A fence module is adapted for installation without required anchoring buy providing a base frame and a plurality of upright supporting posts extending from the base frame. At least three fence sections extend between the supporting posts. A first fence section at a first extreme end of the fence module, a second fence section at a second extreme end of the fence module, and a third fence section angularly positioned between the first and second fence sections. A pair of vibration sensing modules are used to detect intruders, one applied to the first fence section and a second applied to the third fence section, with the first fence section positioned on the secure end of the protected zone.

FIELD OF THE INVENTION  
       [0001]     The present invention relates to perimeter security and more specifically to a security fence module in a delay-and-detect type system.  
       BACKGROUND  
       [0002]     Physical barriers in the form of fences are used to surround various facilities ranging from private homes to government installations. One type of fence provides a physical barrier, or delay mechanism, which inhibits a potential intruder from gaining access to a protected zone. Such fences includes chain link fences, and razor coil fences. Another type of fence provides both a physical barrier and an alarm, or detection, functionality. Such fences include pressure sensor taut wire fences and rigid fences in combination with vibration sensing modules. This latter type is generally referred to as part of delay-and-detect type system since the fence provides both a delay and a detect function.  
         [0003]     An inherent difficulty with delay and detect fences is the need to balance the quality of detection with adequate delay. An extreme example is a brick wall employed as a high quality delay mechanism with a vibration sensor fitted onto the wall. As may be appreciated, it would require substantial interference with the wall to trigger an alarm in such system thus providing low detection quality. The opposite is also a problem, for example in a system which combines a flexible chain link fence with a vibrations sensor where sensitivity is increased but physical delay properties are reduced. Accordingly, present delay-and-detect systems employ reliable sensing element in a first system and then set the required delay quality by providing a physical barrier placed inward of the detection system. This allows for mounting additional fences, digging trenches, and placing other barriers which do not interfere with the detection functionality and increase delay quality. However, at times, geographic and aesthetic considerations do not allow for extending the width of the perimeter fence as far into the protected zone as is desirable for placing sufficient obstacles for a required delay. Other times, physical soil properties may inhibit the construction of separate supporting structures for a detect system and a delay system. For example, digging may be difficult by way of utility lines running under the fence perimeter. In those instances, it is very difficult to provide a delay element without compromising the sensing capability of the combined system. Accordingly, there is a need for a compact delay-and-detect system which can be deployed over restricted terrain while providing for reliable delay and detect functionality.  
       SUMMARY OF THE INVENTION  
       [0004]     In accordance with the present invention, a fence section is provided. The fence section includes a rectangular shaped planer base frame having a front support beam, and a rear support beam, a first lateral support beam coupled perpendicular to the first and second support beams substantially at respective ends thereof. A second lateral support beam is coupled perpendicular to the first and second support beams substantially at respective ends thereof, at least one additional lateral support beam is coupled in perpendicular to said first and second support beams substantially at respective ends thereof at a position between the first and the second lateral support beams. A first vertical support extends perpendicular to the plane defined by the base frame. The first vertical support is coupled to the base frame substantially proximate to the first lateral support beam. A second vertical support extends perpendicular to the plane defined by the base frame and is coupled to the base frame such that the second vertical support is closer to the front support beam of the base frame than the first vertical support is to the front support beam of the base frame. A third vertical support extends perpendicular to the plane defined by the base frame and is coupled to the base frame substantially proximate to the additional lateral support beam. The third vertical support is coupled to the base frame such that the line between the first vertical support and the third vertical support is substantially perpendicular to at least the first lateral support beam. A fourth vertical support extends perpendicular to the plane defined by the base frame and is coupled to the base frame substantially proximate to the additional lateral support beam. The fourth vertical support is coupled to the base frame such that the line between the second vertical support and the fourth vertical support is substantially perpendicular to at least the first lateral support beam.  
         [0005]     The fence section also includes a first planar fence section is coupled between the first and the third vertical supports and extends from a first end of the first and the third vertical supports to a point proximate a second end of the vertical supports, whereby the first end of the first, and the third vertical supports is coupled to the base frame. A second planar fence section is coupled between the second and fourth vertical supports and extends from a first end of the second and fourth vertical supports to a point proximate a second end of the vertical supports, whereby the first end of the second and fourth vertical supports is coupled to the base frame. A third fence section is coupled between the first end of the second and fourth vertical supports and also between a point along the first and third vertical supports a predefined distance from the first end of the first and third vertical supports, whereby the third fence section defines a plane that forms an acute angle with the plane defined by the base frame at the second and fourth vertical supports. A first sensing module is coupled to the first fence section to sense vibrations applied through the first fence section. Finally, a second sensing module coupled to the third fence section to sense vibrations applied through the third fence section. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]     Embodiments of the invention will now be described, by way of example only, and with reference to the accompanying drawings, in which:  
         [0007]      FIG. 1  illustrates a side view of a fence module of the invention;  
         [0008]      FIG. 2  illustrates a front view of the fence section of  FIG. 1 ;  
         [0009]      FIG. 3  illustrates a top view of the fence section of  FIG. 1 ;  
         [0010]      FIG. 4  illustrates an alternate, anchored embodiment, of the fence module of  FIG. 1 ;  
         [0011]      FIG. 5  illustrates a compact fence module in accordance with the invention; and  
         [0012]      FIG. 6  illustrates an alternate embodiment of a compact fence module in accordance with the invention. 
     
    
     DETAILED DESCRIPTION  
       [0013]      FIG. 1  illustrates a fence section module  20  of a delay-and-detect system in accordance with the invention. The fence section structural support elements include a base frame  21 , a first upright post  22 , and an extension arm  23 . The first upright post  22  is coupled to a first end  24  of the base frame  21  so as to extend substantially perpendicular to the plane defined by base frame. A first end of the extension arm  23  is coupled the same first end  24  of the base frame  21  so as to extend parallel to the base frame. The extension arm  23  includes a lower portion  25  that is parallel to the base frame and a second upright post  26  extending perpendicular from an end of the lower portion. Each frame section includes at least two sets of first upright posts  22  and extension arms  23 . As may be appreciated, adjacent fence modules provide additional structural support elements.  
         [0014]     A first semi-rigid fence section  27  is coupled between each adjacent pair of first upright posts  22 . The first fence section  27  is preferably coupled to the first upright posts  22  so as to provide a generally flat vertical fence plane extending parallel to the vertical plane defined by the first upright posts. In one embodiment, the first fence section  27  extends in line with the upper edges of the first upright posts  22 , as is illustrated in  FIG. 1 . In another embodiment, the first fence section  27  extends beyond the edge of the first upright posts  22 . A second semi-rigid fence section  28  is coupled between second upright posts  26  of adjacent extension arms  23 . The second fence section  28  is preferably coupled to the second upright posts  26  so as to provide a generally flat vertical plane extending parallel to the vertical plane defined by the upright supports  26 . In the embodiment illustrated in  FIG. 1 , the second fence section extends beyond the edge of the second upright posts  26 . In other embodiments, the second fence section extends only to the edge of the second upright posts  26  ( FIG. 5 ). A third semi-rigid fence section  29  is coupled between the second upright posts  26  and a point located a short distance along the first upright post  22  from the connection point of the first upright post and the base frame  21 . In one embodiment, the third fence section  29  is coupled so as to form an acute angle between the third fence section and the extension arm lower portion  25 . In one embodiment, this angle is about  30  degrees. In the illustrated embodiment, an extension portion  30  of the third section  29  is positioned parallel to the second fence section and is supported by the second upright posts  26 .  
         [0015]     A first vibration sensing module  31  is coupled to the first fence section  27  so as to sense disturbances of the first fence section by a possible intruder. A second vibration sensing module  32  is coupled to the third fence section  29  so as to sense disturbances of the third fence section. As may be appreciated, the first vibration sensing module  31  and the second vibration sensing module  32  may each include a plurality of sensors equally spaced along the first fence section  24  and the third fence section  29  or a continuous sensing module such as a fiber optic cable.  
         [0016]      FIG. 2  illustrates a front view of the fence module  20  of  FIG. 1 . A pair of first upright posts  22  are shown positioned in perpendicular to the base frame  21 .  
         [0017]      FIG. 3  illustrates a top view of the fence module of  FIG. 1 . In the illustrated embodiment, each base frame  21  includes three parallel longitudinal beams  40 ,  41 ,  42  and five parallel lateral beams  43 ,  44 ,  45 ,  56 ,  47 . Two of the longitudinal beams serve as a front beam  40  and as a rear beam  42  of the base frame. Two of the lateral beams serve as end beams  43 ,  47 . As discussed with reference to  FIGS. 1 and 2 , the first upright posts  22  and the extension arms  23  are coupled to the front beam  40  of the base frame. In one embodiment, these connection points proximate to the connection points  52 ,  53  coupling the end lateral beam  43  and the central lateral beam  45  to the front beam  40 . In the illustrated embodiment, no support section elements are coupled to one of the two end beams  47 .  
         [0018]     To provide a continuous perimeter fence, adjacent base frames are initially joined by connecting an end beam  47 ,  49  which does not include supporting structure to an end beam  43 ,  48  on an adjacent module which includes supporting structure. As may be appreciated, in some embodiments, the base from is coupled to other base frames before any supporting structure is installed.  
         [0019]     In some embodiments, the base frame  21  is anchored to the underlying substrate by anchor elements (not shown) positioned adjacent to beams of the base frame. Accordingly, the optional anchoring elements are placed at various locations within the interior of the frame defined by the end beams  43 ,  47 , and the front and rear beams  40 ,  42 , as permitted by terrain conditions. This anchoring is much more flexible than prior methods which required linear anchoring, at points along the length of a fence section where supporting posts are to be situated.  
         [0020]     As illustrated in  FIG. 1 , in one embodiment, a razor coil configuration  33  is placed on the base frame  21  of the fence module, adjacent to the upright support post  22 , to provide additional delay mechanism. In the illustrated razor coil configuration, a pair of braces  34  are used to secure razor coil elements  35  to one another so as to provide for a rigid pyramid-like coil structure  33 .  
         [0021]     As may be appreciated, a plurality of fence modules are coupled together as discussed above to form a barrier extending from a first fence module to a final module at an opposite end of the barrier. The barrier modules are positioned such that the extension arms  23  are facing the exterior, or non-secure, side of the barrier.  
         [0022]     In operation, the second fence section  28 , coupled to the second upright posts  26 , serves as a delay mechanism to inhibit access to the sensor modules  31 ,  32 , and prevent objects from striking the third fence section or the first fence section and thereby trigger a false alarm. If an intruder gains access through the second fence section  28 , contact will be made with the third fence section  29 , which is positioned at an angle extending from the base of the second fence section. The second vibration sensing module  32  senses such contact and reports an alarm condition. An attempt to bypass the detection provided by the third fence section  29  and directly jump onto or climb the first fence section  27  will be detected by the first vibration sensing module  31  coupled to the first fence section. The first fence section  27  also serves to delay an intruder so as to allow time for security personnel to arrive at the alarm location when an alarm is triggered by contact with the third fence section or the first fence section  27 . Additionally delay is provided by the razor coil configuration  33  placed beyond the first fence section  27  in the illustrated embodiment.  
         [0023]     As may be appreciated, the use of the angular third fence section  29  provides for an early alarm indication, prior to the time an intruder attempts to bypass the first fence section  27 . Furthermore, the rate of false alarms resulting from animal contact with the third fence section  29  is reduced by placing the third fence section behind the second fence section  28 . Moreover, the second fence section  28  prevents tampering with the sensors  31 ,  32  on the first fence section  27  and the third fence section  29 . The fence section configuration of the invention provides early detection of potential intrusion at substantially lower costs than those associated with prior art configurations where independent sensing systems are placed in front of a physical barrier, such as by placing a microwave system in front of a razor wire fence. The third fence section configuration is also substantially cheaper than pressure or vibration sensing means buried in the ground in front of the physical barrier. Moreover, such buried sensing systems may not be suitable where conditions do not allow for digging. Additionally, the third fence section configuration provides a compact physical barrier that can be placed in space restricted environment.  
         [0024]      FIG. 4  illustrates an embodiment of a fence module in accordance with the invention, where the base frame is replaced by a ground anchor, provided below the first upright posts  22 A. Where conditions allow anchoring, a fence module of the invention, as illustrated in  FIG. 4 , nonetheless provides advantages over prior systems by the high delay and detection capabilities relative to the overall dimensions of the module. An anchoring extension  56  is provided from the first upright post  22 A so as to extend below the supporting surface, preferably in a underground cavity. The first upright support post  22 A is preferably anchored within a rigid anchoring substance  55  such as concrete. An optional supporting sleeve  54  is provided around the substrate cavity so as to (ADD reason). As may be appreciated, various anchoring techniques may be used in other embodiments without departing from the spirit of the invention.  
         [0025]      FIG. 5  illustrates an alternate configuration of a fence module of the invention, which is configured for use in restricted spaces. The fence module  59  is intended for use in areas where topographical or environmental conditions do not allow for placement of configurations such as those in  FIG. 1 . The fence module  59  maintains the overall configuration of the invention by employing a pair of supporting posts  61 ,  62 , and a base frame  21 A. The base frame  21 A is constructed substantially as discusses with reference to the base frame of  FIG. 3 , with differences including different connection points to the supporting posts as may be appreciated. Sensor modules  66 ,  67 , are provided on a first fence section  64  of the first supporting post  61 . A second fence section  63  is also provided on the second supporting post  62  for additional delay functionality. A pair of razor coils  68  are provided above the first and second supporting posts  61 ,  62  so as to provide additional delay when an intruder attempts to climb over the fence module  59 . An advantage of the fence module  59  is that it does not require anchoring and can be installed and removed without disturbing the underlying substrate. Accordingly, the fence module  59 , as well as the fence module of  FIG. 1  are suitable for installing over access roads, above sewage pipes and other utilities, and over rocky terrain.  
         [0026]      FIG. 6  illustrates a fence module  69  in accordance with the invention, which is configured for placement adjacent to an existing fence or other structure. The fence module includes a first supporting post  22 B, a base frame  21 B, and a second supporting post  72 . The first support post  22 B and the second supporting post  72  are coupled to the base frame  21 B so as to extend perpendicular from the base frame. A first fence section  27 B is coupled between adjacent first supporting posts. A second fence section  28 B is coupled between adjacent second supporting posts  72 . A third fence section  29 B is coupled between the second supporting posts  72 , and the first supporting posts  22 B. The third fence section  29 B is coupled between the second supporting posts  72  and the first supporting posts  22 B so as to form a acute angle with the base frame  21 B as is shown in  FIG. 6 . A first sensor module  31 B is coupled to the first fence section  27 B. A second sensor module  32 B is coupled to the third fence section  29 B. A plurality of razor coils  74  is provided on the base frame behind the first fence section so as to occupy a space between the first fence section and an existing fence  76 . Accordingly, the fence module of  FIG. 6  provides delay and detection capabilities in a restricted space environment, without interference with the underlying substrate and in a configuration which maximizes delay while providing reliable sensing functionality (i.e., low false alarms, high detection reliability).  
         [0027]     Although the present invention was discussed in terms of certain preferred embodiments, the invention is not limited to such embodiments. A person of ordinary skill in the art will appreciate that numerous variations and combinations of the features set forth above can be utilized without departing from the present invention as set forth in the claims. Thus, the scope of the invention should not be limited by the preceding description but should be ascertained by reference to claims that follow.