Abstract:
The invention provides a system and method for reducing the instance of friendly fire by having the weapon aiming system include means for emitting an optical signal encoded with the identity of the targeting soldier. The encoded optical signal is received by an optical receiver on a targeted soldier where it is converted into a low power RF signal which is transmitted to a local repeater that retransmits it, optionally using at least one intermediate repeater, to a central monitoring station equipped with a computerized database. If the monitoring station determines that the doubly encoded signal includes the identities of two friendly troops, it transmits a “hold fire” signal back to the aiming system, and a suitable signal, such as a red LED indicative of a “hold fire” order is illuminated.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a method and apparatus for diminishing incidences of “friendly fire”. In particular, the invention relates to a covert device which can be used to identify and locate friendly forces in order to reduce the likelihood that they will be subjected to “friendly fire” 
     Military personnel use weapons, such as rifles, in combat. Heretofore, there have been numerous “friendly fire” instances in which friendly forces have been targeted, often with tragic results. Obviously, it would be highly desirable to avoid targeting and engaging friendly forces. However, heretofore, that has not always been possible due to miscommunications, or lack of communication, as to the locations of non-hostile forces. Accordingly, their engagement, in the mistaken belief that they were hostile has had tragic consequences. 
     While devices have, heretofore, been employed to provide means for identifying aircraft, including so-called “IFF” (Identification Friend of Foe) encoded transponders, such devices are too bulky to be carried on individual soldiers. Further, as such devices include both radio receivers (which must always remain active) and radio transmitters (which broadcast responses), their use on individual foot soldiers would require an ongoing supply of power. 
     Thus, while personal devices have been developed for use in games and for training military personnel, the operation of such devices have relied upon the fact that they would be used for only limited times, whereby battery power supplies could be used, with recharging between use. Thus, by way of example, so-called “laser tag” devices have been developed. “Laser Tag” is a team or individual sport where players attempt to score points by engaging targets, typically with a hand-held infrared-emitting targeting device. Infrared-sensitive targets are commonly worn by each player and are sometimes integrated within the arena in which the game is played. Although the name implies the use of lasers, real lasers are generally not used except as aiming devices. The actual transmitting element of almost all laser tag gear is an infrared Light Emitting Diode similar to those used in household remote controls. The computerized targeting device wielded by a player commonly emits a brief infrared beam which carries an identifying signal, and the target(s) record the signal when they are hit by the beam. In many cases, the targeting device also houses a visible laser to assist the player in aiming. 
     A known variation of laser tag, called Multiple Integrated Laser Engagement System or “MILES” has been used by the United States Armed Forces and other armed forces around the world for training purposes. MILES uses lasers and blank cartridges to simulate actual battle. Individual soldiers carry small laser receivers scattered over their bodies, which detect when the soldier has been illuminated (i.e., “fired upon”) by a hostile soldiers firearm&#39;s laser. In MILES each laser transmitter is set to mimic the effective range of the weapon on which it is used. 
     Different versions of MILES systems are available both within the US and internationally. The capabilities of the individual systems can vary significantly but in general all modern systems carry information about the shooter, weapon and ammunition in the laser. When this information is received by the target, the target&#39;s MILES system determines the result of the “hit” using a random number roll and a table lookup. As a result a MILES emulating an M-16 rifle cannot destroy an Armored Personnel Carrier (APC), but could still kill a commander visible in the hatch of the vehicle. Vehicles are typically outfitted with a belt of laser sensors while dismounted troops often wear a vest or harness with sensors as well as a “halo” of sensors on their helmets. Often these MILES systems are coupled with a real-time data link allowing position and event data to be transmitted back to a central site for data collection and display. More sophisticated systems for tanks and APCs exist that use various techniques (including scanning lasers and coupled radio systems) to allow more precise targeting of armored vehicles. 
     Problems with adaptations of the MILES system for use in preventing actual friendly fire instances relate to the size and power restrictions required by MILES systems. 
     SUMMARY OF THE INVENTION 
     A method and apparatus for reducing the instances of “friendly fire” includes the use of an optical sensor which is able to detect a beam emitted by an optical illuminator. Upon detection of a suitable signal, which may be selectively encoded, the illuminated sensor sends a signal encoded with identifying data, to a central station, possibly using an airborne relay, where the identifications of both the soldier who has engaged the potential target and the potential target are made, whereby the central station can communicate that the potential target is a “friendly” who should not be engaged. Manned or unmanned airborne units may be used to relay communications, or an airborne unit may be used to house the central station. 
     In a preferred embodiment of the invention, the system is comprised of a rifle sight, such as telescopic sight, and the optical illuminator includes an emitter built into and aligned with the telescopic sight (or “scope”). The optical emitter is preferably an infrared emitter, whereby its beam cannot be seen. In a preferred embodiment, circuitry contained in the scope and associated with the optical emitter encodes the emitted optical beam with a code unique to each emitter. The circuitry associated with the emitter preferably includes also a radio receiver and means, such as LEDs which can be seen by the user of the scope, whereby a “go”/“no go” signal can be seen while sighting the weapon through the scope. 
     In accordance with the invention, optical sensors on troops include circuit means for receiving and decoding optical signals from the scope mounted optical emitters. The circuitry associated with the optical sensors includes a GPS locator and a transmitter which transmits the location of the receiver to a “central” monitoring station, which can include an airborne unit. The central monitoring station is able to decode the received signal and then transmit a signal to the targeting soldier&#39;s weapon, whereby the targeting soldier will receive a “no go” signal if the target is part of a friendly force. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       In the Drawing: 
         FIG. 1  is a perspective view of a telescopic sight of the type used with the present invention; 
         FIG. 2  is a block diagram of the electronics associated with the telescopic sight of  FIG. 1 ; 
         FIG. 3  is a block diagram of the electronics associated with the optical receiver RF encoder and transmitter worn by a soldier; 
         FIG. 4  is a block diagram of the local repeater used with the optical receiver RF encoder and transmitter of  FIG. 3 ; 
         FIG. 5  is a pictorial diagram illustrating the operation of the invention; and 
         FIG. 6  is a flow chart illustrating the manner in which the inventive method works. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Instances of “friendly fire”, in which non-hostile military personnel are targeted and engaged, should be avoided. Heretofore, that has not always been possible due to miscommunications, or lack of communication, as to the locations of non-hostile forces. Accordingly, their engagement, in the mistaken belief that they were hostile has had tragic consequences. 
     While devices have, heretofore, been employed to provide means for identifying aircraft, including so-called “IFF” (Identification Friend of Foe) encoded transponders, such devices are too bulky to be carried on individual soldiers. Further, as such devices include both radio receivers (which must always remain active) and radio transmitters (which broadcast responses), their use on individual foot soldiers would require an ongoing supply of power. Thus, existing laser tag or MILES systems cannot be adapted for use in the manner needed to enable them to be used for the present purposes. Further, as such prior systems included limitations relating to the capabilities of the emulated weaponry, in true combat situations their use would be limited. 
     Referring to  FIG. 1 , in accordance with the present invention, a weapon, such as a rifle (not shown) is fitted with an aiming device, such as telescopic sight (or “scope”)  10 . The scope  10  is fitted with one or more optical emitting devices  12  which are used to emit an optical beam which is preferably in the infra-red spectrum, whereby it cannot be readily observed by people. As will be explained below, in the preferred embodiment of the invention, the beam transmitted by the optical emitting device  12  is encoded with an identification signal which identifies the soldier who is using the scope  10 . A pushbutton  14  on the scope  10  selectively energizes the optical emitter  12  using a circuit  16  built into a housing  18  on the scope  10 . 
     Referring to  FIG. 2 , a block diagram of the circuit  16  built into the scope  10  ( FIG. 1 ) and associated with the optical emitter  12  and the pushbutton switch  14  is shown. In accordance with the invention the circuit  16  includes a programmable microcontroller  20  and a power supply  22 , which may be comprised of button type cells. The circuit  16  also includes a receiver  24  which is connected to an antenna  26  mounted on the scope  10 . A light emitter, such as a red LED  28  is mounted such that it can be seen by a soldier using the scope  10 . By way of example it may be mounted on the scope  10  with circuit  16 , with an opening formed which allows light from the LED  28  to be seen within the scope  10 . When the soldier using the scope  10  engages a target and presses the pushbutton  14  the optical emitter  12  transmits an encoded optical signal which is aligned with the scope  10 . The encoded optical signal is encoded with the identification of the targeting soldier. 
     With reference to  FIG. 3 , a receptor circuit  30  worn by friendly forces includes an optical sensor  32  and a short range radio frequency transmitter  34  which is designed to have a very low power drain until it is energized by optical detection circuitry  36 . When the optical sensor  32  detects an illuminating signal (e.g., from the circuit  16  mounted on the scope  10 ), the transmitter  34  is energized, and it retransmits the encoded optical signal (as detected) to a nearby local repeater device  40  using antenna  42 . 
     Referring now to  FIG. 4 , a block diagram of the local repeater  40  is shown. As illustrated, the local repeater  40  which preferably includes a receiver  42 , which uses an antenna  44  to receive signals from nearby circuits  16 . The received signals are processed by receiver circuitry  46 , and then transmitted by transmitter  48  using antenna  50 . 
     Referring now to  FIG. 5  and  FIG. 6 , an overview of the operation of the invention is illustrated in  FIG. 5 , with a block diagram of the method illustrated in  FIG. 6 . As shown, when a soldier  50  aims at a friendly soldier  52 , and the soldier presses the button  14  on the scope  10  on his rifle, an encoded infrared beam is emitted by the emitter  12  on the scope  10  and the encoded optical beam is picked up by the sensor  32  on the soldier  52 , causing the associated electronic unit  30  on the soldier  52  to convert the optically encoded signal into a radio frequency (“RF”) signals which is transmitted by transmitter  34  on the soldier  52 . That RF signal is picked up by local repeater  40  which retransmits it. The retransmitted signal from local repeater  40  is picked up by suitable means, such as by an unmanned aerial vehicle (“UAV”)  54 . The UAV is able to relay the encoded signal back to a central monitoring station  56  at which the encoded signal, which has been encoded with identification information from both soldiers  50 ,  52 , is decoded. The central monitoring station  56  uses the decoded signal to determine the identities of the soldiers  50 ,  52  using a database  58  associated with a computer  60 . If they are both “friendlies”, the central monitoring station  56  transmits a “hold fire” signal, which can be relayed by the UAV  54  back to the circuit  16  in the scope  10 , whereby the circuit  16  will immediately cause the “hold fire” LED  28  in the scope  10  to light up, thereby identifying the targeted soldier  52  as a friendly who should not be fired upon. 
     The foregoing steps of the present inventive method are illustrated in the block diagram  70  in  FIG. 6 , in which the soldier  50  targets soldier  52  and presses button  14  at  72 . This causes an optical signal, encoded with the identity of soldier  50  to be emitted by emitter  12  at step  74 . At step  76 , the encoded optical signal is received by circuit  36  on soldier  52 , and it is retransmitted as an RF signal which has been further encoded with the identity of soldier  52 , whereby the RF signal includes encoded identification of both soldiers  50 ,  52 . At step  78  the doubly encoded signal is received by local repeater  40 , which retransmits it. The retransmitted signal is received by UAV  54  which retransmits it to the central monitoring station  56  at step  80 . The a computer  60  within the central monitoring station  56  performs a lookup of the encoded identities of the soldiers  50 ,  52  in database  58  at step  82 , and if the lookup shows that both soldiers  50 ,  52  are “friendly”, then a “hold fire” signal is transmitted back to UAV  54  which retransmits it to the circuitry  16  in the scope  10  of soldier  50  at steps  84 ,  86 , where the circuitry  16  causes the “hold fire” LED  28  in the scope  10  to alert soldier  50  that he should not fire on friendly soldier  52  at step  88 . 
     In a preferred embodiment of the invention, the local repeater  40  further encodes the signal sent to the UAV  54  with a location signal, such as one derived by a GPS receiver within the local repeater  40 , whereby the monitoring station  56  can be updated with the location of soldier  52 . Also, if the monitoring station  56  is aware of the general location of soldier  50 , e.g., that he is in the general location of soldier  52 , then the monitoring station  56  can be more selective about the UAV or other repeater means which it uses to transmit the “hold fire” signal to soldier  50 . 
     While the invention has been described with reference to a preferred embodiment, those skilled in the art will recognize that the UAV  54  which acts as an intermediate repeater could be replaced by a manned aircraft, a low earth orbit satellite, or a repeater on a hill or other suitable area. If the area occupied by the local repeater is sufficiently close to the central monitoring station, or if RF conditions are appropriate, it may be possible to avoid the use of an intermediate repeater to send the signal to the central monitoring station, although it would generally be best to have an intermediate repeater send the “hold fire” signal from the central monitoring station  56  back to the soldier  50  to insure that it is received, although depending on frequency, atmospherics, and distance, it may be possible to avoid an intermediate repeater in sending the “hold fire” signal, as well. 
     As will be obvious to those skilled in the art, the present invention has been described in a preferred embodiment which is to be limited solely by the scope of the claims herein.