Patent Application
20050024208
The present invention relates to the field of intrusion detection systems, more particularly to an intrusion detection system for installation on or near to the top of a wall or a roof-edge.
Intrusion detection systems are frequently placed on fences, roofs or walls that provide the perimeter of a space to be protected. These systems detect the presence of an intruder and provide an alarm signal when an intruder approaches the boundary of the perimeter.
Several prior art systems exist for detecting the presence of an intruder who passes over or approaches a fence or a wall. For instance, U.S. Pat. No. 4,327,358, issued to Karas discloses a security area protection system that combines a physical deterrent barrier with an upward looking intrusion detection sensor. The intrusion sensor monitors the air space over the barrier, and comprises a corner reflector antenna that is mounted on top of and coextensive with the deterrent barrier, the sensor comprising a leaky transmission line that extends the length of the corner reflector antenna. While the Karas patent discloses a security protection system for use on a fence or wall-top, the leaky coaxial cable does not provide uniform detection close to metal objects such as a fence, and the system is not easily adaptable for use with irregularities or bends in a fence or wall surrounding a perimeter.
The U.S. Pat. No. 6,424,259 issued to Gagnon discloses an intruder detection system used to detect objects or people moving within the vicinity of a predetermined path or line. The path is defined by a distributed antenna, such as an open transmission line, alongside which, within a predetermined distance, is an array of discrete antennas spaced apart from each other. The distributed antenna and each discrete antenna define a detection zone path. A radio frequency transmitter is connected to one end of the distributed antenna and the array of discrete antennas. Connected to the other end of the distributed antenna and the array of discrete antennas is a receiver. According to Gagnon, a controller exchanges radio frequency energy between the distributed antenna and a selected discrete antenna within the array. The energy received from the selected discrete antenna is analysed to detect perturbations in the received radio frequency energy caused by an intruder moving near the path and adjacent the selected antenna. While the Gagnon patent teaches a linear array of discrete sensors for detecting an intruder in the vicinity of a line, such as a fence or wall, the arrangement disclosed by Gagnon with antennae typically 20 feet away from the wall or fence is not suitable for use on narrow spaced wall tops or roof edges that surround a perimeter.
U.S. Pat. No. 6,424,259 issued to Gagnon and U.S. Pat. No. 4,536,752 issued to Cheal both describe intrusion detection systems which include open transmission line sensors coupled to discrete antennas or receivers which are spaced along the transmission line. These intrusion detection systems each provide an array of sensing zones which are created by coupling a generally single radio frequency signal generated by a central transmitter or receiver from the cable onto the array of antennae. While the intrusion detection systems describe by Gagnon and Cheal can be used in perimeter applications, each system has limited detection features.
Other prior art systems use microwave or IR sensors to detect the presence of an intruder along a perimeter. These systems include multiple discrete sensors or transmit/receive (tx/rx) bistatic pairs that are deployed in a basket weave manner, separated by large distances, for example up to 100 m. These systems are installed on a wall-top or roof edge that surrounds a perimeter to be protected, and detect intrusion when an intruder disturbs the detection field “beam” between the two sensor heads of the pair. Limitations to the microwave systems are caused by the long start up distance for sensor beams, requiring them to be overlapped, which makes installation on walls or fences having several bends difficult. Furthermore, because the beams of the microwave systems only follow a straight line, these systems are costly to install, as each sensor must be replicated at every bend in a wall.
This invention therefore seeks to provide an intrusion detection system that detects intruders approaching a narrow object that forms a perimeter, such as a roof edge, a top edge of a perimeter wall or a building wall. The invention also provides a system which is easily installed and maintains a continuous detection zone along the perimeter, which may be curved, or have bends both horizontally and vertically.
The present invention relates to a sensor array for an intrusion detection system. According to the present invention, the sensor array includes one or more sensor nodes that are each connected to an array processor. Each sensor node includes one or more discrete sensors. These sensor nodes detect the presence of an intruder in a detection zone extending in a plane transverse to each sensor node. Whenever an intruder enters the detection zone of a sensor node, one or more of the discrete sensors of the sensor node generates a response representative of the presence of an intruder. An array processor receives the response in the form of a response signal. The array processor signal processes the response received from each discrete sensor and generates an alarm disturbance signature.
Each sensor node may further include a node processor coupled to each sensor. In this embodiment of the invention, the node processor signal processes the responses generated by the discrete sensors, and generates an alarm disturbance signature. The alarm disturbance signature is then transmitted to the array processor, which then further signal processes the alarm disturbance signature to differentiate from environmental factors such as rain or snow, or small wildlife.
The array processor may also include provisions to provide power to each of the sensor nodes from a given distribution point along the sensor array. In an embodiment of the invention, an external power source, such as a solar module or a battery/converter, may be connected to the given distribution point within the sensor array.
The sensor array of the present invention forms part of an intrusion detection system that includes a system controller and a calibration means. The system controller is coupled to the array processor and the calibration means is coupled to the system controller. The calibration means communicates with each sensor node through the system controller to adjust the sensitivity settings of the sensors of each sensor node. The system controller further processes information received from the array processor and communicates with an operator interface to provide a display map of the location of the intruder.
In an embodiment of the invention, the sensor array may be encased within an elongated housing such as an elongated duct, pipe or raceway to cause minimal visual impairment to the wall, roof top or edge. Depending on the array mounting, a detection field would normally extend upward or outward from the wall top or roof edge. In a further embodiment of the present invention, the sensor nodes may be integrated and fabricated as custom microchips, each of which may be encased within and spaced apart along a flat deformable cable or tape. In another embodiment, several linear sensor arrays may be combined end to end and distributed along a large perimeter in order to provide a large coverage length area for detecting the presence of an intruder.
In another embodiment, the sensor array may be used in an intruder detection system in conjunction with other known prior art discrete sensors that detect the presence of an intruder. By combining the sensor array with such discrete sensors, the probability that an intrusion detection system will detect the presence of an intruder increases.
The present invention is advantageous in that when the sensor array is integrated and encased within a deformable flat cable or tape, its installation on a narrow or three-dimensional surface is facilitated. The installation may be on, for example, the side or top of a building, wall, ship, dock, or fountain where an unobtrusive detection system is desired. The present invention is also advantageous in that each sensor phenomenology in a particular sensor node may be selected in order to provide different detection features, thereby enhancing the probability of detecting the presence and the location of an intruder, and differentiating a valid threat from a nuisance alarm, such as those caused by birds, small animals, . . . etc.
In a first aspect the present invention provides a sensor array forming part of an intrusion detection system comprising: a sensor array forming part of an intrusion detection system, the sensor array comprising: at least one sensor node, each sensor node having a longitudinal axis and providing a detection zone defined by a plane extending transverse to the longitudinal axis, and having at least one discrete sensor for generating a response to an intruder entering the detection zone of the sensor node; and an array processor for generating information based on processing of each response, the array processor being coupled to each of the sensor nodes.
In a second aspect the present invention provides a sensor array forming part of an intrusion detection system comprising: at least one sensor node, each sensor node having a longitudinal axis and providing a detection zone defined by a plane extending transverse to the longitudinal axis of the sensor array, and having: at least one discrete sensor for generating a response to an intruder entering the detection zone of the sensor node; and a node processor for generating an alarm disturbance signature based on the response generated by the sensor node, the node processor being coupled to each discrete sensor; and an array processor for generating information based on the alarm disturbance signature received from each node processor, the array processor being coupled to the node processor of each sensor node.
In a third aspect, the present invention provides an intrusion detection system comprising: at least one sensor array having: at least one sensor node, each sensor node having a longitudinal axis and providing a detection zone defined by a plane extending transverse to the longitudinal axis, and having: at least one discrete sensor for generating a response to an intruder entering the detection zone of the sensor node; and a node processor for generating alarm disturbance signature based on the response received from each discrete sensor, the node processor being coupled to each discrete sensor; and an array processor for generating information based on the alarm disturbance signature received from each node processor, the array processor being coupled to the node processor of each senor node; a calibration means for adjusting the sensitivity setting of each discrete sensor; and a system processor for processing the information received from the array processor and for generating an alarm condition; wherein the calibrating means is coupled to the system processor, and wherein the system processor is coupled to each sensor array.
The present invention will now be described with reference to the drawings in which:
The invention will be described for the purposes of illustration only in connection with certain embodiments; however, it is to be understood that other objects and advantages of the present invention will be made apparent by the following description of the drawings according to the present invention. While a preferred embodiment is disclosed, this is not intended to be limiting. Rather, the general principles set forth herein are considered to be merely illustrative of the scope of the present invention and it is to be further understood that numerous changes may be made without straying from the scope of the present invention.
Referring now to
It should be mentioned that there is no limitation on the number of discrete sensors that may be contained within a particular sensor node, nor the number of sensor nodes located within a sensor array. Furthermore, in the preferred embodiment of the invention, the distance between sensor nodes 10a, 10b, . . . , 10n may be selected based on several factors such as the type of intruder to be detected, the orientation of an intruder relative to the detection zone of a sensor node, the detection field of a particular discrete sensor, the range of detection of the sensor nodes, and whether the detection zones of the sensor nodes are to overlap. For example, in the embodiment of the invention in which the sensor array is mounted on a wall-top, the sensor nodes may be spaced 0.75 m apart and have detection zones that span 90 degrees in the plane transverse to each sensor node. In this embodiment, a human intruder who enters a detection zone transversely would always be detected. In the embodiment of the invention where the sensor arrays are mounted horizontally on the side of a wall, as shown in
Again, referring to
In an embodiment of the invention, the sensor array 5 may receive power from an external source such as a solar panel or battery. The external power source (not shown) would be coupled to a distribution point (not shown) within the sensor array 5, which in turn would be coupled to the array processor 30 and each sensor node 10a, 10b, . . . , 10n. The array processor 30 may also include a wireless transmission means 36 which is coupled to a wireless transmission means 46 of the system controller 45. The system controller 45 includes a means for providing bidirectional wireless communications 47 coupled to the wireless communication means 46. The calibration means 50 is connected via a wireless transmission means 51 to the wireless transmission means 46 of the system controller 45.
According to the present invention, each sensor node 10a, 10b, . . . , 10n has a corresponding detection zone 65a, 65b, 65c, shown in
It should be noted that in the embodiment of the invention where the sensor nodes 10a, 10b, . . . , 10n each include a plurality of discrete sensors 100a, 100b, . . . , 100n, each of the detection zones 65a, 65b, 65c are comprised of one or more detection fields (not shown). Accordingly, the detection zone 65a has a subset of detection fields (not shown) for each discrete sensor 100a, 101a, . . . , the detection zone 65b has a subset of detection fields (not shown) for each discrete sensor 100b, 101b, . . . , the detection zone 65c has a subset of detection fields (not shown) for each discrete sensor 100c, 101c, . . . ,. For example, if discrete sensor 100a is a microwave doppler which senses to a distance of 1 m and discrete sensor 101a is an ultrasonic sensor which senses to a distance of 2 m, then a sequential response from each discrete sensor 100a, 101a is needed for a valid alarm.
Again referring to
The array processor 30 receives the alarm disturbance signatures from each node processor 25a, 25b, . . . , 25n and signal processes the signatures in order to classify the intruder which has entered a detection zone 65a, 65b, 65c of
It should be noted that in the embodiment of the invention which includes each sensor node 10a, 10b, . . . , 10n being directly connected to the array processor 30, the array processor 30 performs all the functions of the individual node processors 25a, 25b, . . . 25n and the functions of the array processor 30 described above. Furthermore, it should be noted that the sensor array 5 may be mounted on the side of the wall 1, as shown by 5a in
It would be apparent to one skilled in the art that any commercially available wireless communication means, such as, but not limited to RF or IR, may be used for bidirectional communication between the array processor 30 and the system controller 45 or the calibration means 50 and the array processor 30. It would further be apparent that the array processor 30 may be hardwired to the system controller 45 using a commercially available cable such as, but not limited to, a ribbon cable, twisted-pair cable or a coaxial cable.
Again, with reference to
The calibration means 50 sets the thresholds or the filter parameters corresponding to each sensor nodes 10a, 10b, . . . , 10n detection zone 65a, 65b, 65c. For example, several test intrusions may be made through the detection zone 65, 65b, 65c of each sensor node 10a, 10b, . . . , 10n. The sensor nodes thresholds may be set or adjusted through a user interface, based on the results of the test intrusions, to produce a detection zone which extends out to a particular range. The parameters may be downloaded to the system controller 45, the node processors 25a, 25b, . . . , 25n and the array processors 30, and utilized in the signal processing of the responses and alarm disturbance signatures.
According to an embodiment of the present invention, the sensor, for example 100a, 101a of
Furthermore, discrete sensors may be selected to have co-located field patterns, or mutually exclusive parameters for use in fusing their outputs in processing to best determine the presence of a valid target, and eliminating nuisance and environmentally produced alarms. The discrete sensors may also be selected or their fields oriented for compatibility, for example non-interference of microwave sensors. A sensor node may be designed to produce a substantially transverse detection zone that abuts or overlaps the detection zone of an adjacent sensor node. These detection zones may also be spaced apart from each other in azimuth, elevation or range in order to provide a sequential detection zone along the sensor array.
It should be noted that the array processor 30 may be positioned anywhere along the sensor array 5. The position of the array processor 30 depends on whether the sensor nodes 10a, 10b, . . . , 10n, and the array processor 30 are connected wired or wirelessly. When the sensor nodes 10a, 10b, . . . , 10n are connected wirelessly, the position will be selected based on a line of sight between the wireless communication means (not shown) of the node processors 25a, 25b, . . . , 25n. In contrast, when the sensor nodes 10a, 10b, . . . , 10n are wired to the array processor 30, the position of the array processor 30 depends on the signal loss of the wires selected. Furthermore, the position of the array processor 30 may be selected in order to minimize crosstalk, in either the wireless or wired applications between signals being transmitted from each sensor node 10a, 10b, . . . , 10n. The position of the sensor array 5 may also be selected for line of sight between the array processor 30 and the system controller 45.
Referring to
Referring to
It should also be mentioned that the sensor array may be utilized in conjunction with a plurality of commercially available security sensors to economically cover detection gaps.
It should be understood that the preferred embodiments mentioned here are merely illustrative of the present invention. Numerous variations in design and use of the present invention may be contemplated in view of the following claims without straying from the intended scope and field of the invention herein disclosed.
