Entrance security system

An entrance denial security system comprises an entrance barrier closing an entrance into a secured area having a plurality of structural tubular elements with hollow cores forming a rigid integral barrier. At least one optical fiber sensor line is laced through the hollow cores of the structural elements for detecting a fault condition signifying an unauthorized intrusion attempt. A processor in communication with the fiber sensor line generates a fault signal in response to the occurrence of a fault condition and identifying the entrance where the fault condition occurred. A communication device operatively associated with the processor communicates the fault signal and an alarm so that a proper security response can be made to the fault condition. The system further comprises a plurality of intrusion sensors disposed at certain locations. Preferably primary and secondary optical fiber sensor lines are routed through the structural elements and intrusion sensors, and primary and secondary scanning units pulse signals along the sensor lines and receive reflected signals back from the sensor lines. In the event of a cut through in the sensor lines, the primary sensor line monitors the barrier and sensors downstream of the break, and the secondary sensor line is activated to monitor the barriers and sensors downstream of the break.

BACKGROUND OF THE INVENTION

This invention relates to an entry denial security system for denying entry of a vehicle or person into a secured area and/or detecting an attempt to penetrate a barrier closing an entrance into the secured area.

With the increase in terrorism in the United States and the rest of the world, the need for an effective security system to detect and/or prevent the unauthorized entry of a vehicle and/or individual from breaking through a barrier closing an entrance into a secured area is a problem to which considerable attention needs to be given. In particular, an objective of this invention is to provide an entrance security system which detects an unauthorized opening or break through of an entrance barrier closing an entrance of the secured area.

SUMMARY OF THE INVENTION

The above objectives are accomplished according to the present invention by providing a security system for detecting an unauthorized activity and attempt to enter through an entrance of a secured area and determining the nature and location of the activity. The security system comprises an entrance barrier closing the entrance, including a plurality of hollow structural elements forming an integral barrier structure such as an entrance gate (or fixed barrier). Preferably, fiber optic sensor lines sense a first fault condition representing an unauthorized attempt to open the gate, and a severance of a structural element of the barrier. Advantageously, a longitudinal reinforcing member in the form of a solid stainless steel rod may be enclosed in the tubular elements along with the sensor lines which must be severed before intrusion. This delays intrusion after the sensor line is severed and an alarm signal generated so that ample time is provided for guard personnel too arrive before intrusion. At least one fiber optic scanning unit scans the optical sensor lines and receives scan signals in the optical sensor lines. A system computer is provided for receiving and processing the scan signals in real-time representing the condition of the optical sensor lines and generating a real-time fault signal in response to a predetermined reflection in one or more of the scan signals indicating the unauthorized activity has occurred. A communication device communicates notice of the fault signal to security personnel. Advantageously, the processing of the scan signals includes comparing the real-time scan signals to pre-established baseline scan signal which is characteristic of the first and second sensor lines, respectively, in an undisturbed, secure state.

The barrier is composed of hollow structural elements having hollow cores, and the first optical sensor line is laced through the hollow cores of the structural elements. When the barrier is an entrance gate, the gate is moveable and has an open position allowing entry and a closed position preventing entry. In this case, the system includes a sensor unit disposed relative to the entrance gate to detect movement of the gate toward the open or removed position and generate a fault signal. The sensor unit may include a reciprocating sensor actuator having a deactivated position and an activated position. The sensor actuator engages the second sensor fiber upon the unauthorized movement of the entrance gate causing the sensor actuator to move to the activated position and the fault signal to be generated.

In another aspect of the invention, a method of preventing an unauthorized entry through an entrance into a secured area comprises providing an optical fiber sensor line laced through a plurality of structural elements forming a barrier closing the entrance, and reinforcing the tubular elements with a solid metal rod that delays cut through of the tubular elements until after the sensor line is cut and a fault signal generated. The method includes generating real-time scan signals in the fiber sensor line representing the current state of the fiber sensor line; processing the scan signal to establish a baseline signal from the sensor line representing an undisturbed state of the optical fiber sensor line; and comparing the scan signals to the baseline signal. A fault signal is generated in response to receiving a scan signal having a predetermined deviation from the baseline signal. The method includes processing the fault signal to establish a nature and location of a fault condition occurring in the barrier at the entrance using a stored set of computer readable signature fault conditions; and alerting personnel of the fault condition.

DESCRIPTION OF A PREFERRED EMBODIMENT

The present invention is now described more fully herein with reference to the drawings in which the preferred embodiment of the invention is shown. This invention may, however, embody other forms and should not be construed as limited to the embodiment set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art.

The detailed description of some of the components that follow may be presented in terms of steps of methods or in program procedures executed on a computer or network of computers. These procedural descriptions are representations used by those skilled in the art to most effectively convey the substance of their work to others skilled in the art. These procedures herein described are generally a self-consistent sequence of steps leading to a desired result. These steps require physical manipulations of physical quantities such as electrical or optical signals capable of being stored, transferred, combined, compared, or otherwise manipulated. A computer readable medium can be included that is designed to perform a specific task or tasks. Actual computer or executable code or computer readable code may not be contained within one file or one storage medium but may span several computers or storage mediums. The terms “computer,” “processor,” and “server” may be hardware, software, or combination of hardware and software that provides the functionality described herein, and may be used interchangeably.

Certain aspects of the present invention are described with reference to flowchart illustrations of methods, apparatus (“systems”), or computer program products according to the invention. It will be understood that each block of a flowchart illustration may be implemented by a set of computer readable instructions or code. These computer readable instructions may be loaded onto a general purpose computer, special purpose computer, or other programmable data processor or processing apparatus to produce a machine such that the instructions will execute on a computer or other data processing apparatus to create a means for implementing the functions specified in the flowchart block or blocks. Accordingly, elements of the flowchart support combinations of means for performing the special functions, combination of steps for performing the specified functions and program instruction means for performing the specified functions. It will be understood that each block of the flowchart illustrations can be implemented by special purpose hardware based computer systems that perform the specified functions, or steps, or combinations of special purpose hardware or computer instructions.

Referring now to the drawings, the invention will now be described in more detail. As can best be seen inFIGS. 1 and 2, an entrance security system, designated generally as A, is schematically illustrated. The security system includes a barrier assembly component, designated generally as B, serving to prevent passage through an entrance of a secured area; and a security interface component, designated generally as C. Barrier assembly B prevents passage of a vehicle, individual, or other object, and generates a fault signal if attempt is made to compromise the barrier closing an entrance14into a secured area. The illustrated embodiment, barrier component includes a removable gate10closing an entrance into a secured area. The gate includes a plurality of elongated, hollow structural elements11arranged in an intersecting pattern forming a triangular gate. The gate structure includes a horizontal element11a, an intersecting element11b, a base element11c, and an intermediate element11d. It is to be understood, of course, that the barrier component may be a movable gate, a fixed barrier, or any other barrier structure closing an entrance, and may be formed in a grid pattern of parallel cross elements, a pattern of interesting or inclined elements, and other arrangements servicing as a barricade to entrance of a secured area. For the purpose that will become apparent hereinafter, structural elements11include hollow cores13.

A fiber optic sensor line12is laced through the hollow cores of hollow elements11forming the barrier component, as illustrated inFIG. 1. The fiber optic sensor line enters the gate from the ‘left’ side. It enters the structure of the gate and is ‘laced’ through each structural11a-11dcomponent of the gate assembly. Any attempt to cut the center of the gate, or a supporting pivot post104will result in a cutting of the fiber. The sensor line is connected to a scanning unit18on one end and to a terminal device15on its terminal end. The terminal end of the cable need not be physically or electrically connected to the OTDR. The scanning unit scans the sensor line and receives back a scan signal40. Any suitable scanning unit, such as an optical time domain reflectometer (OTDR) may be used.

A sensor unit E is secured to the top of gate post104for sensing the opening of gate10in a manner to be described in more detail hereinafter. Sensor unit E includes an optical fiber sensor line16connected to an OTDR19. A line scan signal41is output from OTDR19representing the current condition of sensor line16.

In the illustrated embodiment, security interface component C processes scan signals40,41for detecting a prescribed signal attenuation and for determining the nature of an intrusion attempt and identifies the barrier and entrance involved. Fiber optic cable12is used to sense opening of the barrier gate. Line scan signal40is received by the security interface system and processed to determine if an unauthorized gate movement has occurred. Fiber sensor line16is used to detect an attempt to sever, or severance, of a structural element11in barrier B. Line scan signal41is processed according to established signal characteristics to determine a break or attempted break in the line. Thus, the product provides the capability to monitor a gate at a remote entrance and provide a status (open or closed) and an assessment of any attempt to open the gate, or cut the gate intermediate its ends.

As can best be seen inFIG. 2, security interface component C includes a computer26having a computer program28containing a set of operating instructions embodied in a computer readable code residing in a memory30of the computer. The computer is connected to a display32or other communicating device for communicating the occurrence of a fault signal42to an operator of the system.

In the event the line is severed, or the gate is impacted, a fault signal42will be generated. As used herein, “fault condition” means a condition in which a structural element11of gate10has been cut or broken through by a vehicle, or individual, and/or encountered material damage, as distinguished from accidental damage. Fault condition also means an unauthorized opening of the barrier gate to a prescribed open position. While the security system is illustrated as combining the OTDR system18,19, other applications may only require one. For example,FIG. 4illustrates barrier component B in the form of a fixed barrier34closing an entrance to a culvert leading to a secured area. The grate barrier includes a series of parallel structural elements11laced with one or more sensor lines12connected to individual scanning units.FIG. 5illustrates barrier component B in the form of a gate36(moveable), or a grate barrier (fixed), having structural elements11arranged in an intersection grid pattern with one or more sensor lines12laced through the grid. The gate or grate barrier closes an entrance through walls or fencing38. For example, if the barrier is a fixed grate that is generally unmovable, only system18may be needed.

The interface security system is computerized and initially must establish a base line signal D for the scan signals40coming from the laced gate sensor line12, and a separate base line signal D for scan signals41coming from the sensor unit E. Since the procedure for establishing the base line scan signal is the same, only the procedure for establishing the base line signal for laced sensor line12will now be described. It being understood that the procedure for establishing the base line for scan signals41is the same.

OTDR18continuously scans the optical sensor line within gate assembly B and communicates scan signals40in the line to security interface component C, as will be explained more fully below. Computer26is programmed to compare the scan signals to a baseline signal D to determine whether predetermined signal deviation representing a fault condition has occurred. In the event the fault condition is detected, fault signal42is generated by the interface component along with a computation of the type of fault and location of the fault condition at entrance12. For example, display32may include a map of the area depicting the location of the entrance and fault condition on the map.

Conventional input devices, such as a keyboard or mouse, may be provided for operating computer26. Other means of displaying the OTDR signal may also be used.

Computer26continuously monitors scan signals40produced by OTDR18when scanning the fiber optic cable. When the computer is first turned on, the computer acquires baseline signal D from the OTDR, as can best be seen inFIG. 6. The baseline represents the status of the fiber optic cable being monitored at a normal, undisturbed state. For example, while initially scanning the line the scan signal will likely include some noise attenuations at44, followed by a launch signal46in the scan. A launch is created by a significant attenuation or spike in the scan to a normalized level. The normalized level at48is the beginning of baseline signal D. The system continues to read the baseline until a drop occurs at50. The drop indicates the end of sensor line12being scanned. After the drop, noise44again will be recorded by the OTDR. The computer system will then ignore small peaks52aand52bat the beginning and at the end of the baseline signal which is merely reflections of the launch and the drop. Baseline signal D established for the security application being made will be compared to all future scans of the fiber optic line to determine if a fault condition has occurred.

During scanning, computer26continuously receives scan signals40representing scans of fiber optic cable12from OTDR18. A cable being monitored will have a characteristic baseline signal depending on the security application being made and security configuration. A straight cable extending perfectly vertical from the OTDR will be one of the few instances that no attenuations will be found in the baseline. As illustrated inFIG. 1, fiber optic sensor line12will likely have seven characteristic bends when laced through the hollow structural elements of barrier gate B. The bends will likely produce seven distinctive attenuations at12athrough12g. Each attenuation represents one of the bends in the lines at the intersections of the structural elements. With each repetitive scan, the computer system compares the scan signal to the baseline signal to see if any signal deviations and attenuations are detected. If a signal deviation is detected, the computer analyzes the deviation signal to determine what type of fault has occurred, as well as the specific location of the fault. If the scan attenuation matches a baseline attenuation, such as at12a-12g, the computer system will not recognize a fault condition.

Thus, every attenuation detected by the computer system will not indicate a fault and may simply indicate a pre-existing bend attenuation. Further, some signal attenuations will be slight, indicating a slight movement of the cable that does not indicate a fault. The signal deviations that most concern a user of this system will be those that show a significant fault. The location of the attenuation on the signal will correspond to a location on the fiber optic cable where a fault may have occurred.

As can best be seen inFIG. 7, in the event that a fault condition50is created in gate10, fault signal42occurs in scan signal40. Computer analysis involving a comparison of baseline signal D and fault signal42indicates an abrupt deviation in attenuation sufficient to create a fault signal. Computer26generates a fault signal which is delivered to display32in the form of a map or other information indicating the location of the fault condition which may be looked up in a computerized table. For example, an attenuation of −62 DB may represent a complete break in the optical fiber sensor line12and hence the barrier gate or grate. This information may be stored, as predetermined or signature fault signals, in a table format allowing for quick retrieval by computer readable instructions. A fault condition distance of 2,100 meters may be the location of an entrance gate to the secured area according to the location lookup table. A computer generated map may be quickly displayed at32. Various ways of responding to the fault condition may be had at that time. For example, law enforcement personnel may be dispatched immediately to the location, various alarms may be activated, and other means of communicating the fault condition in a manner dictated by the security application being made.

Computer program28includes instructions for communicating with OTDR18and receiving repetitive scan signals, and analyses instructions for comparing the scan signals to the baseline signal which has been established. The instructions include lookup instructions for looking up the location of a fault signal in the event the analysis instructions determine a deviation from the baseline signal representing a signature fault condition. The lookup instructions look to see if the deviation matches the level of deviation required to indicate a complete break of the sensor line, material damage to the line, and/or other conditions in the line which amount to a fault condition. The computer program may also include a map of the secured area and instructions to look up the location of the fault condition in response to the distance measured by the OTDR. Display instructions may include instructions for displaying the map and the location on display32. Alarm instructions can be used to alert the attendant to the map display and the fault signal generally.

Referring now toFIGS. 8 and 9, flowcharts detailing the computerized operation of the security system are shown.FIG. 8shows the initialization process of determining baseline D from scan signal40associated with barricade cable10in the security system. At step60, the system initially scans fiber optic sensor line12, extending through barricade cable10. At step62, the system error checks the information coming from the fiber optic line or cable. For example, a user may input parameters indicating the length of the cable to be scanned. If the length scanned by the system is greater or less than this parameter length, then the system will return an error and rescan the line from the start to ensure a proper-base line is detected. Other parameters such as attenuations that should be found in the line may also be entered to assist in error checking. If a launch signal46is detected at step64, the system will begin acquiring and storing baseline signal D in computer memory30at step46. If the attenuation is not considered a launch signal, the system will continue to scan fiber optic line12until it detects a launch attenuation. The launch signal occurs when a significant rise from the noise floor occurs in the reading of the signal from the OTDR. Any insignificant attenuations simply indicate noise44and do not show the beginning or the end of the baseline signal.

Once the system has acquired a launch and begun measuring the baseline at step66, it will continue to do until it detects a drop signal50at step68. The drop signal is the inverse of the launch signal indicating the end of the baseline signal. The drop signal returns the scan signal of the fiber optic line to noise44. At this point, the system will end acquiring the baseline at step70. At step72the computer analysis adjusts the baseline signal for reflection. There is a distance immediately following the launch and immediately preceding the drop that is not a measurement of the baseline but rather a reflection signal at52aand52boccurring at the beginning and end of the line. This reflection is not be considered element of baseline signal D, therefore, it is removed from the baseline signal at step72. At step74, the actual baseline is stored by the system in computer memory for comparison to future scan signals. The baseline is necessary in order to make all comparisons to future scans to determine a fault condition is occurring in the braided security cable of the barricade component.

FIG. 9shows an overview of the normal operation of the security system while scanning the sensor line. After establishing the baseline signal, the scanning of the line will take place at step78. The system will determine if any reflections, spikes or attenuation deviation from the baseline is detected at step80while scanning the sensor line. If no deviation from the baseline has taken place, the system will return to step78and continue to scan the line for an reflection deviations. Attenuation deviations do not necessarily have to indicate a fault. Sometimes attenuations will indicate the crimping or some other bend in the sensor cable. If these existed at the time of the determination of the baseline, then no action is taken if the attenuation found matches this baseline attenuation. If the attenuation does not match the attenuations in the baseline signal, the system will look up the deviation level from a data set stored in computer readable code, and determine if a fault signal condition exists. If so, the computer will generate a fault signal at86. The fault signal can comprise multiple indicators. For example, an audible indication may be given to the user of the system indicating a fault. In a further embodiment, a visual indication may be given to the user indicating the location of the fault. In a further embodiment, the visual display may comprise a map with an indication at the point on the map where the fault has taken place.

Referring toFIGS. 10-11, an embodiment of a barrier gate opening sensor in the form of a sensor unit E will now be described in more detail. The invention provides monitoring of vehicle or pedestrian gates on entrances in perimeter fencing or walls, barriers and gates on other entrances leading to a secured area, and between areas of varying security within a facility. There are two principle methods to breach an entrance barrier or gate; (1) opening the gate with a key, or by cutting the chain or locking device, or (2) cutting through one or more structural elements forming a element of the gate between the ends of the gate assembly, as described above. The invention provides a capability to detect either of these methods to breach a gate. When coupled with the software, both the nature of the breach and the exact gate involved can be ascertained from a remote monitoring location.

The opening and closing of gate10of gate assembly B is monitored by means of sensor unit E mounted on pivot post104supporting the gate components. This arrangement is illustrated inFIGS. 10 and 11. Sensor unit E includes a protective housing105mounted atop the pivot post of the gate assembly. Inside the housing is fiber optic cable sensor switch108having a reciprocating switch actuator108a, and a cam in the form of a cam plate110. As the gate opens or closes, the cam plate is turned. The sensor is ‘tripped’ when the cam plate is rotated from a closed position (FIG. 10) to an open position (FIG. 11).

As can best be seen inFIG. 10, cam plate110and sensor switch108are shown in the ‘gate closed’ position. The cam plate is attached to structural element11cwhich serves to rotate on pivot post104of the gate assembly and rotates with element11cas the gate is moved. A cam follower110ais mounted to sensor actuator108which presses against optical sensor fiber line16when the cam rotates. When the gate is closed, the fiber sensor line rests in a normal loop116within the sensor.

In the illustrated embodiment, switch actuator108ais slidably received in a housing block108b. Sensor line16received in a cradle108chaving opposed contact surfaces between which the sensor like is received. In the closed position, the cam follower is urged into cam plate detent110bby a spring111.

As illustrated inFIG. 11, gate100has been opened. Now, cam plate110has rotated 90 degrees from the ‘gate closed’ position. Cam follower110amoves inwardly causing switch actuator108ato move so that a characteristic bend118is formed in the fiber. The computer processor detects this bend and recognizes it as a gate opening. The software28recognizes the specific entrance where the unlawful activity is occurring. Once gate10is opened and the fiber bent, opening the gate further will not change the signal produced by the fiber because the constant surface provided by the cam maintains a constant pressure by cam follower110aon the fiber16. When the gate is returned to its closed position, the sensor switch is returned to the gate closed position (FIG. 10). When the cam follower110areturns to detent110bin cam plate110, pressure is no longer exerted on the optical fiber.

Referring toFIGS. 12 through 21, alternate embodiments of a grate barrier for different applications are illustrated. As can best be seen inFIGS. 12 through 15A, a grate barrier, designated generally as G, is illustrated having the particular advantages of detecting an attempted removal or cut through of the barrier, but delaying the completion of a severance a sufficient period of time to allow guard personnel to reach the culvert first. The assembly includes a grate barrier120and a mounting frame122. The barrier is constructed as a grid of tubular steel structural elements124and126spaced on 6″ centers and laced with single mode optical fiber154,156. While a single optical fiber can be used in certain applications and monitoring systems, in the preferred embodiment, two fibers154,156are used in a “double end” monitoring system. Preferably, the fibers are wrapped in a cable wrap157. It being understood, of course, that cable157can denote one or two optical fibers.

The horizontal tubular elements124and the vertical tubular elements126lie in two different planes, and are affixed in a barrier frame128. In one example, the inside diameter of the tubular elements is 0.75 inches and the wall thickness is 0.062. The grate barrier is mounted in a mounting frame122. The size and wall thickness of the frame are typically 1 inch by 2 inches and 0.084 inches respectively. This provides a robust grate assembly that is immune to false alarms due to wildlife, environmental forces, and causal human activity in the area. No electrical power is required at the grate barrier. The grate barrier may be located up to 25 km from the monitoring station.

As an important security measure, a plurality of longitudinal structural reinforcing members128are enclosed in the tubular elements124and126. These reinforcing members delay barrier breakthrough after the sensor line is severed to allow sufficient time for guard personnel to arrive at the scene. Preferably, the reinforcing members are stainless steel rods encased in each vertical and horizontal tubular element having a diameter of 0.50 inches. The stainless steel rods provide additional delay even if the intruder is using a torch. Most of the delay will be after the fiber is broken by the cutting action. This gives responders extra time between the alarm and the intruder penetrating the secured area. The horizontal and vertical tubular elements are welded together at each crossover point, and lie in different planes. This reduces the number of right angle turns the fiber makes and decreases the probability of a false alarm, and also allows for encasement of continuous reinforcing members in both directions.

The grate barrier is installed using mounting frame122affixed to the culvert using tamperproof bolts129. Preferably, the frame includes a “C” shaped channel130frame having three sides130a-130c. The frame is installed, for example, on headwall32of a culvert34to form a frame into which the barrier is lowered. The barrier is contained on the sides and bottom much as a picture is slid into a three-sided frame. Tamper-proof bolts129have two heads. A traditional hex head is used to tighten the bolt during installation. Once the break-away torque is reached, this head will break free leaving only the featureless flat head to secure the installation. Preferably, Torque-LOC bolts available from Woven Electronics of Simpsonville, S.C., are used. Testing of these bolts has shown a delay time of 2 hours per bolt when perfect access is available. The bolts are located behind the barrier, as it sits in the “C” channel, making it impossible to get a tool on the bolts once the barrier is installed.

A service box136is installed on a side of the grate barrier to house fiber optic splices and provide an important security feature. A service loop138of optical fiber for the grate barrier is enclosed in the box. The service loop allows the grate barrier to be removed for required maintenance inside the culvert. To access the culvert, the service box is opened, and the service loop is extended to provide sufficient slack in the optical fiber to allow the removal of the barrier. The box also includes a splice board140for splicing the incoming sensor line(s) with the outgoing sensor line(s). Preferably the service box is alarmed with a tamper detecting, optical intrusion sensor142such as a Tamper-Guard optical sensor available from Woven Electronics of Simpsonville, S.C. The small, simple sensor is mounted inside, adjacent to a door136aof the service box in such a manner that any attempt to open the box will trip the sensor and the monitoring system, as will be more fully described at a later point.

FIG. 15illustrates an alternate arrangement for securing barrier grate120over the culvert opening of culvert134. In this embodiment, mounting plates144are attached over the open end of the three-sided C channel frame122and are attached to the hex head bolts143secured into the concrete headwall136of the culvert. Sensor line157is routed through openings in the hex heads of the bolts143, as well as grate barrier120. In this manner, the sensor line must be severed in order to remove the bolt. In addition, it is highly likely that the sensor line will be significantly bent in trying to remove the bolts so that a fault signal will be produced by the computer interface system either way.

An alternate embodiment of a grate barrier assembly, designated generally as H, is illustrated inFIGS. 16-17which is used where there is no headwall to mount the barrier, and a potential for tunneling down through the sidewall of the pipe exists. In this case grate barrier assembly H may be provided with both “end” and “side” detection capability. As can best be seen inFIGS. 16A,16B, a circular grate barrier146is illustrated having a grid of tubular elements124,126framed by a circular tubular frame147attached at the entrance end of the culvert.

FIGS. 17A,17B illustrate a cage barrier148installed inside a culvert147. It is pushed up the pipe to a point where a “dig in from the side” risk is mitigated. The barrier also includes tubular elements124,126around the perimeter of the barrier. The tubular elements are laced with fiber optic sensor lines to detect side dig-in intrusion attempts. It has been found that placing the cage barrier in the culvert at a point about 24 inches below the ground surface is effective for preventing dig-in intrusions. In the case of the entrance barrier or the cage barrier, the barrier is secured inside the pipe with tamper-proof bolts129to prevent removal. The bolts may be secured using any suitable concrete fasteners129adrilled into the concrete for receiving the bolts. Removal from the pipe is also prevented by controlling the slack in the optical fiber. The slack is secured on the protected side of the barrier via a service box136as with a flat barrier. Any attempt to pull the barrier out of the pipe will put a strain in the fiber and will be detected. Grate barriers146,148may be used alone, or in combination.

Thus, it can be seen that robust grate barriers are provided at each location manufactured of steel tubing, reinforced with steel rods, and laced with optical fiber to detect tampering. Either control of the service loop with a tamper sensor42protecting the service loop, or security bolts laced with sensor lines prevents removal of the barrier.

Referring now toFIGS. 18-21, a preferred and alternate monitor for monitoring the optical fiber sensor line and detecting a fault condition representing an unauthorized intrusion attempt will now be described.

As can best be seen inFIGS. 18A, B, a double-end optical fiber sensor line system monitor, designated generally as A′, is illustrated for detecting intrusions and ensuring that a complete break in the fiber will not render the system inoperative. As illustrated, the system includes a pair of sensor line scanning units in the form of a primary OTDR150and a secondary OTDR152optically connected to first and second optical fiber sensor lines154and156, respectively. Sensor line154is operatively terminated at one end to the OTDR150and is connected in a non-terminated manner at OTDR152. Likewise, sensor line156is operatively terminated at OTDR152and is connected in a non-terminated manner to OTDR150. Other scanning arrangements and means may be provided such as a single unit combining the pulsing and scanning functions of two units, illustrated schematically inFIG. 20C. Both sensor lines are routed through either grate barrier120,146,148, and sensor142or143, and may be enclosed in cable wrap157. However, as mentioned previously, the term sensor line may connote one or two optical sensing fibers, wrapped or unwrapped, unless specified differently, as herein. Primary OTDR150and sensor line154are connected to a system server/computer or processor160by means of a cable162, and secondary OTDR152and sensor line156are connected to the computer by a cable164. A computer monitor166is connected to the server by means of a cable168. Optionally, a remote computer170may be connected to the server by means of the internet or other network. In the illustrated embodiments, door opening, intrusion sensor142(FIG. 18A) or a plurality of hex bolt intrusion sensors143laced with the sensor lines (FIG. 18B) are illustrated in series with a grate barrier120,146, or148. In this case, a boil154aof sensor fiber154, and a coil156aof sensor fiber156are provided between the barrier and sensor to provide optical separation. This optical separation allows the computer logic to differentiate between signals from the barrier and the sensors. The sensor lines may be routed through any number of barriers and intrusion sensors in a “daisy chain” arrangement as needed to secure a perimeter.

Primary sensor line154may be considered the primary line and normally senses an intrusion attempt by opening of service box door136band/or removal of a hex bolt143. However, should the sensor line be cut and a complete break of the line occur, the sensor line152will continue to sense intrusions on a first, upstream side of the break, and sensor line154will continue to sense movement of covers on a second downstream side of the break.

In operation, the primary OTDR emits a light pulse signal every 10 seconds, for example, and this pulse travels down the optical fiber sensor line154. The light travels to the end of sensor line154at the secondary OTDR and reflects back to the primary OTDR. As long as the reflections and attenuations match the reflection signal created when the system was installed, the OTDR waits till the appointed time and repeats the process. Should the emitted light encounter an obstacle, a reflection is “bounced” back to the OTDR that does not match the reflection seen when the system was installed. Should light be lost (attenuated) from the fiber, this reflection occurs at a lower energy level, than was originally transmitted. This combination of reflections and attenuations defines a picture of the fiber sensor line, and this picture is called a signature. As long as the signature matches that of the original configuration of the system as established in the baseline signal, the software records the data and takes no action. The baseline signal is established as described in reference to computer interface system C. Illustrated inFIG. 19Ais an OTDR trace showing attenuation in the light energy at a location that corresponds to the location of a service box136being monitored by the system. The door of the box has now been opened. We know that because the attenuation “dip” on the graph at180is the signature of an open door, or signature bend caused elsewhere in the systems. The system computer logic can differentiate these bends. A vertical spike in the graph at182is a reflection that indicates the end of the fiber. All light is reflected from the cleaved face of the fiber, thus the high reflective spike, indicating severance of the fiber.

The secondary OTDR fiber154is shown as black in the image to signify that the fiber is dark and not normally in use. Normally, secondary OTDR152and sensor line156are only used when there is a complete break in the sensor lines, as explained below. Preferably, the primary OTDR and the secondary OTDR are cycled by the processor every 24 hours so that the secondary OTDR and sensor line are dark for 24 hours and then the primary OTDR and sensor line are dark for 24 hours to ensure that both units remain in operational. Of course, while one unit is dark the other is operational with light pulse signals. While both units could be operated at the same time, it would serve no purpose.

Severance of the sensor line is known because spike182has “moved” on the graph from right to left at184. When the software sees this signature of a break (a reflective spike) several things happen. Among these triggered events is the firing of the secondary OTDR152to pulse secondary sensor line156. The secondary OTDR monitors secondary sensor line156housed in the same cable as primary sensor line152of the primary OTDR. The secondary OTDR can monitor the intrusion downstream from the break and the primary OTDR monitors those upstream from the break. This “double end” arrangement ensures that a break or severance in the fiber will not render the system inoperative. In similar fashion, the secondary OTDR will be fired if the primary OTDR fails and the system will remain operable. The signature intrusion signals are stored in computer readable code in the intrusion level data set for comparison to the periodic reflected pulse signals. The double-end system is described in more detail in U.S. non-provisional application Ser. No. 11/890,450, filed Aug. 6, 2007, entitled “Double-End Fiber Optic Security System For Sensing Intrusions, incorporated fully herein by reference.

The OTDR technology and software identifies every barrier and intrusion sensor, and its location, by its optical distance from the OTDR and monitor every meter of fiber anywhere in the system-fiber in the grate barriers, fiber in the tamper and intrusion sensors, fiber running out to the barriers, and fiber running between the barriers, and their locations. Damage anywhere in the system is detected and its location determined. In this system, multiple barriers and intrusion sensors can be “daisy chained” together on two pair of OTDRs. Two fibers would be laced through the barriers and sensors—one ODTR connected to each. This configuration provides complete redundancy to the system because no single point of failure exists. Additionally, the system provides map based graphic user interface and GPS location capability, fully adjustable breech and break alarms, email and pager alerts, remote PC visibility of the system's status, alerts, and complete event logging on the system.

A computer interface system C′ for the double-end monitoring system includes a computer or processor160, a resident computer program (software)161having features to process the detection and assessment of a pulse reflection and intrusion signal to determine the cause of the signal and select a response to the threat automatically. For example, in the case of the signature bend signal attenuation such as an open door shown inFIG. 19Athe software can trigger a camera to see the specific reason that the manhole is being opened. This image will be captured and transmitted over the network to interested parties as a customer configured response to the assessment. In the second signature signal shown inFIG. 19Bthe cutting of an optical sensor line signifies a high priority threat at the location. In this case, the software may advise a response team of the status and location of the cut. This response can include initiating a “lock down” of all perimeter gates in response to the signature, and alerting off-site response teams as back-ups. Any number of sensors, signature signals, and responses may be programmed depending on the application being made. Assessment of the intrusion and initiating responses is a unique aspect of the present invention. The signature signals are stored in signature data set163in computer readable form and, for example, in a table look-up form. The data is stored in a computer memory accessible by the processor, and may also include response data used to signal a predetermined response to the proper personnel, a desired by the customer/user. The data is compiled by performing bending or damage to the fiber lines that would occur under prescribed intrusion attempts desired to be monitored and capturing the signature of the reflected pulse signal. The software tools match a reflected pulse signal deviation with one of the signature intrusion levels signals in the data set, a proper response to a change in a sensor line signal can be delivered. A suitable computerized system and program is disclosed in U.S. non-provisional application Ser. No. 11/083,038, filed Mar. 17, 2005, entitled “Apparatus And Method For A Computerized Fiber Optic Security System,” now published as International Publication Number WO 2006/05277 A2, on May 18, 2006, commonly owned and incorporated by reference into this application. The system recognizes the different signature signals received from the OTDR on the basis of predetermined rules, and interprets the real event that caused the signal. The system also allows the use of multiple sensors to be recognized simultaneously by the system and unique baselines to be identified by sensor type, location, etc. The system can discern the difference between authorized and unauthorized activity. The programmed processor has the ability to catalog predetermined events on the basis of the reflected signals and recognize them as either authorized or not authorized when (and where) they occur.

Referring now toFIGS. 20A through 20D, alternate embodiments of system monitors are illustrated and will now be described.

As can best be seen inFIG. 20A, a system, designated generally as I, is illustrated having a monitoring unit190connected to a grate barrier120,146, or148. This is a simplified system, monitoring only a barrier and/or other sensor. Monitoring unit190is provided for monitoring the fiber or sensors while detecting events above a preset threshold within a second. The monitor unit can differentiate between a triggered sensor event and a fiber break event, or fault condition. The monitor evaluates a monitored signal relative to its particular secure state. This secure state, called a baseline, may be easily taken and saved by the user. For this purpose, the monitoring unit includes a laser192that transmits a line along an optical fiber sensor line154which is received by a power meter194that senses the light received after passing through the lacings of the grate barrier and barrier removal sensors143(or142).

FIG. 20Billustrates a system monitored, designated generally as J, which includes a separate optical monitoring units190. The first unit190is connected to the grate barrier, and the second unit190is connected to the sensor line running through the intrusion sensor bolts143(or sensor142). This provides two separate systems for monitoring the barrier cut through and removal. This embodiment may be advantageous in certain applications where it is desired to have separate system monitors.

Referring toFIG. 20C, a system monitor, designated generally as K, is illustrated which utilizes a single OTDR150to monitor a grate barrier and intrusion sensor bolts143(or sensor142). This single end system is desirable in some applications as opposed to the double-end system described previously.

FIG. 20Dillustrates yet another alternate embodiment of a system monitor, designated generally as L, where two separate OTDR systems are utilized to monitor first the barrier grate cut through, and secondly an attempted removal of the barrier either by intrusion sensor bolt removal or opening of the service box (sensor142).

Any suitable monitoring unit190may be utilized in the above monitoring system such as a Light-LOC Express module unit available from Woven Electronics of Simpsonville, S.C.

Referring now toFIGS. 21A,21B, an embodiment of a fiber optic intrusion sensor142is illustrated which includes a housing202having a fiber entrance204and a fiber exit206. A moveable carrier, designated generally as208, is illustrated which includes a lower strap208a, an upper strap208b, secured together by means of a sensor block210. Sensor block210includes a lower adjustable abutment210aand upper abutment210bwhich produce the natural and characteristic bends in the sensor fiber. The slidable carrier208moves between a normal deactivated position shown inFIG. 21Ain which the carrier is raised by magnetic attraction between magnet209and the removable member (box lid136a) to its upper most position. InFIG. 21B, the carrier is shown in its downward activated position caused by interruption of the magnetic attraction between magnet209and the removable member.

In order that a quick opening and closing of the removable member results in a discernable signal that can be detected by the processor, e.g. OTDR12, a signal control device is provided to shape the signal so that any signal generated by the sensor has a prescribed minimum pulse duration (width), regardless how quickly the manhole cover is removed and replaced. In the illustrated embodiment this is accomplished by a delay mechanism, designated generally as211, in the form of a fluid cylinder218that delays the movement of carrier108to the deactivated (uppermost) position following movement to the activated (downward) position. Thus, the deflection of the fiber optic back to its natural state is delayed. In the illustrated embodiment, means for delaying return of the fiber optic to its natural shape so that a pulse width of sufficient duration for sampling is generated under the control or shaping provided by delay hydraulic cylinder218. The signal control device produces a signal having a prescribed minimum pulse width that has been determined to be reliably recognizable by the processor. For example, a minimum pulse width of 15 seconds is necessary for recognition and sampling by a typical OTDR. To ensure reliable detection, the control device is preferably set to produce a minimum pulse duration of 45 seconds. Thus, even if the intruder drops the cover quickly, for example after seeing the sensor, a recognizable signal is transmitted to the processor.

Delay cylinder218includes a piston head224at the end of piston rod220having a check ring224a. A compression spring226is carried between piston head224and an upper end of a fluid chamber228in which oil, or other hydraulic fluid or gas, is enclosed. Delay cylinder218is positioned between an abutment240affixed in housing202and bottom strap208ato act as a shock absorber to delay the return of carrier208to its deactivated position. A suitable cylinder218is manufactured by Enidine Incorporated of Orchard Park, N.Y.

In operation, in the normal position of sensor142, slidable carrier28is in its up position which urges piston20upwards into cylinder compressing spring226When the magnetic attraction is broken by sufficient movement of the manhole cover, piston head24moves downward quickly as the spring decompresses. In this situation, fluid either bypasses check ring24a, or exits a major port22so that sensor fiber14ais deflected quickly to form its characteristic bend233producing a signal. In order that the pulse width of the signal is sufficient to detect, even if the cover is placed back quickly, the ascent of the carrier is retarded. This is caused by the fact that in order to reach its normal shape in the normal position of magnet209, fluid pressure must be overcome, as well as the compression of spring226. Thus, as carrier208moves upward causing piston rod220to move upward, piston head224is caused to force fluid out through the restricted, minor orifices230into passage234, as well as to compress spring226. This delays the termination of the signal sufficiently so a pulse width is provided that can be detected by the OTDR. This is particularly advantageous if a large number of sensors are utilized along a fiber network having a long distance so that activation of a plurality of sensors can be detected generally concurrently even if the closure member is quickly replaced. Sensor142, and system therefore, is described in more detail in U.S. non-provisional application Ser. No. 10/429,602, filed May 5, 2003, entitled “Fiber Optic Security System For Sensing Intrusion Of Secured Locations;” and PCT application no. PCT/US2004/013494, filed May 3, 2004, entitled “Fiber Optic Security System For Sensing The Introduction Of Secured Locations;” incorporated fully into this application by reference.

Thus, it can be seen that a highly advantageous construction for a security system and intrusion sensors can be had according to the invention where fiber networks can be utilized to provide optical fiber sensor lines routed through barriers and/or sensors connected in series and terminated with an OTDR device to determine the occurrence and location of an intrusion anywhere along the fiber optic lines. In this manner, the entire network may be secured against terrorists or other acts of invasion, vandalism, etc. The fiber optic monitoring system maintains the ability to recognize specific signals on a common fiber(s) and segregate those that are authorized from the signals that denote unauthorized activity. Currently, the invention can recognize at least nine different signals on the fiber. These signals may occur on the same fiber, or separate fibers. As illustrated, the system may function with both contact and non-contact sensors. The software instructions can uniquely detect intrusion with both contact and non-contact sensors simultaneously. In either case, the intrusion detection is accomplished by interrogating the light reflected out of the fiber when a sensor is triggered. The system provides for multiple sensors to be “tripped” at the same time and the invention will track the status of each independently.

While a preferred embodiment of the invention has been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without delaminating from the spirit or scope of the following claims.