WO1994018649A1 - Optic fiber security system - Google Patents

Abstract

The integrity of a barrier such as a fence or a vault wall may be monitored by threading optic fibers into the barrier. A light signal is sent into the fibers and is monitored at the other ends. The monitoring circuit comprises parallel connected first means (U1B) for comparing the received signal directly with a first reference voltage and second means (U1C) for comparing the received signal, after integrating (U1D), with a second reference voltage. The monitoring circuit includes a Potentiometer (P1) for sensitivity adjustment of the integrated signal.

Description

Optic Fiber Security System

BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates to security systems employing fiber optic cables. More particularly, this invention relates to fiber optic security systems employed for monitoring chain link or other fence perimeters, buildings, and objects to detect intrusion of the perimeter fence or building or theft of the object. Description of the Background Art

Presently, there exists many types of security systems designed to monitor perimeters of land, buildings and enclosures containing valuable objects, and even the objects themselves, from unauthorized intrusion and theft. Upon detection of such an authorized intrusion or theft, most security systems actuate an audible alarm to scare awa the intruder or thief. More elaborate security systems include silent alarms wherein the local law enforcement agency or a commercial security service is automatically notified via telephone that an intrusion and/or theft has taken place. Still other security systems include video cameras which are actuated when an intrusion or theft is detected to videotape the intruder or thief. See, for example, U.S. Patent 5,144,661.

Most security systems employ a plurality of metal conductor wires which are formed in a plurality of closed loops, often called security zones. The closed loop of each zone is strategically xnstalled for each application. For example, when securing the perimeter of land bound by a chain link fence, the wire may be threaded through the links of the chain about the entire perimeter. Similarly, the wire may be installed about windows and doors, with serially connected switches positioned at each window or door to open the closed loop of wire when the window or door is opened. In the case of securing an object, the wire is threaded through a portion of the object (e.g. through the vent holes on the chassis of a computer) .

In each application, the security system monitors the continuity of each closed loop of wire and determines that an intrusion or theft has occurred when such continuity is broken. In most systems, the continuity of each loop is monitored by applying a voltage at the beginning of the loop and measuring the voltage at the end of the loop such that the voltage drops to zero when a discontinuity is created in the loop indicative of an intrusion or theft.

Unfortunately, security systems employing metal conductor wires are susceptible of being bypassed by the intruder or thief by simply connecting another wire in parallel with a segment of wire thereby forming a bypass around that segment in the looped wire. The bypassed segment of wire may then be cut out of the loop since the bypass preserves the continuity of the loop. Intrusion and/or theft is therefore possible.

More sophisticated security systems have been developed which attempt to detect any bridging or bypassing of any segment of the loop; however, such systems are more perceptible to false alarms due to fluctuations in the voltage which could occur from outside sources such as electromagnetic interference.

More recently, some security systems have employed fiber optics cables rather than metal wires to form each loop. In the simplest systems, light from a light emitting diode (LED) or the like is shined into one end of the fiber optic loop and then viewed via a photo-diode or the like at the other end, thereby readily detecting any discontinuities in the loop. Most importantly, no segment of the fiber optic loop can be bypassed since any attempt to splice a bypass into the fiber optic cable will result in at least a temporary blocking of light through the fiber optic loop. U.S. Patent 4,379,289 discloses a typical fiber optic security system.

In addition to the inability of an intruder or thief to bypass a segment of a fiber optic loop, the inherent light characteristics of fiber optics allow the security system to detect when the fiber optic cable is merely bent and not necessarily broken. Specifically, it is well-known that the parameters of light shined through a fiber optic cable change as the fiber optic cable is bent. Thus, fiber optic security systems monitor these parameters to detect such changes that are indicative of a mere bendin of the fiber optic cable constituting the loop. As a result, a significantly more secure system can be achieved. U.S. Patent 4,292,628 discloses one such fiber optic security system.

Fiber optic security systems have been employed in many applications to take advantage of the capability of monitoring a mere bending of the fiber optic cable. For example, patents U.S. 4,777,476, U.S. 4,829,286, U.S. 4,450,434, DE 3928635A1 and DE 3706999A1 disclose security systems wherein fiber optics are incorporated within a chain link fence for perimeter monitoring. In these patents, the fiber optic cables are woven through the links of the chain link fence, through the vertical fence posts of the fence and/or threaded about the barbed wire of the climbing guard at the top of the fence. In each patent, the security system employs appropriate electronics to detect a change in the light parameters which would occur when the fiber optic cable is bent, indicative of an intrusion.

In similar applications, fiber optic security systems have employed fiber optics that are positioned within a wall, such as shown by U.S. Patent 4,371,869 and by fiber optics which are woven within a screen, such as shown in U.S. Patent 5,049,855.

Still further, fiber optic security systems have been employed for securing objects such as computers. See, for example, U.S. Patents 5,003,292 and 5,055,827, the latter of which includes means for detecting attenuation of the light within the fiber optic cable when the cable is bent or broke.

Fiber optic security systems have recently begun to employ elaborate electronics for specific applications. For example, in U.S. Patent 4,591,709, a differential amplifier is employed for monitoring the difference in the light transmitted through a pair of fiber optic cables to detect an intrusion via one of the fiber optic cables relative to the other. U.S. Patent 4,980,913 illustrates a fiber optic security system employing redundancy. Further, U.S. Patents 3,814,841, 4,577,184 and 4,633,235 illustrate even more elaborate monitoring and types of encoding that may be employed in connection with fiber optic security systems.

SUMMARY OF THE INVENTION For the purpose of summarizing this invention, this invention comprises a security and measuring system for a multitude of objects using fiber optics and associated electronics. More particularly, the security system of the invention employs one or more fiber optic cables and associated electronics in such a manner that light transmitted through the fiber optic cable is sensitive to bending of the cable, which sensitivity may be adjusted for different applications.

The fiber optic security system of this invention may be integrated into applications that involve detecting movement or disruption of objects that have been fitted with the security system. The invention may also be employed to measure the amount of movement or the integrity of an object in relation to an original placement or position, in such a manner that any deviation seen as an X-Y function from an axis placed through the center of a fiber optic cable, may be detected, measured and compared with the original position. Further, the invention may be employed in applications such as perimeter security using a chain link or other fence, building security within or on walls of the building, device or artifact security as noted above, mobile perimeter security, structural damage and monitor detector, and structural flexibility movements. In each application, light emitted from a light emitting diode (LED) or other light source with certain wavelength is projected into one end of the fiber optic cable and then measured at the other end of the fiber optic cable by means of a photo-diode or the like. Associated electronics amplify the output from the photo-diode and determine the intensity of the received light when the fiber optic cable is undisturbed. When the cable is disturbed, by bending indicative of an intrusion, the change in intensity is detected. Importantly, the electronics determine if the change in intensity is indicative of an intrusion or simply normal expansion or contraction of the cable.

The fiber optic security system of the subject invention has many advantages. Specifically, the fiber optic cable cannot be manipulated without causing a change in the parameters in the light transmitted through the cable. The fiber optic cable remains unaffected by changes in temperature, rain, snow, ice, wind, and other weather changes. The fiber optic cable is sheathed so as to not emit any light thereby making it virtually undetectable. The sheath also allows the cable to be installed in many applications without damaging the fiber optic cable itself. The fiber optic cable is safe to persons in the environment because only light (as opposed to electrical current) flows through the fiber optic cable. The fiber optic cable is not O

affected by electromagnetic radiation. Finally, the ability to monitor changes in the transmitted versus the received light parameters results in great sensitivity control, thereby precluding any bypassing or other sabotage while minimizing false alarms.

The foregoing has outlined rather broadly the more pertinent and important features of the present invention in order that the detailed description of the invention that follows may be better understood so that the present contribution to the art can be more fully appreciated. Additional features of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings in which:

Figs. 1A and IB are diagrammatic illustrations of fiber optic principles;

Fig. 2 is a schematic diagram of the fiber optic receiver;

Fig. 3 is a system flow chart;

Fig. 4 is a diagrammatic view illustrating the many applications in which the fiber optic security system of the invention may be employed;

Fig. 5 is a side view of the fiber optic security system of the invention employed in a fence security system;

Fig. 6 is a side view of the fiber optic security system of the invention employed in a wall security system;

Figs. 7a and 7b are side views of the fiber optic security system of the invention employed in a sliding gate security system using a tensioning reel;

Figs. 7c and 7d are side views of the fiber optic security system of the invention employed in a sliding gate security system using an armored cable;

Figs. 7e and 7f are side views of the fiber optic security system of the invention employed in a sliding gate 49

security .system using a quick-disconnect;

Fig. 8 is a side view of the fiber opujc security system of the invention employed in a pedestrian gate security system;

Fig. 9 is a perspective view, partially cut away, illustrating the fiber optic security system of the invention employed in a vault security system;

Fig. 10 is a front view of the fiber optic security system of the invention employed in an object security system;

Fig. 11 is a perspective view of the fiber optic security system of the invention employed in a man-portable security system;

Figs. 12a and 12b are side and top views of the fiber optic security system of the invention employed in a ground detection system.

Figs. 13a and 13b are side and top views of the fiber optic security system of the invention employed in a bridge span security system;

Figs. 14a and 14b are side and top views of a fence mounting bracket for securing the fiber optic cable t a fence post at a bend;

Figs. 15a and 15b are top and side views of a fence strain relief for connecting a fiber optic cable to a fence post; Fig. 16 is a block diagram illustrating primary and secondary power supplies;

Fig. 17 is a front view of the emitter/receiver module of the fiber optic security system of the invention;

Fig. 18 is a detailed perspective view, partially cut away, of the fiber optic security system of the invention employed in a vault security system;

Fig. 19 is a front view of the central control unit of the fiber optic security system of the invention;

Fig. 20 is a front view of the signal interface module of the fiber optic security system of the invention;

Figs. 21a and 21b are plan views of a weatherproof quick-disconnector for connecting the ends of fiber optic cables together;

Figs. 22a and 22b are front and rear views of the man-portable security system module;

Figs. 23a and 23b are side and top views of a strain relief for the man-portable security system;

Fig. 24 is a perspective view of a reel for the man-portable security system;

Fig. 25 is a block diagram of the multiplexed system of the fiber optic security system of the invention?

Fig. 26 is a system wiring diagram for the fiber optic security system of the invention;

Figs. 27A-27L are flow diagrams describing the integration of the fiber optic security system of the invention;

Fig. 28 is a perspective view, partially cut-away, of a cladding positioned about a fiber optic cable; and

Figs. 29a and 29b are side and top views of another fence strain relief bracket for connecting a fiber optic cable to a fence post at a bend.

Similar reference characters refer to similar parts throughout the several views of the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in Figs. 1A and IB, the fiber optic security system of the invention preferably employs multi- mode fiber optic cables of a diameter that is substantially not the same as the wavelength of the light to be transmitted through the fiber optic cable. In this arrangement, the fiber optic cable does not function as a wave guide and therefore any bending of the fiber optic cable will result in an attenuation of the light being transmitted therethrough.

Preferably, the light to be transmitted through the fiber optic cable is emitted from a light emitting diode (LED) which generates a beam of light of a specific wavelength as noted above relative to the selected multi- mode fiber optic cable. The light beam is focused onto one end of the fiber optic cable and rigidly connected into position by means of a suitable fiber optic connector. A photocell sensor is connected at the other end of the fiber optic cable and rigidly connected into position by means of another suitable fiber optic connector. Schematic Diagram of Receiver

In Fig. 2, the photocell sensor connected at Jl detects the output signal from the light fiber. It measures the intensity of the light, producing a voltage proportional to the intensity. The circuit operates from the standard DC supply. Regulator U5 converts this supply voltage to a highly stable voltage level. This stable voltage is delivered to all the other active components in the circuit thereby insuring that the power supply will not affect the sensitivity of this circuit. Connector Jl supplies the signal from the optical detector to the circuit. The signa is then supplied to three other components of the circuit: to the differentiation circuit at R25 and C13; to the latch at UIB; and to the sensitivity control at Pi.

The differentiation circuit detects changes in the received signal level. The output of the differentiation circuit is sent to the integrator at UID. The function of the integrator is to remove the very slow signals that occur over time. Only the quick changes will be detected, and these will then trigger the comparator at UIC. The output of the integrator may be attenuated by the sensitivity adjustment at Pi, which comprises a potentiometer attached to the connector at PI. This potentiometer is available to the installer for use in adjusting the sensitivity of the circuit to the deflections in the fiber. The transistor at Q5 then uses the output from comparator UIC and drives the alarm line low when an alarm state exists. Transistor Q5 produces the alarm signa at the alarm output, with a reference at alarm reference. Any time that the sensor detects a very large change in signal level, it will trigger another latch at UI to provide a second signal to the transistor Q5. When the signal from the sensor activates the latch, transistor Q5 will drive the alarm line in the same way as described earlier.

System Flow Chart

As shown in Fig. 3, the security system comprises many components. This flow chart lists the components that can be used to customize one particular system. The main pieces of the system are the central control unit (CCU) , alarm panel, and controlling computer. A personal computer is used to provide the control for the system. This computer connects to the alarm panel. Among the signals that are received by the alarm panel are the alarm signals from the CCU. These are the fiber-optic generated alarm signals which the CCU has collected. The emitter module is powered by the CCU. It sends its signals along the fiber o the fence. The receiver module detects the signals from the fiber. Also received at the alarm panel are tamper switch signals. The alarm panel is used to control several devices. The security lighting can be activated automatically. A camera can also be controlled from the panel. A video recorder can be started and stopped. A siren can be activated. A speaker can be used to provide a audible alarm. A display panel with indicator lights for each zone can also be controlled from the alarm panel.

The controlling computer performs many functions for the security system. It can monitor the alarm lines. It can control the elevators. It can be used to operate th closed circuit television functions. It can display various video images to the operator, to alert them to an alarm condition. It can track the time and attendance of the guard force. It can provide access control to entries and exits in a controlled area. It can generate the timing required for supervising a guard tour. It can operate a modem which allows remote control of the system. It can activate parts of the system on a timed basis, for regular timed output control. It can provide the control for the audio communications for voice messages. The system has a printer that is useful in producing reports. It also has a modem that connects to a remote computer. The remote computer can provide the same operator assisted control fro the remote location. Applications

As shown in Fig. 4, the standard system for fence security includes the electronics and mounting hardware to provide security against low, medium and high security threats. Standard and non-standard fence sizes as well as additional buried lines can be supported. Sabotage proof as well as electromagnetic pulse and electronic counter-measure resistant, the system provides coverage of estate, commercial and government security needs.

The sliding gate and door security (b) , configuration consists of a single enclosure plastic or steel housing the electronics for one line of coverage. Th amount of fiber optic cable and hardware can be determined at the time of installation and depends on the size and security requirements of the application.

The object security (c) allows any form of object to be secured and monitored with the object security system both on interior and exterior applications. Due to the sensitivity setting in the electronics, movement and/or cutting is detected. The fiber optic cable can be spliced with quick disconnects to provide the ability to remove and add objects within the loop without complications. The maximum length of the loop is 300 ft. and can be supplied with custom increments terminated with splices.

The wall security (d) for wall applications modules are mounted in an enclosure providing coverage of up to 300 ft. of wall. The corresponding hardware kit allows for this installation to occur on any wall whether it is brick, concrete block or stucco.

The vault security (e) is recommended for design into the wall of a vault or room. Using conduit as a guide the cable nets the entire vault or room from top to bottom. Any attempt to enter the vault outside of the door be it through explosives or drilling is detected.

The man-portable perimeter security (f) allows temporary configuration in the field when circumstances do not permit permanent perimeter security measures. Applications are military and commercial and can be integrated into existing systems or act in a stand alone mode. The advantages over tension trip wire systems are that it is sabotage proof, it can be re-used and can electronically transmit an alarm signal that can also activate trigger and fuse relays.

The ground detection security (g) comprises a cable that is buried underneath a layer of pebbles within a well drained concrete ditch. The pebbles distribute the weight needed to trigger the sensor cable as an individual or a vehicle passes over. The advantage of the system is that it remains undetected until triggered and provides security against tunneling and the use of a vehicle or platform to cross a fence or wall.

The radio frequency signal communications (h) permits the alarm signal to be transmitted by a radio signa and is received at the alarm panel. This system is used if no line of sight can be established with the protected sector and there is no possibility to lay cables. The maximum range is determined by the customer and the availability of dedicated frequencies. Fiber-optic signal communications (i) employing fiber-optic cable is the most secure way of transmitting the alarm signals. The cable insures that there are no electronic emissions that can be detected and eliminates jamming possibilities by electromagnetic means. The maximum range without re-transmitters is 6000 ft. Twisted pair signal communications (j) are less expensive than fiber-optic cable twisted pair still remains reliable and easy to install. The maximum range is 5000 ft. Micro-wave signal communications (k) are employed when lay cable cannot be laid due to terrain restriction or when radio frequency signals due to radio silence cannot be sent, microwave-signal communications is the best solution. Either a portable or permanent micro-wave transmitter/ receiver pair can be deployed to provide line of sight alarm signal transmission within a narrow band. Finally, dedicated telephone signal communications (1) may be employed if dedicated phone lines are available and the distance to the alarm panel exceeds 6000 ft. The alarm signals can be multiplexed via RS-232 signals. This also allows other signals to be relayed from the area in which the system is installed.

Standard power transmission (m) from standard AC lines using both 110V 60hz to 220v 50hz power can be used for the system. In user-installed applications 24 volt an 12 volt may be employed whereupon less equipment is needed Solar power transmission (n) may be employed in applicatio that are remote and have no power supply, solar power can used for the sensors and the signal transmission. The differences between systems would be determined by the latitude of the installation. Fence Security System

As shown in Fig. 5, fiber-optic cable 7 is interwoven with the chain link fence 5 at a maximum length of 300 ft., referred to as a section. Depending on the security requirements, one or more cables 7 can be mounted on the fence with user defined spacing between them. On t of the fence the barbed wire 6 mounted between the fence extension arms 4 may have a cable mounted alongside of it. On both types of mountings, UV resistant wire ties 11 are applied at 1.5 ft. intervals on the cable. This provides support for the cable and prevents it from having motion independent of the fence. A strain relief 10 is mounted o a fence post 3 approximately every 60 ft, depending on the spacing between the fence posts 3. On top of the fence extension arms 4 a similar strain relief 10 is also mounte At either end of a section of fence the cable is pulled through a fence mounting bracket 9 that allows the cable t be bent through 90 degrees without degrading the security signal. As the cable is routed on the fence post 3 towards the Emitter/i.eceiver module 8 large wire ties 12 will secure the cable to it. Depending on the installation conditions, the power 16 and signal 17 cables can be led along the bottom of the fence or can be laid in conduit (existing or newly installed) . If additional security is required a buried fiber-optic cable 13 can be added. This buried cable is pulled through conduit 18 to protect it from rain wash and rodents that could set-off a false alarm. The result of this installation is that a person attempting to cross the fence, cut through, or attempt to undermine or bury underneath will be detected by the system. Wall Security System

As shown in Fig. 6, wall security encompasses a broad range of applications for which some items have to be installed at the time of initial construction. These items may in some cases be retrofitted but this method is more involved than just a simple installation. The system does provide for short cuts which are dependent on the resources available. The wall 14 which can be made of any material such as brick, concrete or concrete block should have either extension arms 4 or straight posts on the top of it. Using the barbed wire 6 or normal steel wire between the extension arms, the fiber-optic cable 7 is mounted alongside of such wire and secured with wire ties 11 to it. The Emitter/ Receiver module 8 is mounted flush to the wall on the insid of the perimeter. A cable clamp 15 is used to guide the cable flush with the wall. If the possibility exists of undermining of the wall or tunneling, then the buried fiber-optic cable 19 can be used. To prevent motion to the cable independently from the wall 14 or barbed wire 6 a series of cable clamps are used to secure the cable to the wall. In the case of the buried cable 19, conduit is used to prevent the cable from being moved by rain wash or rodents.

Sliding Gate Security System Using a Tensioning Reel As shown in Figs. 7a and 7b, the system is designed to be used on gates that are part of the protected fence. The fiber-optic cable 7 is mounted on a sliding gat 19 in the same manner as the rest of the fence. The cable on the gate is connected to the local Emitter/Receiver module 8 that has is mounted on the gate. Power to and signals from the Emitter/Receiver module on the gate are carried by the power 16 and signal 17 cable. This flexible cable is attached to a tensioning reel 20 which is mounted on the fence post. The tensioning reel collects the cable as someone opens the gate, and spools the cable back out when someone closes the gate. The reel is spring loaded to maintain tension on the cable. The cable that is connected to the fixed portion of the reel is secured to the fence post 3 .

Sliding Gate Security System Using an Armored Cable

As shown in Figs 7c and 7d, an alternative method to use for the sliding gate uses an armored cable guide 21. In this installation, the signals from the fiber-optic cable 7 are gathered by the Emitter/Receiver module 8 which is mounted to the gate. The power 16 and signal 17 cables are enclosed in a armored cable guide and is suspended between the Emitter/Receiver and the fence support. When the gate is opened, the cable relaxes and hangs from the supports. When someone closes the gate, the cable is automatically drawn tight between the supporting points. Sliding Gate Security System Using a Quick Disconnect

As shown in Figs. 7e and 7f, a third method for installation on the sliding gate involves the use of a plug and socket. The fiber-optic cable 7 is mounted on the sliding gate 19 in the same manner as the rest of the fence. The cable 7 is connected to the Emitter/Receiver module 8 that is also mounted on the gate. Power 16 and signal 17 cables to the gate are connected to the fence by a weather proof fiber-optic quick disconnect male and female pair. Before the gate is opened, an operator disconnects the plug and socket. When the operator closes the gate again, the plug and socket are manually reconnected. The socket conducts power and signals from the gate to the cable secured to the fence. Pedestrian Gate Security System

As shown in Fig. 8, the system can be used on swinging gates that are part of the secured fence. A pedestrian gate 23 uses a single fiber-optic cable 7. The installer mounts the cable in such a way that the gate surface area is protected like the adjoining fence. This i accomplished when the gap between the installed fibers on the gate matches the gap between fibers on the fence. The installer then routes the cable to the fence support near the hinge. They then couple this installed cable from the gate to the Emitter/Receiver module 8 that they have previously mounted on the fence support. The installer the inserts the wiring from the Emitter/Receiver module into th buried conduit 18 to protect it from the weather. The purpose of the fiber-optic cable mounted on the gate is to perform the same protective function as any other part of the fence. In addition, the action of opening the gate the will cause the cable to flex, activating the alarm. If it is not possible to continue the cable that is installed on the fence into the gate, then the Emitter/Receiver module can be installed on the gate and the control and power cables can be bridged at the hinge. Vault Security System

As shown in Fig. 9 , the system can be applied to provide security to enclosed rooms and vaults . The cable 7 is installed within the walls, floor and ceiling of a new construction 24. Any attempt to cut through the walls or blast through is with explosives is detected by the cable and triggers an alarm. The spacing between cable is as suc that even if the location of the cable is known one could not enter the room without moving the cable. The advantage of the system is that it cannot be triggered unless a deliberate attempt is made to enter the room. This configuration allows the use of inexpensive construction materials to construct a vault that has a high degree of break-in or breakout resistance. The system can also be integrated into the door to provide complete coverage. Object Security System

As shown in Fig. 10, the system is suitable for providing security for stationary individual objects, eithe in interior or exterior locations. The object to be protected 25 has the fiber-optic cable 7 looped through it at one or more points. The user connects weather proof fiber-optic quick disconnects 22 to permit the fiber to be looped through openings in the object. These connectors allows for speedy installation. The sensitivity is adjuste to where motion cannot disturb it this results in an alarm condition only when the object is forcibly removed from its location. Cutting the cable or pulling it apart at the connector also results in an alarm. The Emitter/Receiver Module 8 is installed in a location not further than 150 ft away from the objects to be secured. The cable is led through conduit 18 to provide a secure location for it to prevent it from being damaged by traffic. Multiple objects can be secured with one cable and multiple cables can be used for large area coverage. Emitter/Receiver units can also be daisy-linked for longer distances. The advantage t this system is that large or small objects, inside or outside, can be secured without any additional methods. Man-Portable Security System

As shown in Fig. 11, system is applicable as a means of providing portable security. The security system is implemented by the user who removably deploys it in an interior or exterior location. One installs the fiber-opti cable 7 by temporarily fixing it to a tree 27 or other objects along the perimeter to be secured by the use of re-usable strain relief connectors 28. The cable 7 is transported on a portable reel 38 and can be re-used. Upon installation of the cable 7 it is connected to the portable Emitter/Receiver module 39 that includes a self-contained power supply using rechargeable batteries. When the system is activated and upon detection of movement in the cable an audio visual alarm is triggered. The alarm signal can also be directed to an output which can trigger remote alarms, relays and other devices such as fuses on mines. When the system is no longer required, the user deactivates the pane and retrieves the fiber-optic cable. Systems can be daisy-linked with other similar units without limit and can also provide additional security to fixed systems. The advantage over trip wire systems is that once triggered the system cannot be overridden. Ground Detection Security System

As shown in Figs. 12a and 12b, the system can be used in the ground as well as other applications . First th ground is prepared by providing adequate drainage and the construction of a concrete tub 29 for the area to be covered. Medium sized gravel 30 is then poured into the tu filling it two thirds of the way. The cable 7 is placed on the gravel at specific intervals and more gravel is added t the tub. Conduit 18 is used to lead the cable above ground and it is connected to the Emitter/Receiver module 8. When an individual or vehicle passes over the gravel bed an alar is triggered. The degree of sensitivity can be set to trigger the alarm for humans or vehicles. This ground detection system is not sensitive to earth tremors or precipitation and provides virtually no false alarms. Bridge Span Security System

As shown in Figs. 13a and 13b, on a bridge span 6 with pylons 70 cable is embedded under the roadbed 69. Thus it is possible to detect changes in the integrity of the structure. The cable is led through conduit 18 within the concrete. This allows it to be maintained, cable can be removed and replaced. The Emitter/Receiver module 8 will process the signal. Fence Mounting Bracket

As shown in Figs. 14a and 14b, the cable must be secured to the fence. The installer should always avoid sharp bends in the cable, since this reduces the sensitivit of the system or could damage the cable. To aid in the reduction of sharp bends, a mounting bracket is provided. This bracket is designed to attach directly to fence suppor posts. As part of the bracket, an elbow shaped metal tube 34 is used to guide the fiber. The metal tube 34 is curved into a right angle and welded 33 to a metal band 31. When the installer inserts the cable 7 into the tube, it exits the tube at a right angle with no sharp bends. The installer uses this bracket at all points that require the cable to be bent. Fence Strain Relief Bracket

As shown in Figs. 15a and 15b, in order to preven the cable 7 from sagging, it is necessary to install a special strain relief. These strain reliefs are designed for fence use and are installed every 60 ft. The strain relief comprises a corrosion resistant metal band 31 to which is welded a small diameter corrosion resistant tube 32. During installation the cable 7 is inserted into the tube 32 and crimped 37 at two locations with a previously specified crimp tool at a specific setting. The crimps den the exterior coating 36 of the cable insuring that the interior plastic fiber 35 is not attenuated. The fence strain relief insures that the cable does not move independently from the fence which would prevent accurate alarms. Power Supply

As shown in Fig. 16, the system operates from standard DC power. This is a description of the methods used to obtain the power.

The primary source of power to the system is from the power mains. This voltage level can be either 110 or 220 volts. The AC power is then converted to a DC voltage level in the switching supply. This voltage is used to bot operate the system as well as recharge the backup battery.

The system also can operate from solar power as a secondary source. Installation of the solar panels, calibrates them to collect energy during daylight. The DC voltage created by the panels consists of a variable voltag level. It is necessary to convert this inconsistent voltag into the constant voltage needed for maintaining the charge on the battery. A DC to DC converter transforms the panel 9 β

voltage to the proper charging voltage. This stable voltag then is used to operate the system as well as charge the batteries. When the solar panels are no longer supplying energy, the battery continues to power the system.

The primary power supplies cannot be assumed to have energy available at all times. During primary power failure, the system uses a power backup technique. This backup is provided with batteries. A lead-acid battery provides the necessary system level voltage. This level is typical of the voltage required for all elements of the system. The system designer determines the capacity of the backup battery during configuration, for each installation. It is dependent on the expected length of time that the system will be operated from the battery. As an example, the standard installation, of 320 receivers, allows the battery usage time to be calculated. For one hour of battery use, this configuration requires at least a 23 amp-hour battery.

The power requirements can be determined for each installation. The batteries can be added in multiples to increase the power capacity needed by larger systems. All other aspects of the power supply remain the same regardles of the size of the installation. Emitter/Receiver module

As shown in Fig. 17, the Emitter/Receiver module is contained in a weatherproof enclosure 61 having openings to permit signal and power as well as the fiber to extend into the enclosure. These openings may have liquid tight connectors 54 installed after the wiring is in place to sea against the weather. The modules in the enclosure are mounted on DIN rails 49. The elements include, emitter modules 47, receiver modules 46, power and signal terminal blocks 48, and a tamper proof switch 50. As described abov in connection with Fig. 2, the Emitter/Receiver module is the signal conversion point in the system. The emitter module uses the power provided to the unit to generate a light signal. This light signal is driven into the optical fiber that is connected to the emitter. On the receiver side, the signal returned by the fiber is detected. The receiver module converts the light signal into an electrica signal. The receiver circuit establishes a stable state at the static signal level. Once stable, any change in the light signal level causes an electrical signal to be generated. This electrical signal is a switched signal tha triggers an alarm when activated. All power and signal is transmitted through hookup wire 51. The modules are mounte on the DIN rails in the enclosure. Wiring to the modules i done with wires that attach to the power and signal blocks also on the DIN rail. These blocks have screw connections that allow the installer to attach the wire to the block. The installer is not required to perform any elaborate preparation of the wire. The installer threads the optical-fiber cable directly into the enclosure through the feed-through opening. They then attach each fiber to either an emitter or a receiver module. Throughout the system, one end of each fiber is connected to an emitter and the other end connected to a receiver. The tamper proof switch is mounted on the inside of the enclosure. It is wired to the signal blocks in the enclosure. The installer brings these signal lines out of the box along with the other signals. When an intruder removes the lid from the enclosure, the switch activates. This sends an alarm signal from the unit to indicate a security violation. Detail of Vault Security System

As shown in Fig. 18, to facilitate the construction and maintenance of the system for vaults, the cable 7 is incased in conduit. The conduit can be located in a solid vault wall permanently. If for any reason the cable needs to be removed, it can be pulled out of the conduit and inserted again. Central Control Unit (CCU)

As shown in Fig. 19, the Central Control unit is the device that collects the signals from the Emitter/ Receiver modules. It is also the location of the backup power supply to the system. It is housed in a weather proof enclosure 61. DIN rails 49 are used to mount the elements in the enclosure. The wiring enters the CCU through liquid tight connectors 54. These signal wires go to terminal blocks 48 on the DIN rails. These signals are then routed to the multiplexer module 63, also in this enclosure. The multiplexer converts the signals which have come from the Emitter/Receiver modules into a transmission signal. A transmitter module 62 then sends the transmission signal from the CCU. Power wiring enters through the liquid tight connectors is routed to terminal blocks that are in the CCU The power obtained is used internally as well as external t the CCU. Power wiring to the other elements of the system is taken by means of the terminal blocks. The power supply 64 is also mounted in the CCU. This power supply module normally maintains a full charge on the backup rechargeable battery 45 through the power supply circuitry 52. In the event that the system primary power is lost, the battery powers all devices connected to the CCU. Signal Interface Module

As shown in Fig. 20, this module comprises a weather proof enclosure 61 and a series of opto-couples 71 on a circuit board. The unit has liquid tight connector 54 through which hookup wire 51 runs to the alarm panel or Central Control Unit and runs in from the Emitter/Receiver module. Weatherproof Quick Disconnect Connector

As shown in Figs. 21a and 21b, this device is a fiber-optic connector 22 that will work under the most severe environmental circumstances. It will survive multiple connect, disconnect operations without degradation of performance. The low signal loss allows many connectors in serial to provide coverage of large amounts of objects within the loop. Man-Portable Security System Module

As shown in Figs. 22a and 22b, the man-portable system is contained in a standard enclosure 54. The enclosure is covered with a weather tight cover. The unit has a rechargeable battery 45 which can be used to power al the elements of the system. An emitter module 47 is used t generate the light signal to the fiber. A receiver module 46 is used to detect the light signal from the fiber. The fiber loop that is installed external to the enclosure is connected to the emitter and receiver through the liquid tight connector 54 in the enclosure. The fiber is connecte by the user with optical connectors. A second water tight connector 55 is used for the signals that can be sent to an alarm panel and to provide the device with primary power. This connector is a mil-spec device that is designed to handle all the electrical connections to the outside of the enclosure. When a primary power source is connected to thi . ^>

connector this source is used to charge the battery or operate the system. Power supply circuitry 52 is included in the enclosure. This circuitry is used to control the charging of the battery. It also is used to activate the internal buzzer 60 and other displays. On the outside of the enclosure are controls and displays. The control swit 56 is a rotary switch used by the operator to activate the unit. This switch will arm and disarm the unit. It will select silent or audible alarm. The sensitivity control 5 allows the user to set the trigger point of the cable. Th first display is the power indicator 55 which is an LED device. It will be lit when the user has armed the unit. The alarm indicator 56 is an LED that will be lit when the alarm is triggered. When the man-portable system is not i use, the container is sealed. While sealed, it can be stored or transported without damage to the components. Detail of Man-Portable Strain Relief

As shown in Figs. 23a and 23b, in field installations of the man-portable system the cable 7 has t have the correct tension on it. This is necessary because of factors such as wind and precipitation that could set o false alarms. The strain relief can provide temporary to permanent tension for the cable. The strain relief comprises a metal half-tube (U profile) with bendable meta lips 43. The cable 7 is laid in the U and the lips are be unto the cable providing enough pressure to hold the cable in place. The half-ι-ube is welded 33 to a hard steel scre 44 which can be turned or hammered into wood, concrete or brick. In situations where there are no objects to place the strain relief on, prepared wooden stakes can be used. The strain relief may be re-used until damaged. Detail of Man-Portable Reel

As shown in Fig. 24, in order to provide portability for the cable for the man-portable version it necessary to use a reel that can be hand carried. The ree consists of a carrying handle 40, bobbin 41 and a wind handle 42. The cable 7 can be deployed rapidly from the reel without snags due to the fact that the cable has very little memory. Multiplexed System Diagram

As shown in Fig. 25, the normal communications between the Central Control Unit and the alarm panel is do with direct wire connections. Thus each sensor would have one pair of dedicated signal lines back to the alarm panel. Alternatively, an installation could use a multiplexed dat line for the signals. The multiplexer in the control box would then require only two signal lines to send the information to the alarm panel. At the panel, a demultiplexer could then recover the sensor data. This zon type has the advantage of easier installation, by reducing the cable size to the alarm panel. Another type of zone, would use fiber optic links to carry the sensor data. This zone would be set up the same as above, but would include a fiber optic driver and receiver on the multiplexed lines. Another type of zone, would use radio waves to carry the sensor data. This zone would be set up using a multiplexer in the same manner, but would include an RF transmitter at the control box, and RF receiver at the panel. The multiplexed lines would then be used to modulate the radio waves. This multiplexer module accepts up to 8 signal lines from protected zones. It multiplexes the signals into a single line. This line can then be connected to a remote de-multiplexer to decode the signal. System Wiring Diagram

It is essential to provide electrical interconnection for the elements of the system. This is done with wires or fiber-optic cable. Referring to Fig. 26, the emitter and receiver modules are connected to the fence mounted fiber. The receiver generates an alarm signal when an intruder deflects the fiber. Each receiver module alarm line is connected to the Central Control Unit. A pair of wires is used to carry the signal from the receiver to the Central Control Unit. One pair of conductors per signal is equal to a zone when wiring the system. These conductors are supplied in the interconnect cable. This cable is part of the wiring kit. For the signal lines, the 22 gauge wire is used. Installation of the power wiring is also done wit a pair of wires. A heavier wire is required for greater distance, or when using multiple Emitter-Receiver Module units. The system is designed to use a multiplexer in the Central Control Unit. It takes the signals from many zones It combines these multiple signals from the many zones into one signal. This multiplexed signal is then sent from the Central Control Unit. The multiplexed signal can be sent o a twisted pair of conductors, or via a fiber optic cable. It also can be sent over a radio link. Installed at the other end of the link, is the complementary conversion device. It converts the signal back into the voltage level required for the de-multiplexer. The de-multiplexer is use at the alarm panel to convert the received signal back into the alarm signals for each of the protected zones. The installer will wire the single line into the de-multiplexer This module reproduces the multiple zone alarm signals. Th installer connects the alarm signals to the alarm panel as if they were wired directly from the receiver. System Integration Flow Diagram

Sensor Monitoring

As shown in Fig. 27A, the zones in the security system must be monitored continuously. The software scans each of the zones. If no alarm conditions exist, the statu displayed on the monitor indicates this cleared state. If the controlling software detects an alarm, the computer displays an alarm state for the affected zone on the monitor. This active display of zone condition is required to inform the operator immediately of the presence of an alarm condition.

Access Control-Card Entry

As shown in Fig. 27B, personnel that are permitte access to the secure area will have been issued an ID card. As shown in Fig. 27B, when access is requested, the access control software reads the card. It then compares the card ID with the database of valid IDs. If the ID is valid, the controlling software will grant the access, and also log th access. Otherwise, the computer logs an invalid access attempt.

Time and Attendance Report

As shown in Fig. 27C, any time that a new operato checks in to the system, the database of operator information is updated by the software. When the operator checks out at the end of the shift, the computer again updates the database. Reports can be generated by the supervisor that show which operators were active on a given day. Also the list of days for any operator can be printed.

Video Image Display

As shown in Fig. 27D, the status of the system can be represented by green and red symbols. The display would normally show only green symbols. When an intruder activates an, the symbol for that alarm would turn red. When the operator selects one of the red symbols, the computer immediately provides additional information. The information could be a graphic picture of the selected zone or instructions for the operator to perform.

Closed Circuit Television

As shown in Fig. 27E, a menu on the control display shows the active camera list. The operator can select one of the cameras from the list. The software activates the switching system to present the video from th selected camera to the TV video screen. When the controlling software has selected a camera, the operator ca control that camera. The operator also can activate the video recorder.

Guard Tours

As shown in Fig. 27F, the guard tour can be obtained from a database of planned tours. The system can selectively deactivate the tour route. Reports along the route allows the scheduled tour software to reactivate the zones after the guard passes. If a guard misses a schedule report, the system alerts the operator and logs an event. When the guard has completed the tour, the alarm control system software returns to standard mode, and the log file 9 -j

records the completed tour.

Elevator Control

As shown in Fig. 27G, the current position of the elevators are monitored. When an intruder has activated an alarm, the software records the current position in the log The elevator can then be deactivated by the operator.

Alarm Monitoring

Figure 27H shows the alarm monitoring. For example, when an intruder deflects a cable, an alarm is issued. The zone that has the alarm is then identified at the alarm panel. The software accesses the database of procedures for that zone. The software then follows the proper procedures for the indicated zone. At the same time the software will make a log entry automatically. The log file is used to save the zone number and the date and time.

Operator Control

As shown in Fig. 271, the options available to an operator are displayed in a menu format on the screen. The operator can then select a function from this menu. The operator also can interact with the program while it performs the selected task. For example, if the video camera is to be activated, the program prompts the operator to select the desired camera from a list.

Modem Control

As shown in Fig. 27J, a remote control function can be used with the system. As shown in Fig. 27J, the remote computer can collect information on the status of th security system. A modem is used to provide the connection A dial-up connection can be made via standard phone lines. The security status then can be made available across the modem connection to the remote computer. This connection t the remote computer is then logged as an event with date an time. An operator at the remote site can control the security system. All of the local functions are available to be activated remotely.

Timed Output Control

As shown in Fig. 27K, the software is designed to maintain a database of timed functions. As shown in Fig. 27K, if lights are to be turned on at a certain hour, the entry in the database will have the time and the procedure for the system to follow. When the current time matches th time listed in the database, the procedure will be activated. This can include deactivation of zones for specified times, without direct operator control. All time events are logged as the computer performs them, in the sam manner as the operator controlled events.

Audio Communications to Alarm Location

As shown in Fig. 27L, shows the control of audio communication. For example, when an intruder triggers an alarm on a fence, the audio alarm would be activated neares that fence. This draws attention to the area, so that identification can be made of the person on the fence by others in the area. Detail of Fiber-Optic Cable

As shown in Fig. 28, the cable consists of a plastic core 65 with a poly-ethylene cladding 66. The outer jacket is made of a U/V resistant poly-ethylene. The inner core has a specific attenuation which gives the cable its unique characteristics. An outer jacket 67 is formulated to provide the correct dampening of vibrations that helps negate vibrations and temperature changes that could transmit false alarms. Fence Strain Relief Bracket

As shown in Figs. 29a and 29b, the cable should bend 90 degrees gradually. The guiding bracket allows the cable to be installed in a variety of application. A metal band 31 is welded 33 to an elbow shaped metal tube 34. When you insert the cable 7 into the bracket it exits the tube at a 90 degrees angle.

In a further preferred embodiment of the present invention (fig. 30) of the so called LightSpeed"' system, a number of LightSpeed lines 72, 73, 74 and 75 respectively, are connected to a casing 76 having a width of e.g. 80 mm and a inner depth of about 65 mm, such that such casing extends along an existing post of a fence. Inside the casing the LightSpeed lines are connected to transmitting/receiving- modules in which transmitting and receiving means for light signals are incorporated. The shown LightSpeed lines comprise multimode or stepped index polymethylmethane acrylene (PMMA) fibre having a diameter of 0.5 mm and onto which a cladding layer of cylindrical form of polyethylene is arranged. If such cable is bent e.g. with a curvature of 10 mm, such bending is detected and reported through a line to a central unit of the alarm control system, as well as is cutting of such LightSpeed line.

The output 80 of a LightSpeed detecting or receiving unit (fig. 31) is preferably connected to a relay unit 81 provided with two output terminals 82 and 83 respectively, and connected to earth and to a voltage regulating unit 84 for regulating voltage between 12-30 V, so that the relay remains in the alarm position after a LightSpeed line is cut or bent. The relay can be of the normally open or normally closed type. After bending or cutting a LightSpeed line the signal between terminals 82 and 83 changes and remains changed with either type of relay. This arrangement also makes the relay and therefor detecting of a security alarm, insensitive to temperature influences or other, which would vary the supply voltage for the relay.

In a preferred embodiment (fig. 32) a central unit 90 is connected to a number of LightSpeed transmitting/receiving-modules 91, 92 etc. for section Si, S2..SN respectively which are interconnected by fibre line 93 and through multiplex unit 94, 95 etc. via fibre lines 96, 97 etc. so that a cable of only four electrical conductors is needed, viz. one conductor 96 leading to the first multiplex module 94, one conductor 98 returning from the last multiplex unit and two conductors for voltage supply, as well as the case may be two light conducting fibers for also preventing of bending and/or cutting of such cables. As the above preferred embodiment is insensitive to weather conditions -it has been tested to withstand lightning pulses of 78.000 Volt- a number of security applications are available with the LightSpeed security system. Apart from security for fences it is possible to include a LightSpeed line in a gutter in which also gravel and/or sand is present so that a trespasser when stepping on such gravel induces bending if a LightSpeed fibre which is detected by the central unit.

Also windows, overhead doors, goods stored in harbors, containers, safes and art objects can be secured by providing such object with one or more LightSpeed lines. It is noted that the above preferred embodiment only detects a variation in the bending, so that a LightSpeed line can be bent with a certain curvature around an object, e.g. also for instance around the post of a fence. If the line is further (or to a less extend) bent, this is detected by a security system according to the present invention.

A further embodiment of the LightSpeed System (not shown) may include connecting and disconnecting optical fibers into and outof connectors, e.g. in a security system including one or more doors, in which one connector is provided on a pivoting or sliding door element.

The present disclosure includes that contained in the appended claims, as well as that of the foregoing description. Although this invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that the numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention.

Claims

Now that the invention has been described, WHAT I CLAIMED IS:

1. A fiber optic security system, comprising: a fiber optic cable; means for transmitting light into one end of said fiber optic cable; said light having a wavelength such that bending of said fiber optic cable attenuates the intensity of said light during transmission therethrough; and means positioned at the other end of said fiber optic cable for receiving said light and sensing the intensity of said light transmitted therethrough and producing an intensity signal proportional to said intensity, said receiver means including means for integrating said intensity signal to produce an integrated signal and switch means responsive to said integrated signal for actuating an alarm signal.

2. The fiber optic security system according to claim 1, wherein said receiver means include means for adjusting said integrated signal supplied to said switch means to provide sensitivity adjustment, for differentiatin said intensity signal relative to time prior to being supplied to said integration means, first means for comparing said integrated signal with a first reference voltage prior to being supplied to said switch means, and second means for comparing said intensity signal with a second reference voltage to produce an output voltage that is supplied to said switch means and wherein said switch means is responsive to said output voltage.

3. The fiber optic security system according to claim 1, including a central control unit for controlling said transmitter means and said receiver means, including a alarm panel connected to said central control unit, said alarm panel controlling the operation of at least one of a camera, recorder, audible alarm, external alarm display and/or lighting, and computer means connected to said alarm panel for providing at least one of operator control, senso monitoring control, audio communication control, timed output control, modem control, guard tours control, access card entry control, time and attendance control, video image display control, closed circuit television control, elevator control, alarm monitoring control and modem control.

4. The fiber optic security systen according to claim 1, 2 or 3, wherein said system is employed in at least one of a fenced security system, sliding gate security system, pedestrian gate security system, object security system, vault security system, bridge span security system and ground detection security system, and including means for communicating among said security systems, said communication means comprising one of a radio signal communication, fiber optic signal communication, twisted pair communication signal, microwave signal communication system and telephone signal communication.

5. The fiber optic security system according to claim 4, wherein said fence security system comprises said fiber optic cable interwoven with chain links of a fence.

6. The fiber optic security system according to claim 4, wherein said wall security system comprises said fiber optic cable extending from a plurality of extension arms positioned on a top portion of said wall.

7. The fiber optic security system according to claim 4, wherein said sliding gate security system comprises a tensioning reel on which said fiber optic cable is wound and tensioned, said tensioning reel being affixed to one of said sliding gate and a fixed portion of a fence with said fiber optic cable extending therebetween, such that the tension in said fiber optic cable remains substantially constant when said sliding gate opens and closes, an armored cable guide affixed to said sliding gate with said fiber optic cable extending from a fixed porion of a fence to said sliding gate , to allow said fiber optic cable to relax and hang when said sliding gate opens, and a two-ended portion of said fiber optic cable rigidly affixed to a fixed portion of a fence and another two-ended portion of said fiber optic cable rigidly affixed to said sliding gate, with said ends of said fiber optic cable portions being respectively connectable by means of a quick-disconnect connector, wherein said quick-disconnect connector is manually disconnected upon opening of said sliding gate.

8. The fiber optic security system according to claim 4, wherein said pedestrian gate security system comprises affixing said fiber optic cable from a fixed portion of a fence to said pedestrian gate such that, upon opening of said pedestrian gate, said fiber optic cable is bent.

9. The fiber optic security system according to claim 4, wherein said vault security system comprises means for affixing said fiber optic cable within walls of said vault.

10. The fiber optic security systems according to claim 4, wherein said object security system comprises means for positioning said fiber optic cable through openings in said object such that said fiber optic cable is bent upon movement of said object.

11. The fiber optic security system according to claim 4, wherein said man-portable security system comprises means for removably connecting said fiber optic cable within a location.

12. The fiber optic security system according to claim 4, wherein said ground detection security system comprises means for positioning said fiber optic cable within a bed of aggregate material such that said fiber optic cable is bent upon movement of said aggregate material.

13. The fiber optic security system according to claim 4, wherein said bridge span security system comprises means for rigidly affixing said fiber optic cable within said bridge such that said fiber optic cable is bent when the integrity of said bridge is compromised.

14. The fiber optic security system according to claims 1-13 including a mounting bracket for connecting said fiber optic cable in a bend to a fence post or the like, said bracket comprising an arcuate tube having an inner diameter greater than an outer diameter of said fiber optic cable, a band for rigidly affixing about said fence post and means for rigidly connecting said tube to said band, and a strain relief bracket for connecting said fiber optic cable to a fence post or the like, said bracket comprising a tube having an inner diameter appreciably greater than an outer- diameter of said fiber optic cable, a band for rigidly affixing around said fence post, and means for rigidly connecting said tube to said band, said tube including inwardly extending crimp protrusions which engage said fiber optic cable, wherein said transmitter means and said receiver means are positioned within a weather-tight enclosure positioned proximate to an area to be monitored.

15. The fiber optic security system according to claims 9, wherein said fiber optic cable is positioned within said conduit permanently installed within said walls of said vault.

16. The fiber optic security system according to anyone of claims 3-15, wherein said central control unit is positioned within a weatherproof enclosure.

17. The fiber optic security system according to anyone of claims 2-16, wherein a plurality of said control units are connected to said alarm panel by means of a ultiplexerde-multiplexer arrangement.

18. The fiber optic security system according to anyone of claims 3-17, wherein said sensor monitoring control comprises means for displaying the current state ol the central command unit on a monitor and displaying any change of said state on said monitor, wherein said access card entry control comprises means for determining an identification associated with each card and maintaining a log for each entry, wherein said time and attendance control includes means for storing time and attendance data and printing reports, wherein said closed circuit television control comprises means for displaying the images from one or more cameras.

19. A fiber optic security system, comprising: a fiber optic cable, means for transmitting light into one end of said fiber optic cable, said light having a wavelength such that bending of said fiber optic cable attenuates the intensity of said light during transmission therethrough and means positioned to the other end of said fiber optic cable for receiving said light and sensing the intensity of said light transmitting therethrough and producing intensity signal proportional to said intensity, wherein said fiber optib cable comprises multimode or stepped index fiber.

20. A fiber optic security system according to anyone of claims 1-19, wherein the fiber comprises polymethylmethane acrylene, preferably having a diameter in the order of magnitude of 0.5 mm.

21. Gutter, provided with sand and/or gravel and with an optic fiber of a security system according to anyone of claims 1-20.