Abstract:
A system and apparatus for detecting and neutralizing remotely activated explosive devices in a combat zone, especially one of relatively limited geographic area such as an urban setting. The apparatus is configured for mounting on or within an airborne drone and includes both transmitting and receiving circuits and antennas. The apparatus detects radio transmissions by analyzing received signals using standard RF direction finding techniques and a spectrum analyzer or other signal processing circuitry. Signals may be classified as threats using predetermined criteria, and the direction of threat signals may be assessed to allow for a determination of an enemy position from which an explosive is to be detonated. The apparatus also transmits a jamming signal which may serve to detonate devices within the dynamic RF footprint of the transmitting antenna. The drone also includes a highly directional low frequency audio device which is periodically directed randomly and at suspected enemy positions.

Description:
BACKGROUND OF INVENTION 
       [0001]    The present invention is directed to electronic and audio countermeasures for use in a wartime environment. More specifically, the invention concerns a device which can use both electronic and audio countermeasures to explode or deactivate various types of remotely controlled or condition responsive explosive devices such as IEDs and land mines. 
         [0002]    Many types of devices, systems, and methods have been developed over the years to counter stationary explosive devices of the type configured for use in a wartime environment. These devices, which include land mines and radio controlled explosives are particularly effective in population dense environments such as those encountered in an urban warfare scenario. Of particular concern of late is the so called IED or improvised explosive device, which is relatively compact and may be remotely activated by e.g., an RF signal, and have even been known to be activated by cell phones connected to the IED so as to trigger an explosion upon the receipt of a call. 
         [0003]    The techniques for dealing with these devices fall generally into two categories namely; a percussive technique which uses a transducer of some type to generate a shock wave which can trigger the device, the percussive type also including devices having parts designed for actual contact with the explosive device, and an electronic type which uses various electronic techniques for both finding and remotely detonating an explosive. 
         [0004]    U.S. Pat. No. 6,487,950 issued to one Samland discloses a method of detecting and detonating land mines using microwave power at a first level for detection and a second level for detonation. While this method may be satisfactory for detonating passive condition responsive buried land mines, it does not address the issue of radio activated IEDs at all and thus cannot be used for that purpose. 
         [0005]    U.S. Pat. No. 7,000,546 issued to Bender et al. Discloses a method of and device for detonating magnetic field responsive sea mines by generating a broad spectrum magnetic field extending about the perimeter of the vessel containing the device. Again, this device is only useful for detonating passive mine assemblies. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention concerns a system and apparatus for detecting and neutralizing remotely activated explosive devices in a combat zone, especially one of relatively limited geographic area such as an urban setting. The apparatus is configured for mounting on or within an airborne drone and includes both transmitting and receiving circuits and antennas. The apparatus detects radio transmissions by analyzing received signals using standard RF direction finding techniques and a spectrum analyzer or other signal processing circuitry. Signals may be classified as threats using predetermined criteria, and the direction of threat signals may be assessed to allow for a determination of an enemy position from which an explosive is to be detonated. The apparatus also transmits a jamming signal which may serve to detonate devices within the dynamic RF footprint of the transmitting antenna. The drone also includes a highly directional low frequency audio device which is periodically directed randomly and at suspected enemy positions. A plurality of drones deployed within a given geographical area may transmit data to a base station, which can then transmit positional data in real time, which in combination with stored data may be used to optimize operational efficiency of the apparatus and allow for planning and altering troop movements. 
         [0007]    In accordance with the above, it is an object of the invention to provide a system and apparatus for detecting and neutralizing remotely activated explosive devices in a combat zone. 
         [0008]    It is another object of the invention to provide a system and apparatus for detecting and neutralizing remotely activated explosive devices in a combat zone having both transmitting and receiving circuits. 
         [0009]    It is another object of the invention to provide a system and apparatus for detecting and neutralizing remotely activated explosive devices in a combat zone having one or more antennas configured for transmitting and receiving RF signals in accordance with the method of the invention. 
         [0010]    It is another object of the invention to provide a system and apparatus for detecting and neutralizing remotely activated explosive devices which employs a remotely controlled and/or programmable drone aircraft. 
         [0011]    It is another object of the invention to provide a system and apparatus for detecting and neutralizing remotely activated explosive devices in a combat zone which employs acoustic means to detonate explosive devices and disrupt enemy positions. 
         [0012]    These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0013]      FIG. 1  is a side view of an apparatus for electronic and acoustic explosive detection and neutralization formed in accordance with the technique of the invention positioned on a drone aircraft. 
           [0014]      FIG. 2  is a side view, partly in cross section of the audio transducer portion of the apparatus. 
           [0015]      FIG. 3  is a side view of an antenna used with the RF receiving and transmitting portion of the apparatus. 
           [0016]      FIG. 4  is an alternative embodiment of the audio transducer portion of the apparatus. 
           [0017]      FIG. 5  is a side view of one quadrant showing a three-antenna arrangement. 
           [0018]      FIG. 6  is a top view showing an alternate embodiment of an antenna arrangement for the apparatus. 
           [0019]      FIG. 7A  is a simulation of an aerial view of a scenario where the system of the invention is deployed. 
           [0020]      FIG. 7B  is a plan view of a scenario where the system of the invention is deployed. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]    Referring now to  FIGS. 1-7B , a system for detecting and neutralizing concealed explosive devices positioned in a combat zone, is shown. The system, generally indicated by the numeral  10 , is configured for use in a wartime environment, and particularly an urban setting. The apparatus used with the system  10  is configured to detect, neutralize, and/or destroy various types of explosive devices as may be deployed ay an enemy in a warfare scenario, and is particularly useful against the so called improvised explosive devices or IEDs, the weapon of choice for enemy soldiers and terrorists engaged in war with traditional standing or occupying armed forces. The system  10  may also be deployed to defeat traditional hidden explosive devices such as land mines. 
         [0022]    Of particular concern for armies dealing with guerilla activities is the remotely controlled IED which may be hidden virtually anywhere but is most often used on or near roads to disrupt troop movements and discourage the normal functioning of a large urban area. These IEDs are especially difficult to neutralize because they are often hidden in other vehicles and may be detonated by a simple RF transmitter or even a cell phone. The apparatus  10  may be divided into two sections, operated in accordance with the system of the invention to detect, neutralize, and destroy all explosive devices of the condition responsive or remotely activated type. Preferably, the system  10  includes electronic and electrical systems mounted on a remotely controlled drone  12  such as a remotely controlled helicopter, but may alternatively be operated on an armored vehicle which may optionally be manned. The advantage of a drone aircraft  12  is that the device is not as susceptible to damage from the explosive devices regardless of whether it finds them or not. Also, the drone  12  can be operated only a few feet above the road surface unlike traditional drones which are operated high above the target area and thus incapable of employing all of the techniques of the invention. Also, the RF footprint of the drone  12  can be kept small so as not to interfere with normal, e.g., cell phone communications, within the target community. 
         [0023]    In accordance with a key aspect of the invention, real time and stored data from past and current deployments of the drones  12  is used to control, and alter as necessary, the operation of the various sub-components of the drone  12 , and to plan and/or alter routes taken by convoys using the drones  12  as will be explained in more detail later. 
         [0024]    Referring now particularly to  FIG. 1 , the first section of the electronic systems mounted on the drone  12  is the RF transmitting/receiving section which consists of an electronic transmitter and receiver circuit section  14 , the transmitting/receiving section  14  operably connected to transmitting and receiving antennas. The transmitting/receiving section  14  is preferably digital and programmable in order to more efficiently coordinate with the various other aspects of the system  10  as will be described in more detail below. The transmitter/receiver circuit  14  should have separate outputs for the transmitting and receiving antennas. Transmitting antenna  100  consists of a primary transmitting element  102  which receives an output directly from the transmitter section of the transmitter/receiver circuit  14 . A parabolic reflector  104  focuses the output of the element into a narrow beam to create a relatively narrow footprint to allow for linear movement of the drone  12 , combined optionally with side to side sweeping movement of the antenna to scan an area having a width slightly wider than e.g., a road to be swept for IEDs. Movement of the antenna  100 , which may be accomplished by a small microprocessor controlled motor  18  attached thereto, may be done under program control to allow for adjusting the area scanned particularly the width of the scan pattern. The electronic counter measure signal emitted from the transmitting/receiving section  14  is frequency shifted in accordance with an adjustable predetermined algorithm to ensure that any IEDs in the area of the scan are irradiated with a signal approximating a detonation signal. The changing frequencies are designed to both detonate and/or interrupt detonation signals intended for the IED. Preferably, at least one microprocessor device  41  is used to coordinate the various electronic systems of the invention, the microprocessor  41  capable of transmitting operational data as well as receiving and storing data associated with previous and current movements of all drones  12  deployed within a given geographical area as will be described in more detail below. 
         [0025]    The receiving antenna  200  is of the direction finding type and may be formed of several elements as is known in the art. As shown in  FIGS. 5 and 6 , the antenna  200  has four groups of three dipole elements  204 ,  206 , and  208  radially spaced and positioned within a housing  209  having terminals  210  for electrical connection to the receiving circuit  14 . The dipole elements  204 ,  206 , and  208  are of varying lengths and arranged from shortest to longest. An isolation reflector  202  extends lengthwise within the housing  209  and has four sides with concave surfaces for isolating the antenna groups. 
         [0026]    Referring now to  FIG. 2 , second section of the apparatus  10  is the sonic disrupter  20  which uses a high powered low frequency audio pulse to detonate land mines. The energy of the audio pulse is sufficient to detonate pressure or impact triggered explosive devices as is known in the art. The disrupter  20  is housed within a cylindrical muzzle  22  which contains a pressure diaphragm  24  capable of withstanding four atmospheric pressures. Compressed air or nonflammable gas is forced into compressed air or nonflammable gas chamber  34  from a source of compressed air or nonflammable gas contained within canister  36  through the compressed air or nonflammable gas line  32  and through the compressed air or nonflammable gas control valve  35 . When the compressed air or nonflammable gas pressure in the compressed air or nonflammable gas chamber reaches three atmospheric pressures, the compressed air or nonflammable gas control valve  35  closes. At this point, the disruptor  20 , is armed for firing. 
         [0027]    Firing of the audio sound blast cannon, device  20 , is initiated by applying power to the plunger shaft release trigger solenoid  56  and pulling the plunger shaft release trigger  54  pulled away from the plunger shaft stopper  50 . At this point the plunger spring  42 , with the assistance of the plunger shaft thrust solenoid  46  as power is applied over the plunger shaft solenoid control wires  60 , accelerate the plunger  40  to sufficient speed to overcome the restraining force of the pressure diaphragm  24  forcing the compressed air or nonflammable gas out the muzzle  22 . The plunger motor/gears  44  drive the plunger shaft  48  rearward to be locked into the firing position by the plunger shaft release trigger  54  locking onto the plunger shaft stopper  50 . The plunger shaft trigger release spring  52  holds the plunger shaft release trigger  54  in place. Once the plunger shaft  48  is locked in place, the plunger motor/gear  44  is lifted slightly, clearing the plunger shaft gears and allowing the plunger shaft  48  to slide forward unimpeded. Concurrent with this action, a secondary pressure diaphragm  26  is automatically placed in the cannon muzzle  22 . 
         [0028]    Information gathered from drones  12  operated in a given area can be transmitted in network fashion to continually indicate to a base station, as well as all troops deploying the drones, of actual or potential enemy IED deployment, thus several drones  12  operated by a plurality of troop convoys can provide real time troop data to enhance transport safety. Referring now specifically to  FIGS. 7A  and B, a typical scenario involving two drones  12  and two accompanying convoys which will include a lead vehicle  33  and optionally additional vehicles  43 . The lead vehicle  33  will include control means  80  for programming and real time control of the drone  12  preferably in the form of a laptop computer  80  with pre-loaded software and a transmitting/receiving antenna  82  connected thereto. The control means  80  software may include GPS data, local map information, etc. as required to provide a two dimensional map or grid from which the operator of the drone  12  can assess the relative positions of threats, other drones  12 , topography, etc., as needed to navigate a preferred route and effect course changes as needed. It should be noted that the drones  12  are pre-programmed with a set of default instructions, stored on microprocessor  41 , for operating the various sub-components as described above, which instructions may be readily modified by control means  80  in accordance with the deployment conditions. Additionally, the control means  80  may include a menu driven software interface which forces the operator to select the various parameters such as detonation signal frequency and scan area upon initialization to ensure optimal deployment of the drone  12 . As the convoys  33 ,  43  proceed, real time information is transmitted to the base station  31  which correlates the data from each convoy  33 ,  43  and transmits data received from all convoys  33 ,  43  so that the information is stored and displayable in a useful fashion on all computers  80 . The base station  31  includes a computer  84  having an antenna  86  operatively connected thereto for receiving data from the convoys  33 ,  43 . The data received from all of the convoys  33 ,  43  is stored on the base computer  84 , the combined data then broadcasted from the base computer via antenna  86 , where it can be displayed on all control means  80  in a useful format. If, for example, a “bogey”  37 ,  38  (e.g., anti-personnel mine, land mine, IED, etc.) is detected, data concerning the bogey  37  such as position, whether or not detonated, frequency of detonation, etc. is transmitted back to the base station  31  (either automatically by drone  12  or by an operator entering data at the control means  80 ) and re-transmitted to all control means  80  currently operating to allow the user (e.g., the driver of a lead vehicle  33 ) to effect course changes etc. as needed. By way of an example, if convoys  33 ,  43  are proceeding along roads A and B without incident, then the portions of roads A and B traversed may be indicated as clear on all active control means  80  for subsequent convoys  33 ,  43 . Data concerning cross roads C and D may have been already transmitted to the base station  31  by previous convoys  33 ,  43  so that the current convoys  33 ,  43  can have information useful should an immediate course change be needed. 
         [0029]    The data obtained at the base station  31  may also be correlated to allow for a determination of terrorist  39  position, e.g., activity centered around a given position. It should be noted that some data, particularly detonation of bogeys  37 ,  38 , or visual confirmation of enemy position will have to be manually entered into control means  80  before it can be transmitted to the base station  31 . Other data such as RF signals transmitted from the drones  12  in response to a threat condition and received by the receiving antenna  82  is automatically stored on control means  80 , where it may be transmitted to the base station  31  for further analysis. 
         [0030]    In an alternative embodiment of the disruptor  20  a volatile fuel system is used for activating the plunger to expel the compressed air  34 . Compressed air must be used with this system. A quantity of fuel is contained within a container  62 . When the plunger  40  and plunger shaft  48  are moved to its cocking position, fuel is passed through the fuel spray nozzle  66  into the fuel chamber  68  behind the plunger. When the system is ready to fire, the trigger solenoid  56  is activated approximately 0.10 seconds prior to the fuel igniter  70  system being initiated. This will allow the plunger  40  and the plunger shaft  48  to move unimpeded. The fuel igniter  70  is then activated and the fuel is ignited causing the plunger  40  to press forward moving the compressed air  34  to expel it at sonic speed towards its objective. As the plunger is returned to the cocking position and the plunger shaft stopper  50  is latched by the plunger shaft release trigger  54 , a one-way spent fuel exhaust valve  72  is opened to release spent fuel. This exhaust valve  72  is closed before the injecting of raw fuel into the firing chamber  68 . After the compressed air is forced into the compressed air chamber  34  to approximately three atmospheres, through the compressed air inlet valve  28 , the compressed air control valve  30  closes. As this action is completed, air is forced into the firing chamber  68  by way of the compressed air distributor  78 , the compression check valve and  74 , and the air injection nozzle  76 . The compression check valve  74  closes to obtain a compression ration of approximately 11 to 1. All other action is identical to the spring firing system. 
         [0031]    An alternative embodiment of the frequency directional finding antenna system device  200  may consist of four each, quadrant located, siamesed antennas consisting of three independently tuned dipole antennas with a isolation reflector. Each antenna wavelength may be tuned to a low frequency band  204 , mid frequency band  206 , and a high frequency band  208 . These bands will be the expected frequencies that would be a compilation of frequencies nominally used for remotely controlled bombs and bomb detonators. The isolation reflector  202  would be designed to minimize interference to the other independent antenna systems. The four antenna systems may be contained within a nonconductive material. The antennas will be connected to the transmitter receiver section  14  which may optionally contain independent frequency analyzers for each antenna group and signal strength electronics thereby providing a general direction from which a suspected frequency is being generated. This information will then be processed by the transmitter receiver section  14  to aid in further defining the suspected frequency location. 
         [0032]    In operation, the drone  12  is released by the user, e.g., a soldier in convoy lead vehicle  33  traversing a combat zone with a high risk of hidden IEDs etc. The drone  12  will sweep a predetermined area as programmed by the user, the area typically being linear and overlapping the intended route. For example, If the road is 25 meters wide, transmitting antenna  100  is oscillated so as to sweep an area 30 meters wide as the drone progresses linearly approximately centrally of the road. The oscillation rate of the antenna  100  would be selected and perhaps modified based upon response time and other parameters as would become apparent depending upon effectiveness over time. The detonation signals broadcast by the transmitting antenna  100  may be narrowed down by intelligence gathered at the base station  31  and broadcast to all the drones  12  to ensure a more effective scan (i.e., to more reliably detonate devices within the scan area of the transmitting antenna) and to reduce the amount of time the directional RF beam is focused on a particular area to allow for a quicker scan and faster troop movement. Receiving antenna  200  will receive and transmitter/receiver circuitry  14  process local RF transmissions to determine the direction and intensity of RF transmissions which may be intended to detonate an IED. Transmitter/receiver circuitry  14  on the drone  12  can adaptively change the RF jamming signal transmitted by antenna  100  in response to a received threat so that a broadband jamming signal is not mandated, and also to minimize unintended interference with local (non threat) RF signals. The information obtained from receiving antenna  200  can then be used to assess potential enemy positions, by e.g. triangulation or other well known techniques. Sonic disrupter  20  is also swept over the target area in much the same pattern as the transmitting antenna to detonate any hidden sub surface IEDs such as mines. All threats encountered by drone  12 /convoy  33 ,  43  are noted by the drone  12  operator and entered into the system using device  80 , for transmission back to the base station  31 , so that the data gathered from all drones  12  deployed over a period of time can be used to assess enemy positions and plan convoy  33 ,  43  routes. Thus, the drones  12  used in accordance with the system can be used to gather data which, as previously mentioned, can be transmitted to the base station  31  which includes data processing means  84  for storing and coordinating threat data. The combined threat data obtained from all previously and currently active drones  12  can then be continuously transmitted from the base station  31  to control means  80  so that any active drone  12  can access all current and previous data.