摘要:
An intrusion detection system of the type using cables arranged along a perimeter to be protected and sensing changes in the electrical field around the cables caused by the presence of an intruder. The cables are divided into sections or blocks and typically only one of the sections is energized at any time. The variations caused by an intruder at the selected sections are transmitted through the intervening section to the receiver portion of a transceiver located at one end of the cables. This indicates in which section intrusion has occurred. The system uses continuous wave excitation whereby the expense and complexity of high speed switching and timing of r.f. signals are avoided.
摘要:
An intrusion detection system using waves guided by the conductive outer sheath of a coaxial cable. An r.f. signal from a transmitter is supplied between the inner conductor and outer conductor or shield in conventional fashion. Coupled wave devices are spaced along the cable; each coupled wave device transferring r.f. energy between a transmission mode within the cable and a guided mode propagated along the exterior of the conductive outer shield. In one embodiment a second coaxial cable similarly provided with coupled wave devices is spaced from the transmitter cable and has one end connected to a receiver. The change in r.f. coupling between the cables caused by an intruder produces variations in the r.f. energy coupled to the second cable which is detected at the receiver. Alternative embodiments include the use of a single cable with coupled wave devices adapted for both transmission and reception. Further alternative configurations include the use of a leaky coaxial cable, preferably buried, operating in combination with a cable provided with coupled wave devices. In some circumstances a single elongated conductor can support the guided mode. The guided mode can be established in the outer shield or single conductor by an external source and need not always be coupled from the cable interior.
摘要:
A simulated target for use in conjunction with detection systems using coupled transmission lines. The simulated target is positioned in the vicinity of the transmission line and the response used both to monitor system operation and to calibrate system response levels. The simulated target can be of a type having its electrical length variable under system control or can be purely passive serving to alter the stationary response profile of the system.
摘要:
The present invention provides an inexpensive security sensor cable, a method for manufacturing of same and an overall security system for using that sensor cable. The sensor cable consists of a central conductor, an air separator, a polyethylene dielectric tube, an outer conductor and an outer protective jacket. The central conductor is loosely centered in the coaxial cable and thus freely movable relative to the dielectric tube. The sensor cable has application either in a passive sensing system or in an active ranging sensing system to determine the location of an intrusion along the cable. For the passive sensing function, when the center conductor moves, it contacts a suitable dielectric material from the triboelectric series, such as polyethylene, which can be processed to produce a charge transfer by triboelectric effect that is measurable as a terminal voltage. In an active system, the central conductor moves within the dielectric in response to a vibration to provide an impedance change that can be sensed. Conventional radio grade cable may be modified in its construction by removing its dielectric thread to manufacture the sensor cable, thus enabling the center conductor to move freely in the air gap within the dielectric tube. An inexpensive method of manufacturing sensor cable is provided as the cable parts are readily available. Such a sensor cable is advantageous in that the passive triboelectric properties of the cable, in response to a disturbance, can provide a larger voltage response over prior art cables.
摘要:
A leaky coaxial cable is designed to produce a defined coupling between its interior and exterior. A bonded and insulated outer conductor of relatively large width relative to the cable diameter, is spirally wound at a low pitch angle to provide at high frequencies a coupling level having minimal effect on the coaxial properties of the cable.
摘要:
The present invention provides an inexpensive security sensor cable, a method for manufacturing of same and an overall security system for using that sensor cable. The sensor cable consists of a central conductor, an air separator, a polyethylene dielectric tube, an outer conductor and an outer protective jacket. The central conductor is loosely centered in the coaxial cable and thus freely movable relative to the dielectric tube. The sensor cable has application either in a passive sensing system or in an active ranging sensing system to determine the location of an intrusion along the cable. For the passive sensing function, when the center conductor moves, it contacts a suitable dielectric material from the triboelectric series, such as polyethylene, which can be processed to produce a charge transfer by triboelectric effect that is measurable as a terminal voltage. In an active system, the central conductor moves within the dielectric in response to a vibration to provide an impedance change that can be sensed. Conventional radio grade cable may be modified in its construction by removing its dielectric thread to manufacture the sensor cable, thus enabling the center conductor to move freely in the air gap within the dielectric tube. An inexpensive method of manufacturing sensor cable is provided as the cable parts are readily available. Such a sensor cable is advantageous in that the passive triboelectric properties of the cable, in response to a disturbance, can provide a larger voltage response over prior art cables.
摘要:
A sensor array that forms part of an intrusion detection system, which is adapted for use on narrow spaced objects that surround a perimeter. The sensor array includes at least two intrusion detection sensor nodes, a plurality of node processors corresponding to each sensor node, and a deformable cable. The plurality of sensor nodes are situated and spaced along the deformable cable. The at least two sensory nodes include one or more discrete volumetric sensors with associated volumetric detection fields extending from each discrete volumetric sensor. Each sensor node has a detection zone extending transversely to the longitudinal direction of the deformable cable at the sensor node and defined by the detection fields of its constituent sensors as constructed and arranged in each sensor node. Each sensor node includes a node processor situated thereat for processing a response generated by the sensors when an intruder enters a nodes detection zone. An array processor of the sensor array can be coupled to each node processor to receive and process alarm disturbance signatures from each node processor.
摘要:
An intrusion detection system provides the function of an “active” ranging sensor cable system utilized for identification of the location of the intruder, with that of a “passive” cable detection system, in an integrated cable configuration. This dual function is provided with a single conventional sensing cable optimized for both “active” and “passive” sensing, or in combination with other parallel sensing cables for a “passive” cable component. The “active” cable component includes a coaxial sensor cable having a loosely disposed conductor. A signal is injected into the sensor cable such that a reflection is altered when an intrusion disturbs the cable. Based on the timing of the reflection, a processor, or a reflectometer, identifies the location of the disturbance. The “passive” cable component can be sensitized to detect intrusion via some other sensing phenomenology, such as the triboelectric effect, for triboelectric effect sensing.
摘要:
A method of manufacturing leaky coaxial cable by winding conductive tapes around a core to provide apertures of a certain shape, number and density. By varying the width of one or both tapes the aperture distribution is varied thereby altering the coupling of the cable when used in a detection system. A graded cable showing such varying coupling can be used to compensate for cable attenuation losses and other variables.