has not been tampered with or otherwise dismantled during the owner's absence.

Intrusion Detection Systems

Abstract: Part 1 Security system integration. Part 2 Exterior intrusion detectors. Part 3 Interior intrusion detectors. Part 4 Alarm station monitoring systems. Part 5 Visual surveillance and alarm assessment. Part 6 Access control. Part 7 Intrusion detection system applications, public school complex nuclear reactor high-rise office building.

Design Considerations for High-Security Interior Intrusion Detection Systems

Abstract: Areas which require high security are usually those in which very valuable material, potentially dangerous material, or strategic information is stored. The primary purpose of the physical protection systems for such areas is to prevent theft or sabotage of the protected items. Intrusion detection is one of the essential elements of a physical protection system. It is essential that any new or to-be-improved intrusion detection system be carefully planned and analyzed to ensure that it will reliably perform its intended function in the specified environment and that the system's strengths and weaknesses be identified and understood. Included in the planning and analysis is the development of (a) a system philosophy, including techniques to reject nuisance alarms logically, (b) a preliminary system design, including site survey and characterization techniques, (c) on-site and off-site experiments and evaluation, including sensor test methods, (d) final system design, (e) construction and installation considerations, (f) a program schedule, (g) cost considerations, and (h) procurement. The pertinent aspects of these items for high-security interior intrusion detection systems are discussed.

Base Intrusion Schottky Barrier IR Assessment Camera Study.

Abstract: : For military base perimeter protection, sensors are being developed and deployed to provide an alarm for intrusions. These alarm systems can also provide some level of target classification, but the need to display imagery for human assessment of most target threats following an alarm is a well recognized requirement. This assessment must be accomplished with minimum delay and under both day and night illumination conditions. At night, it is desirable to avoid the use of artificial illumination, and the use of the IR spectrum for passive imaging holds great promise. Excellent IR imagery is possible with certain current equipments, but their cost has been prohibitive for deployment in perimeter defense applications. IR focal plane array (FPA) development is progressing, and this approach shows promise for significant cost reductions and increased reliability because of elimination of the need for mechanical scanning. This program is directed toward evaluation of the use of Schottky barrier technology for base security applications. Emphasis is being placed on the target assessment role, and the use of assessment cameras will also be considered in conjunction with Schottky barrier intrusion detection line sensors. The program includes coverage studies to determine requirements for array size and camera complexity to provide cost-effective coverage of base perimeters.