Abstract:
A system of remotely locatable sentries or watchtowers operate as part of a network of such sentries or towers for securing a border or perimeter over a wide area. A sensor array, including particularly an array of video cameras, provides for detection, tracking and identification of a target. The sentry or watch towers include non-lethal, sound-based instrumentalities for discouraging entry into and passage through a secured zone of the target.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The invention relates to wide area surveillance and is specifically directed to a robust, outdoor automated sentry equipped both for monitoring an area and for challenging unauthorized entry to the area under surveillance. 
         [0003]    2. Description of the Problem 
         [0004]    Unmanned, wide area video monitoring for perimeter or boundary control has become steadily more common in recent years as cameras and monitor components have declined in price. Data processing and network communication links are capable of handling large quantities of digitized, raw data. Video monitoring can work under both daylight conditions, using the usual visual bandwidth, and under low light conditions using the near infrared spectrum. Techniques for automated identification of regions of an image with a high likelihood of corresponding to an object have been developed. The various techniques of object recognition require associating groups of pixels together as the “object”. Once an object has been identified, the object can be characterized by shape (including a dynamically changing shape as might be produced by a flock of birds), form and expected location. An identified object may be further characterized by trajectory and velocity information. Selected data was characterized in U.S. Pat. No. 6,947,590 as pixel metadata. 
         [0005]    While monitoring of an area is well developed, most security systems have relied on directing a human to the locale of a detected intrusion. The lack of a non-lethal or non-crippling methods of repelling intruders has also hampered deployment of automatic or remotely controlled instrumentalities for discouraging encroachment. 
       SUMMARY OF THE INVENTION 
       [0006]    The invention utilizes remotely locatable sentries or watchtowers/masts, supporting monitoring elements operable as part of a network of such sentries or towers for securing a border or perimeter over a wide area. The sentry or watch towers include video monitoring systems combined with non-lethal, sound-based instrumentalities for discouraging entry into and passage through a secured zone. Alternative non-lethal measures may include laser dazzlers or microwave devices. Sentries may be mobile or airborne. The towers are fixed positionally and serve as redoubts, intended to limit unauthorized tampering or disabling of surveillance and other equipment mounted on the tower. The tower also increases the field of coverage of the sensors by raising them well above the surrounding terrain. Local power is provided by conventional, buried power lines if available or by solar cells and batteries or a generator. A computer, located either locally or located remotely and accessed over a network data link provides for automatic data capture for archiving and analysis of the images collected by cameras located on the tower which cover a field of view around the tower. Objects passing into or through the field are located and characterized, preferably using algorithms now known in the field such as trajectory algorithms which match trajectory behavior with identification of the object. It is anticipated that the system will be calibrated for the detection of human infiltrators, but the system could readily be applied to animal control. An acoustic projector is installed on an altazimuth mount allowing it to be aimed under the control of the computer or an operator. Based on the tentative identification and the location of the object, an automated message may be broadcast over the projector targeted on the object. Under automatic operation or operator control the acoustic projector may be used to hit the object with discomforting sound beams or microwave radiation in order to discourage further penetration of the zone into the secured area. Communication between the tower and the operator is over a bidirectional communication link between the computer and the operator station. The acoustic projector may include acoustic sensors allowing use of the acoustic projector as a listening device both to aid in automatic identification of a target, to allow automatic or operator communication, and even to allow dialogue with the target. The ability to eavesdrop on conversations between people moving through the field of view may allow an operator to obtain information useful to effective dialogue. 
         [0007]    Additional effects, features and advantages will be apparent in the written description that follows. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself however, as well as a preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
           [0009]      FIG. 1  is a perspective view of a watchtower for the invention. 
           [0010]      FIG. 2  is an elevation view of the watchtower of  FIG. 1 . 
           [0011]      FIG. 3  is a front elevation of a camera stand and low dispersion, sound collector/projector used to implement monitoring and control features of the invention and located at the top of the watchtower of  FIG. 1 . 
           [0012]      FIG. 4  is a top plan view of the camera stand of  FIG. 3 . 
           [0013]      FIG. 5  is a map illustrating fields of view for a series of watchtowers. 
           [0014]      FIG. 6  is a block diagram of the system of the invention. 
           [0015]      FIGS. 7A-E  are high level flow charts illustrating a method of implementing the invention. 
           [0016]      FIG. 8  is a cross-sectional view of a low dispersion, focusing sound collector and projector used with the invention. 
           [0017]      FIG. 9  is a front elevation of the projector of  FIG. 8 . 
           [0018]      FIG. 10  is a menu of operator options for manual control of a watchtower. 
           [0019]      FIG. 11  is a perspective view of a microwave radiator dish suitable for installation on a top or on a mobile platform used in carrying monitoring elements of the invention. 
           [0020]      FIG. 12  is a front plan view of a combination microwave radiator and acoustic energy radiator. 
           [0021]      FIG. 13  is a cross sectional view of a combination microwave radiator and acoustic energy radiator of  FIG. 12 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0022]    Referring to  FIG. 1  a watchtower  10  used to implement area monitoring and securing is shown. Watchtower  10  is anticipated to be one of plurality of towers disposed at approximately 1 kilometer intervals along a boundary or perimeter of a region to be secured. Watchtower  10  has three major sections, a reinforced base  12 , a retractable mast  23  supported on and extending upwardly from the reinforced base  12 , and a top  30  located at an elevated location on the retractable mast  23 . Top  30  carries the local monitoring equipment, deterrent devices, wireless communication instrumentalities and data processing elements for a broad area security system. 
         [0023]    Reinforced base  12  has an interior which is accessed through a port  20 . Reinforced base  12  may be used to house a power supply such as batteries or a diesel generator. Reinforced base  12  may be further protected by placing bollards  22  around the reinforced base in a protective constellation. 
         [0024]    The present invention provides deterrence features which are capable of automatic or manual operation. The deterrence instrumentalities are one or more energy projectors such as energy projector  11  installed on top  30 . While in theory various types of “energy” may be projected, the preferred embodiment of the present invention utilizes acoustic energy, and the projector is an acoustic projector such as described in a copending United States Patent Application for an Acoustic Energy Projection System, appl. No. 11/454,914, filed 16 Jun. 2006 by the present inventor, Curt Graber. The &#39;914 application is hereby incorporated by reference. 
         [0025]    In order to function this system must provide for detection of intruders. Fixed cameras  32  and a movable targeting camera  34  are the principal tools used to implement monitoring. 
         [0026]    Energy projector  11  and targeting camera  34  are supported on an altazimuth mount  36  which is in turn supported directly or indirectly from top  30 . Directly supported by top  30  are a plurality of fixed cameras  32  arranged to provide coverage of an area adjacent or near to watchtower  10 . Top  30  may also carry solar panels (not shown) if such are used as part of the power supply system, a spotlight (a detection aid, not shown), which would be added to the altazimuth mount  36 , a laser dazzler (a deterrent, not shown), a focused microwave projector of millimeter wavelength (as a substitute or a supplement to the sound projector) and a housing  40  for local data processing and wireless communication equipment. Local data processing and wireless communication equipment may also be located in a mast cap  46  directly below top  30  or within the energy projector  11 . 
         [0027]      FIGS. 2A-B  illustrate possible locations for equipment used with watchtower  10 . A power supply  44 , such as batteries or a diesel engine, are located protected in reinforced base  12 . Upper and middle mast sections  28 ,  26  nest in base mast section  24  as indicated by arrow “R”. A mast retraction and raising system  42  is located within mast base section  24 . Energy projector  11  is preferably an acoustic energy projector base on a cone reflector  14 .  FIG. 38  illustrates the relative size of an average person against the size of the watchtower  10 . 
         [0028]      FIGS. 3 and 4  provide more detailed views of the top  30 , and the arrangement of equipment on the top. A laser dazzler  48  or spotlight can be positioned on an altazimuth mount  36  as shown. A microwave projector could be located centered in an LDAP projector, substituting for the inner cone  14 . Fixed cameras  32  are installed on mounts  48  which allow for adjustment on installation to take into account terrain of the area to be covered. Generally four fixed cameras  32  are used to provide a field of view (FOV) with an approximately 180 degree arc around the watchtower. Projector  11  is covered by a screen  50  which obscures the internal arrangement of the projector and thereby renders more difficult any action to render the projector inoperable. 
         [0029]      FIG. 5  illustrates border and perimeter control using a network of three watchtowers  10 A-C. Watchtowers  10 A-C have a wireless connection  67  to a monitoring station  68 , which may be remotely located and which is preferably manned. Watchtowers  10 A-C have fields of view  60 ,  61 ,  62 , which are illustrated as overlapping, though it is not required that this be so to provide surveillance over an area  52  intrusion into which by a person  58  is supposed to be detected. Area  52  is divided into zones  51 ,  52 ,  53 , although, depending upon the application, the number of zones could be increased or decreased. Zone  51  may be termed a warning zone. A person  58  moving through this zone along trajectory A might be periodically warned that they were approaching areas to which entry was forbidden them. Typically no direct action would be taken to exclude the person beyond periodic repetitions of the warning so long as the person did not cross into the next area. Warning frequency might be made dependent upon the degree of penetration into zone  51 . A flock  57  of birds is shown moving through zone  52  on trajectory B. Data processing equipment could be programmed to recognize flocks as objects not of interest, which would result in no action being taken. A person in the same area would receive heightened warnings in this zone and ordered to retreat. Zone  53  may be termed an exclusion zone. Selected objects moving through this area would be subject to exclusion. A four legged animal  59  is shown in the area. If the system were applied to wildlife control around a major park it could be used to monitor movement of a predator, such as a wolf, leaving the park in the direction of agricultural areas, in which case the system could respond with non-lethal deterrent actions as described below. A contour line  56  is illustrated winding its way in and out of area  52 . The system can use trajectory analysis as a way of identifying objects and as a way of characterizing objects as being of interest. The physical terrain covered by a given watchtower can, particularly if rugged, affect the trajectory of objects (e.g., relative bearing, acceleration, velocity) moving through the fixed cameras&#39; field of view. Knowledge of local contour may control the selection of the trajectories of interest for watchtower  10 C but not  10 A, but it is not necessary that the trajectories of interest be determined be preprogrammed. They may be identified by operators based on experience. 
         [0030]    Hardware support for the present invention can be configured in a variety of ways.  FIG. 6  is a high level block diagram of an illustrative arrangement of a system  101  providing for such hardware support. A watchtower  10  may be equipped with a local computer  126  which receives power from a local, or secure commercial, power source  128 . Local computer  126  generates control signals for altazimuth positioning motors  124  which allow deterrent devices  122 , the low dispersion acoustic projector and sound collector (LDAP)  111  and the targeting camera  34  to be aimed. Control outputs to the deterrent devices and loudspeakers used for acoustic energy projection are applied by the local computer to deterrent devices  122  and LDAP  111 . Sound collected by LDAP  111  microphones is in turn applied to local computer  126  as is the video signal generated by targeting camera  34 . The targeting camera  34  has a telescopic zoom  130  under the automatic control of local computer  126 . The remote operator may direct responses of the local computer  126  to the extent permitted by programming. Fixed cameras  32  also provide video signals to local computer  126 . The video data may be archived locally or on a database server. As will be understood by those skilled in the art all signals are subject to digital signal processing before application to the local computer  126 . 
         [0031]    It is anticipated that one human operator will be assigned groups of adjacent watchtowers  10 . Such operators can be located remotely at an operator station  68  equipped with an operator station computer  140  and appropriate input and output devices  142 ,  144  allowing the operator to monitor anything picked up by the cameras and sound collecting system of a watchtower or sentry and to exercise control over the deterrent devices  122  such as the LDAP  111  acoustic energy projector. Inputs  142  will naturally include a pointing device and a keyboard, but will preferably include a microphone for generating audio messages to be transmitted by the LDAP  111  and may also include a joystick for aiming the systems supported on the altazimuth mount and for control of the zoom  130  feature. 
         [0032]    System  101  provides a network to connect the local computers  126  of a group of watchtowers  10  to the operator station  68 . Network  120  is illustrated as providing access to database servers  104 , which may be located at the operator station  68 , or dispersed among various agencies of the institution charged with control of the system. Database servers  104  may include object identification characteristics supporting the automatic determination by particular watchtowers  10  that an object entering the field of view (FOV) of fixed cameras  32  is an object of interest. Database servers  104  may provide facial and voice recognition systems allowing instant identification of known individuals entering an area. Other databases  104  might include one of criminal records, etc., as well as object qualification criteria. 
         [0033]    Referring now to  FIGS. 7A-E , implementation of the system is exemplified by relation of the functions carried out by system  101  to a flow chart. System  101 , and more particularly a given watchtower  10  within system  101 , normally operates in an automatic mode until detection of an event which triggers an alarm for an operator. Essentially fixed cameras generate of an image for a field of view which is scanned for motion of objects within the FOV (step  202 ). As long as object motion is not detected (step  204 , the NO branch) the routine cycles through the object and motion detection operations without spawning of a sub-process. Once motion of an object is detected (illustrated as the YES branch from step  204 ), a sub-process is spawned and the object tagged (step  206 ). The detection of “object motion” may appear to assume that an object is identified before its motion can be detected, however, motion of an object may be inferred from value changes of a group of localized pixels before “object” identification has occurred. Thus step  204  can be taken as simultaneous qualification of changing pixel values used for both object and motion detection. 
         [0034]    It is intended that system  101  provide a tentative identification of objects, first by associating groups of pixels in the image with one another as an object based on pixel data and metadata than characterization of the object by shape, size, form, and trajectory. Steps  208 ,  210  and  212  refer to characterization and identification of the object. Information accumulated about an object includes its shape, form, size (from range) and its trajectory. All of these object characteristics may be compared to a library of objects previously determined to be of possible interest. Because terrain effects can alter measurable characteristics of images of physically like objects, such as typical trajectories, databases of objects may be limited to a locale, even if stored on a remote server. The characteristics should be defined as ranges to avoid generation of an overly large database. 
         [0035]    Development of the object database for a locale is expected to be heuristic. That is, there will initially be few objects in the database, and objects will be qualified based on operator input. Accordingly, step  214  provides for comparison to the library of an object for which data and metadata has been generated. If no match is generated step  216  is executed to alert an operator and the object is made the current focus of the local watchtower(s) which have it “in sight”, that is the targeting camera  34  is used to track the unidentified object. At step  218  the object is identified as being either “of interest” or “not of interest”. Next, at step  220  the routine branches between objects of interest and those not of interest. Objects that were identified at step  214  are also handled at step  220 . Objects of interest follow A to  FIG. 7B . Other objects result in the subprocess following B to  FIG. 7C . 
         [0036]    Objects, once identified, can be considered as logically separate from the field of view as indicated at step  222 . It is possible that more than one object of interest is moving through the field of view, so a count is kept of the number of objects at step  224 . One reason for this is that, as the system is presently configured, only one targeting camera  34  is provided per tower, though it would be possible to provide more than one. At step  226  an operator is notified of the detection of an object of interest, as well as the location. If the object count is greater than one, and only one targeting camera is available it is necessary to set (and repeatedly reset) one object as the current focus which the targeting camera will track. Thus at step  228 , if the count is not greater than one, the focus is set to the only current object of interest in the field of view (step  230 ). If the object of interest count is greater than one a focus object must be selected following the YES branch from step  228 . At step  236  a subroutine to select the focus is called, and, after a focus has been returned, or set at step  230 , the process moves on to step  234  to determine if a focus object has made an incursion into a surveillance or exclusion area. If No incursion is detected path “C” is followed from step  234 . If an incursion has been detected the YES branch is followed from step  234  to step “D”. 
         [0037]    Turning to  FIG. 7C , processing of a object which is not of interest (step  238 ) is considered. Such an object is excluded from the field of view at step  240  until the conditions for terminating the subprocess, such as prolonged non-movement, or long repeated cyclic movement (such as a tree blowing in the wind), cause a time out at step  242 . 
         [0038]    The process of  FIG. 7D  represents the process called at step  236  to determine a focus from a plurality of objects of interest. At step  244  the individual objects are scored by selected criteria, such as proximity to the area under control, or, if trajectory considerations are used, estimated time until the object will clear the zone under surveillance in the direction of an area which the object is to excluded from. The focus is set to the highest scoring object, which is returned to the calling process. The process of  FIG. 7D  continues as a background process. Following step  246  step  248  is executed to determine if the process has been interrupted by operator action. If yes a delay loop (step  250 ) is entered along the NO branch from step  248 . If not the NO branch is followed to step  252  to execute the object termination conditions. If all objects remain viable the NO branch is followed from step  252  to step  244  and to rescore of the objects of interest. If an object has met the termination conditions, the YES branch is followed to step  254  to terminate the object and decrement the count of objects. At step  256  it is determined if a plurality of objects of interest remain in the field of view, and if so, the process loops back to rescore the surviving objects. If the count is less than two the subprocess is terminated until recalled. 
         [0039]      FIG. 7E  reflects the handling of movement of objects of interest into and through the various zones of  FIG. 6 . These steps follow after detection of an incursion in step  234 . At step  258  the remote operator is alerted. The operator may intervene at any time (indeed no alert is required), however, operator assumption of control is reflected by a decision box at step  260 . The NO branch from step  260  reflects the operator leaving the system on automatic mode. The process of the  FIG. 7E  is entered only after an incursion into at least zone  1  (or the least restrictive zone). Therefore it is only necessary to determine if the object has progressed into zones  2  or  3 , or retreated. 
         [0040]    At step  262  the range to the object is taken. This may be accomplished in a number of ways, for example, if an object is in an area of two intersecting fields to view relative bearings from two towers may be taken to obtain a range by triangulation. More typically a laser range finder, a radar system or an echo location system mounted on the altazimuth mount is employed. Range markers may even be placed in the field of view. Once a range is taken it can be determined if the object of interest is inside the exclusion zone or not. If not, the NO branch is taken and a warning issued at step  280 . After a delay another range to the object of interest is taken to determine if the object has retreated outside of the warning zone (step  282 ). If Yes the process can be exited. If No, the process returns to step  262  to determine if the exclusion zone has been entered. Once the exclusion threshold is crossed and the YES branch followed from step  262  it is determined if the object has crossed into the response zone. If NOT, the NO branch is followed from step  264  to step  268  and the threat level is raised to reflect the increased threat level represented by the object. Automatic responses at this point may include the projection of uncomfortable sound or microwave radiation toward the target or use of a laser dazzler. Following use of the deterrent appropriate to the level of incursion, it is determined if the object has retreated at step  270 . If YES, the process returns to step  262  to determine if the object continues to retreat. If the object does not retreat the process loops back to step  264  to determine if penetration of the area progresses. If YES, step  266  follows step  264  because the object has moved into a response zone and the highest level deterrent is deployed. 
         [0041]    Returning now to the circumstance where an operator assumes control along the YES branch from step  260 . Step  272  simply notes that options are displayed to the operator and responses taken as the operator instructs. Step  274  following step  272  reflects return to automatic control, either by the operator forcing the system not to follow a target or back into the automatic response mode. 
         [0042]    Referring to  FIGS. 8 and 9  an acoustic radiator and collector incorporates a reflector with an inner cone surface and an outer annular reflecting surface suitable for use in the system of the present invention. The particular configuration is by way of example only, and it is not the only such system which could be used. However, the use of an inner cone reflector is favored because, conventionally, sound focusing system are based on a simple concave dish with the transducer element mounted centered in the dish. Such systems are more vulnerable to damage by gunfire than the present system. The cone reflecting system allows more acoustic energy to be input into the system. The inner reflecting surface  82  is provided by the cone reflector  14 , which is preserved from the first embodiment of the invention. A second, outer reflecting surface  84  is provided by a forward concave annular ring  16 . Outer reflecting surface  84  is preferably parabolic in its sections, but differs from a conventional parabolic dish in that the bases of the parabolic sections to not meet at a single point in the base of the dish, but instead surround an annular gap in which cone reflector  14  may be placed. Outer reflective curve  84  can be fitted to curves other than parabolic curves. A radial speaker/microphone housing  18  is located centered under the inner cone  14 . The housing  18  may be moved in and out (double headed arrow F) parallel to the radiating axis of the system to change the range to its focal point forward from the dish. Outer ring  74  is an array of microphones for collecting sound. Where the system is used for controlling the movement of people across a border it is believed that it could be used to eavesdrop on people at great distances, and an operator could then listen to any conversation, possibly to the extent of learning the identity of the people, or at least the names they are using among themselves. The operator could then use the system literally to talk to the individuals on a first name basis. If only an inner cone is used, microphones may be interspersed with the transducers. Housing  78  tucked under the cone  14  is used to house system electronics. 
         [0043]    A radiator/collector used in the present system may take many forms, but that illustrated here has several advanages. Where more than one reflecting surface is used the radiant axes of the surfaces are coincident. 
         [0044]      FIG. 10  reflects a menu of options which may selected from by an operator. As mentioned already the system can allow the operator to eavesdrop (listen) or speak. He/she can select identity checks, including criminal records if available. The deterrent systems available can be displayed. Any other options available may be shown. For example, a system including GPS on response vehicles may be able to display response times. Search lights may be made available, etc. As will now be apparent to those skilled in the art, video cameras may be provided in infrared as well as visible light. The system may be automatically programmed to direct a variety of irritating sounds or microwave radiation toward an intruder. 
         [0045]    Microwave projectors have been proposed which operate in a frequency range where the microwave radiation causes a burning sensation to an animal exposed thereto without actual tissue damage. A microwave projector  300  may be built based on similar collecting principals proposed for the acoustic projectors which the preferred energy projection device used here. An example of such a system in shown in  FIG. 11 , where a microwave projector  300  is constructed based on a ring  305  of microwave generators  304 , oriented inwardly to direct energy against a central spike  302  for common reflection forward from the spike along a projection axis. 
         [0046]    Referring to  FIGS. 12 and 13 , a microwave projector  300  may be combined with an acoustic projector as a mixed energy type projector  340 . The ring of microwave generators  304  are located in an inwardly oriented ring backed up against a plurality of outwardly oriented acoustic projectors  312  which direct sound energy into a conic section ring  310  for projection on the same axis as the microwave energy. Base units  316  are placed under the rings of microwave generators  304  and acoustic projectors  312 . 
         [0047]    The present invention provides a readily deployable surveillance and intrusion deterrence system. While operable in an automatic mode, it allows human intervention to tailor its response to fit the situation on the ground. 
         [0048]    While the invention is shown in only a few of its forms, it is not thus limited but is susceptible to various changes and modifications without departing from the spirit and scope of the invention.