Patent Application
20050024210
1. Field of the Invention
The present invention relates to a perimeter intrusion detection system with integrated sensor cable. More particularly, the present invention relates to a security sensor system, with a specific cable configuration, for locating a disturbance along the length of the sensor cable and for providing intrusion data through a further use of the sensor cable.
2. Description of the Prior Art
In the field of outdoor intrusion detection systems, there are many security systems for sensing disturbances along a distributed sensor cable deployed about a perimeter. These systems face certain challenges not found in indoor security situations. Environmental conditions, such as temperature extremes, rain, snow, animals, blowing debris, seismic effects, terrain and traffic, must all be taken into account. When functioning under these adverse conditions, the system must continue to maintain a high probability of detection while minimizing false alarms (alarms with unknown causes) and nuisance alarms (environment-related alarms), both of which may compromise and reduce the performance of the security system.
Fence and wall-associated sensors are above-ground detection sensors that are attached to an existing fence or wall. They detect intrusion when an intruder disturbs the detection field, or when strain or vibration due to cutting or climbing on a metal fabric fence triggers an alarm. IntelliFIBER™ is a fiber-optic based fence-disturbance sensor for outdoor perimeter security applications from Senstar-Stellar Corp., of Carp, Ontario, Canada. This prior art fiber optic sensor can detect intruders cutting, climbing, or lifting fence fabric, and it provides protection circuitry against electromagnetic interference, radio frequency interference, and lightning. The system includes a programmable microprocessor that processes signals based on the changes in optical parameters generated as a result of disturbances in proximity to the distributed fiber optic sensor cable. The microprocessor allows the user to calibrate and set operating parameters for specific zones/environments. Alarm processing optimizes detection and minimizes nuisance alarms from wind, rain, snow, fog, animals, debris, seismic activity, and the like.
In many security systems, one important characteristic which is useful to determine in conjunction with suitable processing means, is the location of the disturbance along the length of a sensor cable. Such a characteristic is commonly known in the art as “ranging”. Ranging is useful both to identify the intruder, but also to locate and rectify locations where nuisance alarms are generated, for example a loose sign banging on the fence.
In any intrusion detection system, the ability to minimize false or nuisance alarms is enhanced when better information on the intrusion event is obtained. Hence, location data, and/or simultaneous data from two or more detection phenomenologies, is useful data to fuse for processing to further obtain either a higher probability of detection, a lower false alarm rate (FAR), a lower nuisance alarm rate (NAR), or a combination.
In the prior art, there are various security systems having a ranging capability. For instance, U.S. Pat. No. 5,446,446,issued to Harman, discloses a transducer cable for detecting the location of a sensed disturbance along the length of the transducer cable. A “driving” signal is imposed on the transducer cable in order to obtain a response signal. According to Harman, the location of the intruder is determined from the detected response signal. While ranging capabilities of a transducer cable are taught by Harman, the specific transducer cable design is costly, and only allows detection by a single means, namely an impedance change. In another related U.S. Pat. No. 5,448,222, a single means is also disclosed.
Another Harman published patent application, US 2002/00441232, discloses a cable guided radar system for the detection and location of an intruder. The cable system comprises a pair of leaky coaxial cables coupled to an RF transceiver which is in turn coupled to a processor. However, the dual leaky coaxial cable structure is very expensive to produce, requires the generation and reception of an external electromagnetic field, and provides only a single detection signal caused by the motion of a target in the field. Additionally, sensing a target within an external field has not been found to be a practical application for mounting on metal structures, such as fences, nor typically above ground such as on walls.
The U.S. Pat. No. 5,705,984, issued to Wilson, discloses a sensing system with a deformable sensor cable utilizing a reflectometer to measure the reflected signal. The deformable sensor cable of the Wilson patent discloses a ranging capability where an RF signal is injected along the sensor cable and the reflected signal measured. However, a deformable cable requires that the cable be compressed to detect an intrusion rather than sensing movement of the conductor. In the U.S. Pat. No. 3,846,780, issued to Gilcher, while a loose centre conductor in tube is disclosed, a sensor cable system with a ranging capability is not provided. Neither reference discloses a dual use sensor cable for ranging and for processing of detection data, as well as a suitable cable configuration for such dual purposes.
In view of the above-noted shortcomings, the present invention seeks to provide an intrusion detection system (IDS) with an integrated sensor cable having a multi-purpose application to provide additional intrusion data in a security sensor system. In addition, the present invention seeks to provide a sensor cable utilized for ranging purposes in combination with at least one parallel passive or active sensor cable utilized for intrusion detection purposes, to form an integrated sensor cable.
The present invention provides an intrusion detection system (IDS) which provides the function of an “active” ranging sensor cable system utilized for identification of the location of the intruder, with that of a known “active or passive” cable detection system, in an integrated cable configuration. This dual function is provided in conjunction either with a single conventional sensing cable applied in a novel manner, or in combination with other parallel sensing cables to form a functionally integrated sensor cable. The integrated sensor cable is coupled to an IDS processor and utilized by the IDS to achieve a dual functionality. In terms of the first function, an “active” ranging cable component includes a shielded coaxial sensor cable having a loosely disposed conductor. A signal pulse is injected into one end of this cable. When an intrusion disturbs the sensor cable, and hence alters its capacitance, or impedance at the intrusion location, the reflection of the signal pulse will be altered. A measurement of the reflection at the same cable end by a receiver and processor provides timing information relative to the pulse injected. Hence, the processor identifies the location of the disturbance based on the return time of the reflection along the sensor cable. Such a time-based sensing of cable impedance changes versus distance is conventionally performed by a Time Domain Reflectometer (TDR) function.
Regarding the second function, the single conventional sensing cable or an additional parallel cable, also in combination with the processor is used to sense intrusion disturbances, by another sensing phenomenology, in order to provide additional intrusion data. For a passive use of the functionally integrated sensor cable using a single conventional sensing cable, the conventional sensing cable must be constructed to generate a terminal voltage in response to an intrusion disturbance. The processor then generates a signal in response to the voltage produced by the conventional sensing cable.
The overall processing means monitors the reflection of the signal pulses from the ranging cable component, and also the passively sensed signal either received from the single cable or the parallel sensor cable. The signals generated by the processing means provide intrusion location and other characteristics in order to detect and classify the intrusion. The detection and classification of intrusions by combining data from multiple sensors is commonly termed in the art, sensor fusion.
For further clarity, the additional parallel cable is not necessary to provide the dual sensing function of the present invention. If the coaxial cable having a loosely disposed conductor is sensitized to detect via some other sensing phenomenology such as the triboelectric effect, the same cable can then be used both actively for range information and passively for triboelectric effect sensing. Such is the case when used in conjunction with the sensor cable of the proprietary Intelli-FLEX™ system of Senstar-Stellar Corp. Cables with one or more loose conductors from other manufacturers, and using other sensing phenomenologies could potentially be utilized or adapted for the dual function. Other such sensing phenomenologies could include magnetic, piezoelectric, electret, and the like, and may be utilized without straying from the intended scope of the present invention.
The present invention is also advantageous in that the sensor cable system may be further integrated with other parallel components to provide intrusion information such as ranging in a fence-mounted application to monitor the perimeter of the fence, as well as power distribution and other functionalities in a single sensor cable.
In a first aspect, the present invention provides an intrusion detection system comprising a coaxial cable having a first electrically conductive cable member, a second electrically conductive cable member, and an electrical insulating member disposed between the first cable member and the second cable member, the first cable member being loosely disposed in the coaxial cable and thus freely movable relative to the insulating member to provide an impedance change in response to a disturbance, and the coaxial cable capable of producing a terminal voltage in response to the disturbance, and a processing unit, operatively coupled to the coaxial cable, for propagating an injected signal into the coaxial cable and receiving a reflected signal altered by the impedance change along the coaxial cable, and locating the disturbance based on a timing differential between the reflected signal relative and the injected signal, in an active state, and for generating a signal in response to the terminal voltage produced from the coaxial cable, in a passive state.
In a second aspect, the present invention provides an intrusion detection system comprising an integrated sensor cable having an input and an output, the sensor cable having a primary cable having a first electrically conductive cable member, a second electrically conductive cable member, and an electrical insulating member disposed between the first cable member and the second cable member, the first cable member being loosely disposed in the primary cable and thus freely movable relative to the insulating member, to provide an impedance change in response to a disturbance and at least one secondary sensor cable capable of producing a response to the disturbance, and a processing unit, operatively coupled to the input side and the output side of the integrated sensor cable, for propagating an injected signal and receiving a reflected signal altered by the impedance change along the primary cable, and locating the disturbance based on a timing differential between the reflected signal and the injected signal, in an active state, and for generating a signal based on the response from the at least one secondary sensor cable, in a passive state, wherein the primary cable propagates there along an injected signal from the processing unit.
In a third aspect, the present invention provides an intrusion detection system comprising an integrated sensor cable having an input and an output, the sensor cable having a coaxial cable having a first electrically conductive cable member, a second electrically conductive cable member, and an electrical insulating member disposed between the first cable member and the second cable member, the first cable member being loosely disposed in the coaxial cable and thus freely movable relative to the insulating member, to provide an impedance change in response to a disturbance, and capable of producing a terminal voltage in response to the disturbance; a reflectometer for propagating an injected signal and receiving a reflected signal altered by the impedance change along the coaxial cable, a processor for generating a signal in response to the terminal voltage produced from the coaxial cable and switching means being coupled to the processor and the reflectometer for alternating in a time sequence between the processor and the reflectometer, wherein the switching means is coupled to the input and the output of the integrated sensor cable, and wherein the processor is coupled to the reflectometer for locating the disturbance along the integrated sensor cable based on a timing differential of the reflected signal relative to the injected signal.
In a fourth aspect, the present invention provides an intrusion detection system comprising an integrated sensor cable having an input and an output, the sensor cable having a primary cable having a first electrically conductive cable member, a second electrically conductive cable member, and an electrical insulating member disposed between the first cable member and the second cable member, the first cable member being loosely disposed in the primary cable and thus freely movable relative to the insulating member, to provide an impedance change in response to a disturbance and at least one secondary cable capable of producing a terminal voltage in response to the disturbance; a reflectometer, coupled to the input of the integrated sensor cable, for propagating an injected signal and receiving a reflected signal altered by the impedance change along the primary cable and a processor, coupled to the input and the output of the sensor cable, for generating a signal in response to the terminal voltage produced from the at least one secondary cable, wherein the processor is coupled to the reflectometer for locating the disturbance along the integrated sensor cable based on a timing differential of the reflected signal relative to the injected signal.
In a fifth aspect, the present invention provides an integrated sensor cable for use in an intrusion detection system having a processing unit, the sensor cable having an input and an output, both the input and the output of the sensor cable for coupling to the processing unit for locating a disturbance along the sensor cable and for generating a signal in response to the disturbance, the integrated sensor cable comprising a coaxial cable having a first electrically conductive cable member, a second electrically conductive cable member, and an electrical insulating member disposed between the first cable member and the second cable member, the first cable member being loosely disposed in the coaxial cable and thus freely movable relative to the insulating member, to provide an impedance change in response to the disturbance in an active state, and the coaxial cable capable of producing an terminal voltage in response to the disturbance, in a passive state.
In a sixth aspect, the present invention provides an integrated sensor cable for use in an intrusion detection system having a processing unit, the sensor cable having an input and an output, both the input and the output of the sensor cable for coupling to the processing unit for locating a disturbance along the sensor cable and for generating a signal in response to the disturbance, the integrated sensor cable comprising a primary cable having a first electrically conductive cable member, a second electrically conductive cable member, and an electrical insulating member disposed between the first cable member and the second cable member, the first cable member being loosely disposed in the coaxial cable and thus freely movable relative to the insulating member, to provide an impedance change in response to the disturbance and at least one secondary cable, for passive disturbance sensing capable of producing a passive response to the disturbance.
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.
For the purposes of this document, the “active ranging” cable system is one where a signal is injected (transmitted) into the cable, and a response signal, either unmodified or modified by an intruder, is sensed by a receiver and analyzed by a processor to determine range or location of the intrusion, similar to radar. For example, the injected signal to a loosely disposed conductor cable could be a pulse, and the reflected signal from an intruder altering the impedance of the cable is captured at the same cable end and analyzed; e.g., time relative to the input pulse is used to obtain location, amplitude or frequency to classify the intruder as a valid target.
Also for the purposes of this document, in a “passive” cable system, there is no signal injected by a transmitter, rather it is created on the sensor cable itself by the disturbance, such as in triboelectric, piezoelectric and electret cables. The signal is received and analyzed as a generally continuous time response waveform of some amplitude and frequency—there is no timing data relative to an injected signal to provide location. For example with the Intelli-FLEX™ system the sensor cable is constructed with suitable materials having triboelectric properties, to produce a small voltage between inner and outer conductors in response to local cable flexing, from the presence of the intruder.
It is also understood that the classification of “passive, or passive sensing, or passive disturbance sensing” systems includes those cable systems that require some excitation signal applied to the sensing cable to provide the passive sensing signal to analyze. These systems as such do not generate a voltage signal on their own, for example magnetic or fiber optic cables.
For example with the IntelliFIBER™ system, a signal input is a continuous optical signal applied at one end of the fiber cable. The system receives a signal at the other end of the fiber cable which has its polarization altered by the intruder's presence. The optical output signal is converted to a voltage response very similar to the passive sensed output of the Intelli-FLEX sensor. This system does not provide location data, as there is no timing element nor reflection data provided with sensing at the opposite cable end. Accordingly, the present invention may be incorporated into such a system, as a passive sensing system with a converted voltage output relative to the disturbance.
Also for purposes of this document there are some conductor cable sensors that are generally coaxial but may have additional conductors within their structure, such as magnetic sensing cables, and may be incorporated in such a system.
Referring now to
An alternative construction is possible where the outer conductive shield member 3 could be the loose conductive cable member relative to the insulating outer tube 4, whereas the inner sense conductor 5 is not free to move relative to the outer tube 4. Alternatively, it is possible that the insulating tube 4 be “floating”, loosely disposed between both conductive members 3, 5.
A reflectometer may be coupled to the cable 1, such as the Time Domain Reflectometer (TDR) 100 shown pictorially in a further
To further explain, a TDR is utilized to interrogate the cable by propagating a pulse down the cable. When the pulse reaches an impedance change along the cable, a portion or all of the pulse energy is reflected back dependent on the size of the impedance change from the cable's characteristic impedance. The TDR measures the time it takes to travel down the cable to the disturbance where the impedance change occurs, and back along the cable. The TDR then forwards the reflected signal information to a processor or to a display. This implementation of the TDR, coupled to a sensor cable, is in an “active” state to provide an “active ranging” cable system. Alternatively, a cable may be coupled to a processor in a “passive” state is to provide a “passive” cable system. In a “passive” state, the processor would measure a voltage change, with appropriate additional circuitry in some cases, as a time response function generated on the cable in response to a disturbance. In an embodiment of the present invention, both the passive cable system and the active cable system may be integrated to provide both the passive and the active states of cable sensing.
In
It should be mentioned that the integrated security sensor cable 10 may contain a single coaxial cable such as loose-wire-in-tube triboelectric transducer cable 1, described with reference to
The second jacket 20 contains two fiber optic cables 50a, 50b. While only two fiber optic cables 50a, 50b are shown, the skilled artisan will understand that the fiber optic cables may be in the form of cabling bundles with multiple individual fibers in the second jacket 20, or fiber optic cable ribbon, or the like. At least one of the two fiber optic cables 50a, 50b is an optical sensing fiber. According to the present invention, an optical sensing fiber is utilized to generate a response to a sensed disturbance in proximity of the sensor cable 10. It should be noted that the optical sensing fiber or adjacent fibers may be further utilized in transmitting secure data signals, i.e. both optical sensing signals and secure data signals can be multiplexed along a single optical sensing fiber. The third jacket 30 contains power conductor cables 60a, 60b, and an auxiliary data cable 60c such as coaxial cables, twisted pairs, . . . etc. The overjacket 40 defines a secure area having a diameter that is wide enough to contain the first jacket 15, second jacket 20 and the third jacket 30.
It should be mentioned that the ranging sensor cable 17 may also be coupled with any other linear sensing cable that does not directly provide an easily measured impedance change and likely requires at least two cables in total, one ranging sensor cable, such as a transducer cable, and one non-ranging sensor cable, i.e., piezoelectric, electret, magnetic, fiber optic etc. While the use of such cables is likely more costly and adds complexity in processing signals, these cables would be suitable for the purposes of the present invention. In a further embodiment shown
The utilization of a bundled jacket structure, as in
As the integrated security sensor cable 10 of the present invention may be buried in the ground, the sensor cable 10 may require a rodent resistant layer along the overjacket 40. It is conceivable that the same security sensor cable may be partly buried in the ground and partly running above ground on a given structure, such as, but not limited to fences, walls, or gates.
According to one embodiment of the present invention, the fiber optic cables 50a, 50b, may be standard commercial fiber optic cables selected for their detection or data communications properties. The integrated security sensor cable 10, which would include the ultraviolet resistant overjacket, may be further attached to a fence by means of ultraviolet resistant cable ties (not shown). One or more of the fiber optic cables 50a, 50b will communicate optical signal changes, based on minute flexing of it, when an attempt is made to cut, climb, or lift fence fabric for example, or more particularly to disturb the sensor cable 10. In this embodiment, the third jacket 30, of
The combination of an “active” sensor cable, in a first jacket, and a “passive” sensor cable, in a second jacket, enables the security system to provide a dual functionality of actively ascertaining the location of the disturbance while passively sensing disturbances. As well, by further combining the second power conductor cables and auxiliary data cables, both power and data transmission are also provided along the sensor cable. The possible use of the third jacket 30, and the data cables therein, provides additional or alternative data transmission means through the sensor cable 10. As such, the sensor cable 10 may provide multiple functions if implemented in a security sensor system. For example, the data cable 60cmay provide audio or video signals throughout a security system while the fiber optic cables 50a, 50b would transmit other data signals.
In
Further in
In this implementation of the present invention, a further consideration is thresholding and zoning for determining the presence and location of an intruder. For example, it may be useful to electronically define zones or range bins, that correspond to features of the perimeter where the cable is deployed, such as corners of buildings or gates, in order to activate video assessment or response forces. These zones, or a subset of these zones, may have respective detection thresholds set by a calibration procedure, for example, setting a low threshold in an area where the intruder detection is low (e.g., a very stiff fence), or high for a fence section that provides a large intrusion response.
As shown in
The sensor cable 10 may be coupled to either a time or frequency domain processor 110 in order to perform the dual functionality of detection and location within one processor having an integrated transmitter/receiver unit (not shown). Thus, the TDR 100, as a separate unit, is not required in the intrusion detection system 99 but rather its function integrated into the processor 110. The TDR function generally encompasses a method of creating a pulse, injecting it into the cable, and receiving and processing the time-response reflected signal from a cable to monitor signal changes as a function of distance. Thus, the processor 110 could utilize, for example, a directional coupler for separating the transmitted and reflected signals, or a reflection bridge, dependent on the type of signals injected and the application.
Techniques such as range bins with individual intrusion thresholds set on each bin to improve the signal to noise ratio (SNR) could also be utilized by the processor 110. As described earlier, the processor 110 could implement various ranging approaches. In one such implementation, a “wideband” cable input may be applied to the sensor cable, and a frequency domain processing applied to the return signal in order to determine disturbance location.
In
Referring now to
In one specific embodiment of the present invention, the integrated sensor cable may be utilized in conjunction with the proprietary Intelli-FLEX™ system, which uniquely uses triboelectric cables. Such a system currently senses via the triboelectric charge produced by flexing or motion of the cable to determine the presence of an intrusion, and additionally produces a continuous signal output over a frequency band that includes an audio band, to “listen in” on the intruder response. By utilizing a time-domain reflectometer component, as described earlier—coupling to either end of the sensor cable 10—the impedance change, along a triboelectric cable, may also be sensed to determine the precise location of a disturbance.
The Intelli-FLEX™ system may be further implemented in existing systems to provide location with only an additional hardware component. For example the TDR function could be implemented as a daughtercard, in accordance with the present invention or could alternatively be replaced with a frequency domain approach, and potentially provide further SNR improvements. In addition, a Sensitivity Time Controller (STC) may be utilized in conjunction with the TDR to improve the SNR by varying gain corresponding to the received signal timing.
According to the present invention, there are various time and frequency domain methods that exist and could be applied for determining range. These typically are described in radar texts, once a method of producing a reflection corresponding to the target location is devised related to the transmit and receive elements, being antenna, leaky cables, or in this case shielded coaxial cables. Similarly, parameters of these can be optimized for the application, for example the pulse duration can be shortened to improve target location accuracy with a time-domain reflectometry approach, or the bandwidth of a frequency modulated injected signal increased in a frequency domain approach.
In another embodiment, a dual integrated sensor cable may also form part or be deployed in conjunction with of the sensor cable utilized in the IntelliFIBER™ system of Senstar-Stellar Corporation or other manufacturers such as those produced by Fiber SenSys, Inc, of Beaverton, Oreg., US or by Future Fibre Technologies Pty. Ltd., Rowville, Victoria, Australia. The integrated sensor cable may be positioned within a secure cable jacket to provide enhanced intrusion detection including intruder range.
The present invention may be further implemented as an integrated sensor cable system, where further power cables, and copper or fiber-optic communication cables are also included in the integrated sensor cable. It is also understood that other sensing phenomenologies, including magnetic, piezoelectric, electret, and the like, may be utilized without straying from the intended scope of the present invention.
Dependent on the two cable phenomenologies, different inputs or outputs of the cable may be used for different functions or at different times. For example with the Intelli-FLEX™ application the reflectometer function may be performed at one end of the cable in a time sequence between which the same or other end of the cable is passively sensed for the triboelectric effect. Ideally, the cable end not being sensed is terminated appropriately, e.g., with its characteristic impedance for the TDR function, or a high impedance for the triboelectric effect. Similarly, the IntelliFIBER™ injects an optical signal in one end of a fiber and receives on the opposite end.
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.
