Patent Publication Number: US-2011059421-A1

Title: Apparatus and method for automated feedback and dynamic correction of a weapon system

Description:
FIELD OF THE INVENTION 
     This invention relates to targeting of the weapon systems generally, and specifically to adjusting targeting solutions of weapon systems based on location notifications about projectiles fired by weapon systems. 
     BACKGROUND 
     Weapon systems, such as mortars and artillery pieces, are widely used by military forces worldwide. The weapon systems are used to fire projectiles, such as artillery shells or mortar rounds, at a target. Once fired, the projectile flies toward the target and lands at an impact location. The projectile may carry a payload designed to explode upon impact. Upon impact, the projectile may use concussive and explosive forces to further injure and/or destroy the target. Some projectiles also carry fragments of metal, ceramic or other materials to injure or destroy the target. The projectile may destroy the target if the impact location of the projectile is within a “lethal radius”, or close enough to destroy the target. The projectile may injure or partially destroy the target, such as when the target is near, but not within, the lethal radius. 
     There are many reasons to reduce the number of targeting adjustments and therefore the number of projectiles fired at the target. Current weapon systems, though generally accurate, require targeting adjustments to land projectiles within the lethal radius of the target. To verify a targeting adjustment is accurate, at least one projectile must be fired at the target. Firing projectiles may be expensive, as each projectile may cost hundreds or even thousands of dollars. Further, firing even one projectile from a weapon system may damage people and property not at the targeted location. The location of a weapon system may be given away after firing a projectile, possibly leading to an attack, such as counter-battery fire, that harms or kills the users of the weapon system as well as the weapon system. 
     SUMMARY 
     Embodiments of the present application include methods and apparatus for adjusting a targeting solution of a weapon system using location notifications received about projectiles fired by the weapon system. 
     A first embodiment of the invention provides a method for adjusting a targeting solution of a weapon system. The weapon system fires a first projectile at a target. A first location notification is received about the first projectile. The first projectile includes a location device. A first impact location of the first projectile is determined based on the first location notification. The targeting solution of the weapon system is adjusted based on the determined first impact location. 
     A second embodiment of the invention provides a projectile-tracking device. The projectile-tracking device includes a processor, data storage, and machine-language instructions stored in the data storage. The machine-language instructions are executable by the processor to perform functions including: (i) determining a first target of a first weapon system, (ii) receiving a location notification from a projectile fired from the first weapon system, (iii) determining a first impact location of the projectile, and (iv) determining a second target of the first weapon system based on the first impact location. 
     A third embodiment of the invention provides a system. The system includes a weapon system and a projectile-tracking device. The weapon system is configured to fire a projectile at a target. The projectile includes a location device. The projectile is configured to send a location notification. The projectile-tracking device is configured to (i) receive the location notification and (ii) display a projectile-status display. The projectile-status display includes: the location of the projectile based on the received location notification, a location of the weapon system, and the target of the weapon system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various examples of embodiments are described herein with reference to the following drawings, wherein like numerals denote like entities, in which: 
         FIGS. 1A and 1B  are block diagrams of a side view and a top view, respectively, of an example of a weapon system, in accordance with embodiments of the invention; 
         FIG. 2  is a depiction of an example weapon system firing a projectile at a target, in accordance with embodiments of the invention; 
         FIG. 3  shows an example of a projectile, in accordance with embodiments of the invention; 
         FIG. 4  shows an example scenario with a projectile-tracking device tracking a plurality of the projectiles fired by a plurality of the weapon systems at a plurality of targets, in accordance with embodiments of the invention; 
         FIG. 5  shows an example projectile-status display of a projectile-tracking device, in accordance with embodiments of the invention; 
         FIG. 6  is a block diagram of an example computing device, in accordance with embodiments of the invention; 
         FIG. 7  is a schematic view of an example location notification, in accordance with embodiments of the invention; and 
         FIG. 8  is a flowchart of an example method, in accordance with embodiments of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     The instant application describes use of location notifications received about projectiles to adjust a targeting solution of a weapon system. A location notification is an indication of a location of the projectile after being fired from the weapon system. A location notification may indicate an in-flight location or an impact location of the projectile. An in-flight location of a projectile is a location of the projectile between the time when the flight of the projectile begins (e.g., when the projectile is fired) and the time when the flight of the projectile ends (e.g., when the projectile lands). An impact location of a projectile is a location where the flight of the projectile ends. One or more location notifications may be received by a projectile-tracking device about an in-flight location and/or an impact location of the projectile. 
     To determine a location notification, a projectile to be fired by the weapon system may comprise a location device. The location device may be “active” and send location notifications or be “passive” and allow a device, such as a range-finding device, to send location notifications based on passive location device observations made by the range-finding device. 
     The projectile-tracking device may determine an impact location of the projectile based on the location notification. The determined impact location may be estimated by the projectile-tracking device, based on the ballistics equation of motion and/or curve-fitting algorithms. 
     Information provided by the projectile-tracking device may be used to adjust a “targeting solution” of the weapon system, based on the determined impact location. For example, the projectile-tracking device may directly or indirectly adjust the targeting solution. The projectile-tracking device may directly adjust the targeting solution by changing the targeting solution of the weapon system. The projectile-tracking system may indirectly adjust the targeting solution by displaying information, such as a projectile-status display, to a user of the weapon system for the user to adjust the targeting solution after reviewing the displayed information. 
     Turning to the figures,  FIGS. 1A and 1B  are block diagrams of a side view and a top view, respectively, of a weapon system  100 , in accordance with embodiments of the invention.  FIG. 1A  shows the weapon system  100  with a gun tube  102  having a muzzle  104 , a breech  106 , and a firing mechanism  108 . The weapon system  100  may be used to fire one or more projectiles, such as projectile  110 . A soldier or other user of the weapon system  100  may insert the projectile  110  into the firing mechanism  108 , typically via a door (not shown) in the firing mechanism  108  providing access to the breech  106  of the gun tube  102 . The soldier may fire the weapon system  100  causing the projectile  110  to leave the weapon system  100  via the muzzle  104  to fly along a trajectory. After the projectile  110  flies along the trajectory, the projectile  110  may impact at an impact location. 
     The elevation of a weapon is the angle between a horizontal plane representing the ground and a direction of a gun tube of a weapon system.  FIG. 1A  shows an elevation  180  of E° for the weapon system  100 .  FIG. 1A  depicts the elevation  180  as a dashed line indicating the angle between a horizontal plane  182  running along a bottom of the weapon system  100  and a direction  184  of the gun tube  102  of the weapon system  100 . The elevation may be expressed in angular units such as degrees, radians, or as a quadrant elevation (QE). The QE may be expressed in terms of degrees or “mils” or units of rotation. (There are 6,400 mils of rotation in a circle; for example, a QE of 800 mils corresponds to a 45° angle.) 
     The azimuth indicates a direction of fire for the weapon system (i.e., the direction of the gun tube or barrel of the weapon system) expressed as an angle from a reference plane, such as true north.  FIG. 1B  indicates an azimuth  190  of A°.  FIG. 1B  depicts the azimuth  190  as a dashed line, indicated with respect to a reference plane  192  and a direction of the gun tube  102 . The azimuth may be expressed in angular units such as radians, degrees, or in mils. Another term for the azimuth is a “quadrant direction” (QD), often used when the azimuth is expressed in mils. Note that some weapon systems  100  may not have a gun tube  102 , so the azimuth and elevation may be expressed with reference to a direction of fire or other reference rather than with reference to a gun tube as described herein (i.e., rails for a rail gun). 
       FIG. 2  is a depiction of the example weapon system  100  firing the projectile  210  at a target  220 , in accordance with embodiments of the invention. The weapon system  100  may be aimed at the target  220 , and may fire one or more projectiles, such as the projectile  210 . The projectile  210  is shown in  FIG. 1  with a circular shape. However, the projectile  210  may have a different shape, such as a conical or bullet shape, rather than a circular shape. A targeting solution may be specified to aim the weapon system  100 . 
     The targeting solution may comprise a location of the weapon system  100 , as well as the elevation and the azimuth. The weapon system  100  may be mobile, such as a self-propelled howitzer or gun mounted on a tank. As such, the location of the weapon system  100  may change. In some situations, mobile weapon systems may not choose to change locations; such as when moving a mobile weapon system would draw enemy attention to the weapon system or if movement of the mobile weapon system could harm friendly forces. 
       FIG. 2  shows the weapon system  100 , the projectile  210 , information sources  240 , a projectile-tracking device  250 , and a ballistics engine  260  connected to a network  230 . The weapon system  100  may have a network interface to connect to the network  230 . The network interface of the weapon system  100  may be configured to send and receive data and may include a wired-communication interface and/or a wireless-communication interface. The wired-communication interface, if present, may comprise a wire, cable, fiber-optic link or similar physical connection to a wide area network (WAN), a local area network (LAN), one or more public data networks, such as the Internet, one or more private data networks, or any combination of such networks. The wireless-communication interface, if present, may utilize an air interface, such as an IEEE 802.11 (e.g., Wi-Fi) interface to a WAN, a LAN, one or more public data networks (e.g., the Internet), one or more private data networks, or any combination of public and private data networks. 
     Each data network in the network  230  may be secured using physical and/or cryptographic security of network connections; for example, all network transmissions to and from the weapon system  100  may be encrypted. Securing network connections increases the chance that an enemy will not intercept and/or scramble data on the network connections. Data may be transmitted in an encrypted format for security using cryptographic protocols and/or algorithms, such as DES, AES, RSA, Diffie-Hellman, and/or DSA. Other cryptographic protocols and/or algorithms may be used as well or in addition to those listed herein. If data is sent in an encrypted format, a device receiving the data, such as the weapon system  210  or the projectile-tracking device  250 , may decrypt the data, such as the location information. 
       FIG. 2  shows information sources  240  connected to the network  230 . The information sources  240  may provide information to the projectile-tracking device  250 . For example, information sources  240  may provide meteorological information, tactical and/or strategic information, information about targets and their activities, as well as many other types of information to projectile-tracking device  250 . The projectile-tracking device  250  may integrate and provide information from information sources  240  to a user of the projectile-tracking device  250 . 
     The projectile-tracking device  250  may track one or more projectiles. To track one or more projectiles, the projectile-tracking device  250  may receive location notifications. The location notifications may be sent from a plurality of the projectiles fired from a plurality of the weapon systems at a plurality of targets and/or from one or more range-finding devices. 
     The projectile-tracking device  250  may track profiles by assigning an identifier to each projectile  210 . The projectile-tracking device  250  may assign an identifier to a projectile by: (a) assigning an identifier to each weapon system, (b) maintaining a count of the projectiles fired by the weapon system, and (c) generating the identifier for the projectile based on the assigned identifier for the weapon system and/or the count of the projectiles fired. For example, if the weapon system “WS 3 ” has already fired 4 projectiles, projectile-tracking device  250  may generate an identifier such as “WS 3 - 5 ” for the next (fifth) projectile to be fired by WS 3 . Many other assignment algorithms are possible. 
     The identifier of the projectile may be pre-assigned. For example, a pre-assigned identifier may be painted on the projectile or encoded as a bar code. The bar code may be printed on a sticker that is affixed on the projectile and later read from the sticker, perhaps with a bar code reader. 
     In an embodiment of the invention, an identifier of the projectile is an identifier that can be used for secure communications with the projectile, i.e. the identifier is used a cryptographic key. The use of secure or encrypted communications provides additional security when communicating with the projectile. The cryptographic key may be used to encrypt and/or decrypt communications with the projectile using cryptographic protocols and/or algorithms, such as DES, AES, RSA, Diffie-Hellman, and/or DSA. Other cryptographic protocols and/or algorithms may be used as well or in addition to those listed herein. 
     The projectile-tracking device  250  may receive location notifications from projectiles fired by one or more weapon systems, such as the projectile  210 . Projectile-tracking device  250  may receive a location notification including an in-flight location of the projectile  210  and/or an impact location of the projectile  210 . 
     The projectile-tracking device  250  may determine the impact location based on location information provided by the projectile  210  in one or more location notifications. For example, the projectile  210  may provide the impact location as location information in a location notification. 
     The projectile-tracking device  250  may determine an impact location of the projectile by estimating the impact location of the projectile  210  based on one or more in-flight location notifications from the projectile  210 . For example, the projectile-tracking device  250  may determine a curve (e.g., a parabola) that passes through or passes close to the locations provided by the in-flight notifications using a curve-fitting algorithm. Based on the determined curve, projectile-tracking device  250  may be able to determine an impact location. 
     For example, assume a curve determined by a curve-fitting algorithm is: y(t)=245*t−4.9*t 2 , where y=distance above ground in meters and t=time in seconds. By setting y=0 and solving for t, the projectile-tracking device  250  may determine that t=50 seconds. Further assume that the projectile is traveling at 245 meters/second from the weapon system along the azimuth (i.e., in the direction of fire). Then, after 50 seconds, the projectile-tracking device  250  may determine that the impact location will be 245*50=12,250 meters from the weapon system along the azimuth. 
     The projectile-tracking device  250  may estimate the impact location of the projectile using a mathematical model. For example, the well-known ballistic equation provides a mathematical model of an ideal trajectory of the projectile. NATO Standardization Agreement 4355, which is incorporated herein by reference, provides a detailed mathematical model based on the ballistic equation, for trajectory simulation of artillery projectiles for NATO Naval and Army forces. [NATO Military Agency for Standardization, NATO Standardization Agreement 4355, Subject: The Modified Point Mass Trajectory Mode, p. 1, Revision 2, Document No. MAS/24-LAND/4355, Jan. 20, 1997 (“STANAG 4355”).] 
     Based on projectile location information, including impact locations, the projectile-tracking device  250  may adjust a targeting solution of the weapon system  100 . A targeting solution of the weapon system  100  may comprise the azimuth, the elevation, and/or the location of the weapon system  100 . For example, if a location notification from the projectile  210  indicates that the impact location of the projectile  100  was short of the target  220 , the projectile-tracking device  250  may adjust the elevation of the weapon system  100  to be closer to a possible maximum range angle of 800 mils (45°). Similarly, the projectile-tracking device  250  may adjust the azimuth of the weapon system  100  if a projectile does not impact on or near a direct line from the weapon system to the target. If the weapon system  100  is mobile, the projectile-tracking device  250  may adjust the targeting solution of the weapon system  100  by changing the location of the weapon system  100  (e.g., move the weapon system  100  closer to the target  220 ). The projectile-tracking device  250  may simultaneously adjust any combination of the location, the elevation, and the azimuth of the weapon system  100  in adjusting the targeting solution of the weapon system  100 . 
     The projectile-tracking device  250  may adjust the targeting solution based on previous targeting solutions and/or previous impact locations as well. The weapon system, once targeted, may maintain a previous targeting solution until later adjusted. As such, a targeting solution may depend on the previous targeting solution. 
     The previous targeting solutions and/or previous impact locations may be compared to determine error patterns in the weapon system  100 . For example, suppose a mathematical model using targeting solution t (e.g., the ballistics equations) predicts an impact location would be at a point x. Further suppose the actual impact location of a projectile fired by the weapon system  100  using targeting solution t is at a point x′, where the azimuth of the point x′ is slightly to the left of the predicted impact location x. If this pattern continues; that is, if many or all projectiles fired by weapon system  100  have impact locations slightly to the left of predicted impact locations, the targeting solution may be adjusted to account for this error pattern of the weapon system  100  shooting slightly to the left. Similar adjustments may be made for the elevation and location components of the targeting solution as well. 
     User input may confirm, partially override, or completely override adjustments to the targeting solution provided by the projectile-tracking device  250 . For example, suppose the projectile-tracking device  250  adjusts a targeting solution of the weapon system  100  by attempting to change the elevation and azimuth of the weapon system  100 . A user of the projectile-tracking device  250  may confirm the adjustment to the targeting solution. The user of the projectile-tracking device  250  may also partially override the targeting solution by accepting the attempted change in elevation but not the change in azimuth or vice versa. In another example, suppose projectile-tracking device  250  adjusts a targeting solution of the weapon system  100  by attempting to change the location of the weapon system  100 . The user of the projectile-tracking device  250  may determine movement of the weapon system  100  is unacceptable and completely override an adjustment to the targeting solution that involves changing the location of the weapon system  100 . In an embodiment of the invention, no user input is required to adjust the targeting solution of the weapon system  100  (i.e., the adjustments to the targeting system are fully automatic). 
     User input may provide one or more adjustment ranges that the projectile-tracking device  250  can make to the targeting solution of the weapon system  100 . Intervening objects and/or people may make some targeting solutions invalid; for example, targeting solutions that involve firing shots into a building housing only noncombatants or housing friendly forces are generally invalid. Each one or more adjustment ranges may indicate that the adjustment range is either valid or invalid. 
     The one or more adjustment ranges may be provided to the weapon system  100  via an information source  240 , such as a command, control, communications, and intelligence (C 3 I) information source. The C 3 I information source may indicate to the weapon system  100  that valid targeting solutions are (or are not) within one or more adjustment ranges. The C 3 I information source may also confirm, partially override, or completely override adjustments to the targeting solution provided by the projectile-tracking device  250 . 
     Therefore, the targeting solution may be fixed to permit projectile-tracking device  250  to adjust the targeting solution of the weapon system  100  within a valid adjustment range of elevation values, azimuth values and/or locations of the weapon system  100 . For example, if friendly forces are located south of the weapon system  100 , an adjustment range of elevation, azimuth, and/or location values may prohibit invalid targeting solutions, such as azimuths of 3000-3400 mils from true north (i.e., a range of azimuths south of the weapon system  100 ) may be provided to the projectile-tracking device  250 . 
     The projectile-tracking device  250  may adjust the targeting solution of the weapon system  100  indirectly, such as by displaying information about the targeting solution of the weapon system  100 . After reviewing the displayed information about the targeting solution, a user of the weapon system  100  may then adjust the targeting solution of the weapon system  100 . For example, the projectile-tracking device  250  may display an impact location of the projectile  210  fired by the weapon system  100 . Based on the displayed impact location, a user of the weapon system  100  may adjust the targeting solution of the weapon system  100 . The projectile-tracking device  250  may also display a suggested targeting solution as well (e.g., change elevation from 1000 mils to 980 mils or move the weapon system forward 100 meters). 
     User input may be provided to configure the projectile-tracking device  250  by selecting direct, indirect, or both direct and indirect adjustments to the targeting solution, by specifying adjustment ranges, by requesting a display of suggested targeting solutions, and/or by specifying which parameters of a targeting solution may be adjusted by the projectile-tracking device  250 . 
     The projectile-tracking device  250  may make a series of adjustments to the targeting solution of the weapon system  100  based on multiple impact locations of the projectiles fired by the weapon system  100 . If the weapon system  100  fires a first projectile at the target  220 , the projectile-tracking device  250  may adjust the targeting solution of the weapon system  100 , based on a first impact location of the first projectile. Then, the weapon system  100  may fire a second projectile at the target  220 . The projectile-tracking device  250  may adjust the targeting solution of the weapon system  100  based on a second impact location of the second projectile. The projectile-tracking device  250  may adjust the targeting solution of the weapon system  100  based on multiple impact locations (e.g., both the first impact location and the second impact location). The adjustment of the targeting solution of the weapon system  100  based on multiple impact locations may be repeated as needed (i.e., as long as projectiles are fired at the target  220 ). 
     The projectile-tracking device  250  may suggest other solutions to hit the target beyond adjusting the targeting of the weapon system  100 . For example, projectile-tracking device  250  may use different projectiles with a higher “charge level” or amount of propellant to reach a longer distance if shots fired at the maximum range angle are short. If multiple targets are available, the projectile-tracking device  250  may suggest a targeting solution aimed at a different target if the current target is out of range or otherwise difficult to hit. 
     The projectile-tracking device  250  may determine a lethal radius of the projectile  210 . The lethal radius of the projectile  210  may be determined based on a type and amount of payload carried by the projectile  210 . For example, a projectile carrying a payload with a large amount of high explosive may have a larger lethal radius than a projectile with a smaller payload and/or a less powerful type of explosive. The lethal radius may be determined based on a model of an explosion of a type and amount of payload. The projectile-tracking device  250  may use a lookup table to look up the lethal radius based on the type and amount of payload. The projectile-tracking device  250  may determine the lethal radius based on the construction of target as well; for example, the lethal radius of a concrete building may be smaller than the lethal radius of a wooden shed. 
     The projectile-tracking device  250  may determine a status of the target  220 . The status of the target  220  may be based on the construction of the target  220 , the projectile  210 , and/or one or more impact locations. For example, the status of the target  220  may be based on determining an impact location is within a lethal radius of a target. As described above, the lethal radius may depend on the construction of the target  220  and the payload of the projectile  210 . 
     A categorical status of the target  220  may be determined. The term “deflection” is the distance from the target  220  to an impact location of a projectile fired at the target  220 . For example, if the deflection is within the lethal radius of the projectile  210 , the status of the target  220  may be “destroyed”. If the deflection is near, but not within the lethal radius of the projectile  210 , the status of the target  220  may be “partially destroyed”. If the deflection is not near the lethal radius of the projectile  210 , the status of the target  220  may be “intact” or unchanged. A numerical value may be used for the status of the target as well (e.g., 80% destroyed or 50% intact). 
     The determination of a deflection being “near” the target may be performed by comparing the distance between the target and an impact location to one or more thresholds. The one or more thresholds may be based on the lethal radius. For example, a first threshold of a deflection being “near” the target may be two times the lethal radius, and a second threshold of a deflection being “far” from the target may be four times the lethal radius. In this example, if the deflection is within the lethal radius, the status of the target may be “destroyed”; if the deflection is “near” or outside the lethal radius but close to the first threshold, the status of the target may be “nearly destroyed”; if the deflection is between the first and second thresholds, the status of the target may be “partially destroyed”; otherwise, the deflection is “not near” and thus the status of the target is unchanged. The status of the target may be adjusted based on multiple impact locations as well; e.g., if a target has been nearly hit by multiple projectiles, the status of the target may be adjusted from “partially destroyed” to “nearly destroyed”. 
     The projectile-tracking device  250  may adjust the targeting solution of the weapon system  100  to fire at a different target based on an impact location of a projectile. For example, if the impact location of a projectile is within a lethal radius of a projectile, the projectile-tracking device  250  may determine that the status of the target  220  is nearly or completely destroyed. After determining the status of the target  220  to be nearly or completely destroyed, the projectile-tracking device  250  may determine that the weapon system  100  is to be aimed at and then fired at a different target. The projectile-tracking device  250  may accept user input to confirm or override an adjustment of the weapon system  100  to aim at and/or fire at a different target. 
     The projectile-tracking device  250  may determine that no more projectiles are to be fired at the target  220 . For example, the projectile-tracking device  250  may determine that no more projectiles are to be fired if (a) no more targets are available to the weapon system  100  (i.e., all targets have been destroyed or are out of range of the weapon system  100 ), (b) no more projectiles are available for the weapon system  100  to fire, and/or (c) based on user input to the projectile-tracking device  250 . 
       FIG. 2  shows the weapon system  100  connected via the network  230  to ballistics engine  260 . An example ballistics engine  260  is described in the U.S. patent application Ser. No. ______, entitled “Method and Apparatus for Analysis of Errors, Accuracy, and Precision of Fire Control Mechanisms”, Honeywell Docket No. H0018175-5548, filed on ______, which is incorporated herein by reference. 
     The ballistics engine  260  may simulate the performance of the weapon system  100 , such as determining simulated trajectories and/or impact locations of shots fired by the weapon system  100 . Based on simulated shots of the weapon system  100 , the ballistics engine  260  may determine performance results of the weapon system  100 , such as an analyzed-impact-location graph comprising mean point of impact, standard deviation, and center error probable information. The projectile-tracking device  250  may adjust the targeting solution of the weapon system  100  based on information from the ballistics engine  260 , including simulated impact locations, simulated trajectory information, statistical results, and/or the error-weighting function of the weapon system  100 . 
     The ballistics engine  260  may receive location notifications directly from projectile  210  and/or indirectly via a device connected to network  230 , such as the projectile-tracking device  250  or the weapon system  100 . Simulation data, such as but not limited to detailed error-source descriptions (DESDs) and/or error-source weights, of the ballistics engine  260  may be adjusted or otherwise updated using the location notifications, including impact locations, from the projectile  210 . The weapon system  100 , the projectile  210  and/or the projectile-tracking device  250  may also provide information about the projectiles fired by the weapon system  100 , such as charge levels and types of propellant, to the ballistics engine  260 . 
     The combination of functionality of the projectile-tracking device  250  and the ballistics engine  260  may be performed by transmitting data between the projectile-tracking device  250  and the ballistics engine  260  and/or combining software functionality of the projectile-tracking device  250  and the ballistics engine  260 . The simulated results can be transmitted from the ballistics engine  260  to the projectile-tracking device  250 , and actual results may be transmitted from the projectile-tracking device  250  to the ballistics engine  260 . The combination of simulated results determined by the ballistics engine  260  and actual results determined by the projectile-tracking device  250  may lead to improved modeling of the weapon system  100  by ballistics engine  260  and/or improved adjustments of the targeting solution of the weapon system  100  by the projectile-tracking device  250 . In an embodiment of the invention, the functionality of both the projectile-tracking device  250  and the ballistics engine  260  is combined. 
       FIG. 3  shows an example of a projectile  300 , in accordance with embodiments of the invention.  FIG. 3  shows the projectile  300  with a location device  310 , a payload  320 , and a sensor  330 . 
     The location device  310  may transmit one or more location notifications. Location notifications are described in more detail with reference to  FIG. 7  below. The location device  310  may provide one or more location notifications before, during, or after a flight of the projectile  300 . In-flight location notifications about the projectile  300  may be used to determine an impact location of the projectile  300 . 
     A location notification provided after the flight of the projectile  300  also may provide the impact location of the projectile  300 . A highly accurate determination of impact location of a projectile may be made by a location device designed to survive projectile impact and thus provide a location notification with the actual impact location of the projectile. However, a location device not designed to survive projectile impact may be cheaper, more available, and/or more reliable than a location device designed to survive projectile impact. 
     Providing location notifications of the projectile  300  near, but not at, the impact location allows use of location devices not designed to survive projectile impact while still providing information needed to make an accurate estimate of the impact location of the projectile  300 . In an embodiment of the invention, the projectile  300  provides only one or a few in-flight notification when the projectile is near the impact location. Providing one or a few notifications may minimize both power requirements for the location device and minimize the amount of communications required as well. 
     The location device  310  may estimate an impact location of the projectile  300  before reaching the impact location. After estimating the impact location of the projectile, the location device  310  may provide a location notification with the estimated impact location. For example, some weapon systems (e.g., anti-tank weapons) have projectiles carrying two or more sub-payloads: the first sub-payload may be a “precursor charge” used to detonate reactive armor or otherwise prepare a target for the impact of an explosion. The second sub-payload may be a “main charge” located in a position to explode slightly later than the precursor charge to provide more severe damage to the target after the precursor charge has exploded. The location device  310  on a projectile carrying multiple sub-payloads may send a location notification when the first sub-payload impacts the target as an estimate of the impact location of the main charge. The location device  310  may also be able to determine an estimated distance to the target, such as by emitting a pulse of energy (e.g., a radar beam) and measuring the time before receiving an echo of the emitted pulse of energy. 
     The location device  310  may determine the location of the projectile  300  using one or more techniques involving one or more technologies. The location device  310  may determine the location of the projectile  300  using Global Positioning System (GPS) technology. The location device  310  may measure the velocity and/or the acceleration of the projectile  300  and determine the location of the projectile using dead reckoning techniques based on the initial location, velocity, and/or acceleration of the projectile  300 . The location device  310  may determine the location of the projectile  300  by comparing the current location of the projectile to estimated or actual distances to known landmarks. The location device  310  may determine the location of the projectile  300  by detecting location signals, such as GPS transmissions, lasers, and/or radio-frequency waves. Other signals are possible as well. Then, the location device  310  may report a location notification with location information about the detected location signal. 
     The location device  310  may provide location information via a “video feed”, or series of images, from the projectile. The video feed, such as a view from the projectile  300  while in flight, may be used to determine the location of the projectile. The video feed from the projectile  300  may be compared to other video information to determine location information of the projectile  300 ; e.g., comparing landmarks in the video feed from the projectile  300  to landmarks from video from other projectiles or other video information of the area. The video feed comparison may be performed by the location device  310  and/or on a device not on the projectile, such as projectile-tracking device  250 . The video feed may also be used to provide information about the target as well, such as the structural integrity of the target, and other targets, personnel, and/or structures near the target. 
     The location device  310  may provide information via transmitted electromagnetic energy. In particular, the location device may provide information via a laser, directed radio-frequency (RF), or other electromagnetic radiation transmitter. One example of providing information via transmitted electromagnetic energy is providing information via a wired or wireless interface. A wired interface may comprise one or more wires, fibers, or the like that connect the location device to a weapon system and/or a network and permit data transmission between the location device and the network. A wireless interface may comprise a wireless network interface to connect the location device to a network and permit data transmission between the location device and the network. The wireless interface may use one or more wireless communication protocols, such as, but not limited to, WiMAX, Wi-Fi, CDMA, GSM, and/or 3 GSM. 
     As such, the location device  310  may be operable to receive information from the network  230  and/or the weapon system  100 , such as shown in  FIG. 2 . Such received information may comprise requests to transmit or retransmit data, such as a request for a location notification or retransmission of a garbled location notification. The location device  310  may be operable to receive information to adjust a target of the projectile. For example, a projectile may have an engine or other device operable to provide in-course adjustments to a trajectory of the projectile based on the received information to adjust the target of the projectile. 
     Location devices and/or location sub-devices may operate on multiple frequencies, timing, and/or codes. The location device  310  may operate on multiple frequencies simultaneously for redundancy and to make blocking signals from the location device  310  more difficult. The location device  310  may operate using different timing patterns (i.e., one or more fixed timeslots allocated per projectile or a predetermined offset from a reference timing cycle) to reduce the number of overlapping transmissions to and/or from a plurality of projectiles. The location device  310  may operate using multiple codes, such as the identifier of the projectile  300 , to identify transmissions to and/or from a given projectile. 
     As shown in  FIG. 3 , a location device  310  may one or more location sub-devices  312 ,  314 , and  316  as part of the location device  310 . Multiple sub-devices of the location device  310  allow location determination using multiple technologies and/or techniques and provide redundancy in case of failure. For example, projectile  300  may have three location sub-devices that use different technologies, such as Global Positioning System (GPS) location sub-device  312 , a radio-frequency (RF) transmitter sub-device  314  to permit triangulation of RF signals transmitted by RF transmitter sub-device  314 , and a laser reflector location sub-device  316 . Many other location sub-devices are possible as well. 
     The location device  310  may be a passive location device. A passive location device may provide location information about the projectile  300  indirectly, such as in combination with a range-finding device. An example of a passive location device is a mirror or other reflector. For example, the location device  310  may reflect electromagnetic radiation (e.g., laser light) and, thus, the location of the projectile  300  may be determined by use of a laser-range finder or other device capable of radiating electromagnetic radiation acting as a range-finding device. An example laser-range finder may send a laser pulse toward the location device  310 . Then, the laser-range finder may determine the distance to the projectile  310  by (1) measuring the time taken for the pulse to be reflected from the location device  310  and returned to the laser-range finder and (2) determining the distance to the projectile  310  based on the measured time. Other methods of determining the distance to the projectile are possible as well, including but not limited to the use of seismic triangulation. 
     If other types of electromagnetic radiation are reflected from a passive location device  310 , a human eye, radar detector, or other electromagnetic radiation detector may act as a range-finding device. The range-finding device may send one or more location notifications of the projectile, including a location notification of an impact location of the projectile, based on the determined distance to the projectile. 
     Further, a range-finding device may provide observations beyond the location of the projectile in the location notification. As part of determining a position of a projectile, the range-finding device may make other observations such as temperature and/or humidity gradients and make those other observations available via the location notification. For example, humidity gradients may be determined based on radar observations of the atmosphere, such as observations made while observing a flight of a projectile. A range-finding device may make many other observations beyond these examples as well. 
     The location device  310  may comprise a radio-frequency identification (RFID) device. An RFID device may passively await a request signal and respond with a response signal. The response signal may comprise a location notification. The RFID device may have a battery, preferably a long-lived battery, to power the active RFID device and provide a stronger response signal. Alternatively, the RFID device may not have a battery, and thus depend on the power of the response signal to generate the response signal. 
     After the projectile  300  has been fired by a weapon system, such as weapon system  100 , the payload  320  of the projectile  300  may explode. The payload  320  may explode after an amount of time has passed after projectile  300  is fired, upon projectile  300  reaching a certain altitude, or for other reasons. 
     The payload  320  may comprise an explosive charge made of high explosive, a nuclear warhead, and/or other materials that act as an explosive. The lethal radius of projectile  300  may depend on the force of the explosion caused by the explosive charge of the payload  320  and/or any materials caused to fly because of the explosion of the projectile  300 . Such flying materials may be fragments of the projectile  300 , shrapnel or other foreign bodies carried by projectile  300 , portions of a target, and/or other materials caused to fly because of the explosion of the projectile  300 . The payload  320  may partially or wholly comprise non-explosive material, such as iron or depleted uranium. Other non-explosive materials may be used as part or the entire payload  320 . The payload  320  may be divided into two or more sub-payloads, such as the precursor charge and main charges described above. The non-explosive material may be used to provide additional kinetic energy when the projectile reaches an impact location (e.g., anti-tank projectiles, rail gun projectiles, and cannonballs). 
       FIG. 3  shows that the projectile  300  equipped with a sensor  330 . The projectile  300  may also be equipped with one or more sensors to provide sensor-based information, such as projectile velocity, projectile acceleration, temperature, humidity, wind speed/direction, and/or other sensor-based data. The sensor-based information may be used to aim the weapon system  100 , among other uses. 
     An Example Scenario and Projectile-Status Display 
       FIG. 4  shows an example scenario with projectile-tracking device  250  tracking a plurality of the projectiles  430 ,  432 ,  434 ,  436 ,  438 ,  440 , and  442  fired by a plurality of the weapon systems  410 ,  412 ,  414  at a plurality of targets  420  and  422 , in accordance with an embodiment of the invention. The projectile-tracking device  250  may be connected to a plurality of weapon systems.  FIG. 4  shows the projectile-tracking device  250  connected to the weapon systems  410 - 414 . 
       FIG. 4  shows the projectiles  430 - 442  fired by the weapon systems  410 - 414  at a plurality of targets  420 - 422 .  FIG. 4  shows the projectiles  430 - 440  communicatively connected to the projectile-tracking device  250  and projectile  442  is shown not communicatively connected to the projectile-tracking device  250 . Each communicatively-connected projectile may provide one or more location notifications to the projectile-tracking device  250 . 
     A projectile may not be communicatively connected to the projectile-tracking device, such as a projectile equipped with only passive location devices/sub-devices. A range-finding device may provide location notifications about projectiles that are not communicatively connected to the projectile-tracking device  250 , as described above with reference to  FIG. 3 . 
       FIG. 5  shows an example projectile-status display  500  of the projectile-tracking device  250 , in accordance with embodiments of the invention. The projectile-status display  500  may provide information about a scenario, such as the scenario shown in  FIG. 4 .  FIG. 5  shows the projectile-status display  500  indicating weapon systems  510 ,  512 , and  514 , with the weapon system  510  identified with identifier “Weapon System (WS)  1 ”, the weapon system  512  with identifier “WS 2 ”, and the weapon system  514  with identifier “WS 3 ”.  FIG. 5  shows the weapon system  512  with a type of weapon of “Abrams Tank” and a weapon system status of “90%”.  FIG. 5  shows a weapon-system status for the weapon system  510  having a category of “intact” and a weapon-system status for the weapon system  512  having a numerical value of “95%”. A weapon-system status may be indicated in a distinctive font, shape, color, type face, and/or using other distinguishing characteristics. 
       FIG. 5  shows the projectile-status display  500  indicating a velocity  516  for the weapon system  514 , using an arrow for a direction of the velocity  516  with an arrow and a speed or magnitude of the velocity  516  of “10 km/hr”. 
       FIG. 5  shows the projectile-status display  500  indicating targets  520 ,  522 , and  524 , with target  520  identified by identifier “Target  1 ”, target  522  identified by identifier “Target  2 ”, and target  524  identified by identifier “Target  3 ”.  FIG. 5  shows target  520  with a type of weapon of “120 mm mortar” and a weapon system status of “90%”.  FIG. 5  shows target status for target  522  having a category of “intact” and target status for weapon system  524  having a numerical and categorical value of “90% destroyed”. A target status may be indicated in a distinctive font, shape, color, type face, and/or using other distinguishing characteristics. 
       FIG. 5  shows the projectile-status display  500  indicating a creek  530 . Other geographical features, such as, but not limited to hills, mountains, valleys, other bodies of water (e.g., oceans, seas, rivers, and lakes), and/or deserts, may be indicated in projectile-status display  500 . A geographical feature may have an identifier.  FIG. 5  shows the creek  530  with an identifier “Battle Creek”. Other display techniques may be used by the projectile-status display  500  as well, such as but not limited to, topographical displays, Mercator projections, displays of latitude and/or longitude lines, displays on a grid, and/or coordinate system. 
       FIG. 5  shows the projectile-status display  500  indicating a village  540 . Other locations of human settlement, such as, but not limited to, houses, huts, igloos, caves, hamlets, towns, and cities, may be indicated on the projectile-status display  500 . A location of human settlement may have an identifier.  FIG. 5  shows the village  540  with an identifier of “Pennfield Village.” A projectile-status display may indicate locations of human settlement using a distinctive font, color, shape, type face, and/or using other distinguishing characteristics. 
       FIG. 5  shows the projectile-status display  500  indicating the impact locations  550 ,  552 ,  554 ,  556 , and  558 . Each impact location may be indicated using a distinctive font, color, shape, type face, and/or using other distinguishing characteristics.  FIG. 5  shows the impact locations  550 - 558  using large black X&#39;s. Many other possible indications of impact locations of shots fired by the weapon systems are possible as well. The indication of an impact location may indicate a source of an impact location (i.e., which weapon system fired a projectile that landed at the indicated impact location), such as the “WS 1 ” indication of the impact location  550 . 
       FIG. 5  shows the projectile-status display  500  indicating in-flight projectiles  560  and  562 .  FIG. 5  shows a direction of fire  570  from the weapon system  512  to the projectile  560  and a direction of fire  572  from the weapon system  514  to projectile  562 , where both direction of fire  570  and direction of fire  572  are indicated as lines from a weapon system to a projectile in  FIG. 5 . Other ways, such as arrows or “comet trails”, of indicating directions of fire are possible as well. A direction of fire shown on the projectile-status display  500  may indicate the direction as targeted (e.g., in the direction of the azimuth used to fire a projectile) and/or as determined based on location notification(s) received from a projectile. 
     The projectile-status display  500  may integrate information from multiple information sources and provide the integrated information to a user of the projectile-status display, such as an information source that tracks impact locations indicate one or more impact locations of shots fired by one or more targets.  FIG. 5  shows the projectile-status display  500  indicating an impact location  580  of a shot fired by a target and that “Target  1 ” is the source of the impact location  580 . Each impact location may be indicated using a distinctive font, color, shape, type face, and/or using other distinguishing characteristics. 
       FIG. 5  shows the projectile-status display  500  with a meteorological information display  590 , indicating a temperature of “20° C.”, wind speed and direction information of “10 km/h NNW”, precipitation of “None”, and humidity information of “45%”. Meteorological information used in the meteorological information display  590  may be determined from one or more sensors on one or more projectiles and/or may be determined from other information sources, such as the information sources  140 . 
     User input may be used to configure the projectile-status display  500 . User input may be used to configure the projectile-status display  500  by selecting, removing, and/or modifying graphical characteristics of the indications shown in the projectile-status display  500 , including but not limited to the herein-described indications of the projectiles, impact locations, targets, weapon systems, geographical features, meteorological information, and/or locations of human settlement. 
     An Example Computing Device 
       FIG. 6  is a block diagram of an example computing device  600 , in accordance with embodiments of the invention.  FIG. 6  shows an example computing device  600  comprising a processing unit  610 , data storage  620 , a user interface  630 , and a network-communication interface  640 , in accordance with embodiments of the invention. A computing device  600  may be a desktop computer, laptop or notebook computer, personal data assistant (PDA), mobile phone, or any similar device that is equipped with a processing unit capable of executing computer instructions that implement at least part of the herein-described functionality of information sources  240 , projectile-tracking device  250 , and/or ballistics engine  260 . Thus, the computing device  600  may perform functions described herein as being performed by a projectile-tracking device, a ballistics engine, and/or information sources. 
     The processing unit  610  may include one or more central processing units, computer processors, mobile processors, digital signal processors (DSPs), microprocessors, computer chips, and similar processing units now known and later developed and may execute machine-language instructions and process data. 
     The data storage  620  may comprise one or more storage devices. The data storage  620  may include read-only memory (ROM), random access memory (RAM), removable-disk-drive memory, hard-disk memory, magnetic-tape memory, flash memory, and similar storage devices now known and later developed. The data storage  620  comprises at least enough storage capacity to contain data structures  622 , and machine-language instructions  624 . The data structures  622  comprise at least the herein-described location notifications. The machine-language instructions  624  contained in the data storage  620  include instructions executable by the processing unit  610  to perform some or all of the functions of the herein-described functionality of information sources  240 , projectile-tracking device  250 , and/or ballistics engine  260 , including but not limited to the functions of method  800  described with reference to  FIG. 8  below. 
     The user interface  630  may comprise an input unit  632  and/or an output unit  634 . The input unit  632  may receive user input from a user of the computing device  600 . The input unit  632  may comprise a keyboard, a keypad, a touch screen, a computer mouse, a track ball, a joystick, and/or other similar devices, now known or later developed, capable of receiving user input from a user of the computing device  600 . The output unit  634  may provide output to a user of the computing device  600 . The output unit  634  may comprise one or more cathode ray tubes (CRT), liquid crystal displays (LCD), light emitting diodes (LEDs), displays using digital light processing (DLP) technology, printers, light bulbs, and/or other similar devices, now known or later developed, capable of displaying graphical, textual, and/or numerical information to a user of the computing device  600 . 
     The network-communication interface  640  is configured to send and receive data and may include a wired-communication interface and/or a wireless-communication interface. The wired-communication interface, if present, may comprise a wire, cable, fiber-optic link or similar physical connection to a wide area network (WAN), a local area network (LAN), one or more public data networks, such as the Internet, one or more private data networks, or any combination of such networks. The wireless-communication interface, if present, may utilize an air interface, such as an IEEE 802.11 (e.g., Wi-Fi) interface to a WAN, a LAN, one or more public data networks (e.g., the Internet), one or more private data networks, or any combination of public and private data networks. 
     An Example Location Notification 
       FIG. 7  is a schematic view of an example location notification  700 , in accordance with embodiments of the invention. A location notification provides information about a projectile that has been fired by a weapon system.  FIG. 7  shows the location notification  700  with location information  710 , timing information  720 , velocity information  730 , projectile information  740 , weapon-system information  750 , target information  760 , and sensor-based information  770 . It is to be understood that a specific location notification  700  may not comprise all of the information, or may comprise more information, than described herein. 
     The location notification  700  may comprise location information about the projectile fired by the weapon system, such as location information  710 .  FIG. 7  shows location information  710  with coordinate information  712 . The coordinate information  712  may comprise the coordinates of a projectile expressed using a two or three dimensional coordinate system, such as [x,y] or [x,y,z] coordinates for a Cartesian coordinate system. The coordinate information  712  may use latitude, longitude, and, perhaps elevation above mean sea level to express location or may be expressed using polar coordinates, spherical coordinates, or another coordinate system. The location information  710  may comprise information about a location signal as location signal  714 . The location signal  714  may provide an identifier of an observed location signal and/or an indication of strength of the observed location signal. 
       FIG. 7  indicates that the location notification  700  may comprise timing information, such as timing information  720 . The timing information  720  may include one or more times, such as the time that (a) the projectile was fired, (b) the location of the projectile was determined, or (c) the location notification was transmitted. 
     The location notification  700  may comprise data about a velocity of the projectile fired by the weapon system, such as velocity information  730 . The velocity of the projectile may comprise a magnitude of the velocity and/or a direction of the velocity.  FIG. 7  shows velocity information  730  with magnitude  732  and direction  734 . 
     The magnitude  732  may be expressed in terms of units of measurement. Example units of measurement for velocity are kilometers/hour, miles/hour, meters/second or feet/second. The velocity may be indicated with respect to one or more fixed directions, such as indicating the velocity as an angle relative to true north. The velocity may be expressed as one or more vector components, such as a component in a north-south direction, a component in an east-west direction, and/or a component in an up-down direction. The sign of magnitude  732  may indicate a direction of the projectile; for example, a positive magnitude may indicate the projectile is traveling in the direction of the target and a negative magnitude may indicate the projectile is traveling away from the target. Many other methods of expressing the velocity are possible as well. 
     The direction  734  may be expressed as a vector in a coordinate system, including but not limited to, any coordinate system used to express the coordinate information  712 . In particular, the direction  734  may be expressed using the same coordinate system as the coordinate information  712 . 
     A location notification may comprise data about the projectile fired by the weapon system, such as projectile information  740 .  FIG. 7  shows projectile information  740  with an identifier  742 , a propellant/charge level  744 , and payload information  746 . The identifier  742  may provide identification information about the projectile, such as a serial number or tracking number of the projectile. The propellant/charge level  744  may include information about the propellant and/or charge level for firing the projectile. The payload information  746  may include information about the payload of the projectile, such as a type of payload and/or amount of payload. 
     A location notification may comprise data about the weapon system, such as weapon-system information  750 .  FIG. 7  shows weapon-system information  750  with an identifier  752  and a location  754 . The identifier  752  may provide identification information about a weapon system that fired a projectile, such as a serial number, tracking number, or other identifier of the weapon system. The location  754  may provide information about the location of the weapon system, such as the location of the weapon system when the projectile was fired. 
     The location notification  700  may comprise information about a target of the projectile fired by the weapon system, such as target information  760 .  FIG. 7  shows the target information  760  with an identifier  762  and a location  764 . The identifier  762  may include an identifier of a target, such as shown in projectile-status display  500 . The location  764  may include a location of the target, expressed in a coordinate system, such as the coordinate systems described above for the coordinate information  712  and the direction  734 . 
     A location notification may comprise sensor-based data, such as sensor-based information  770 .  FIG. 7  shows the location notification  700  with sensor-based information  770 . For example, the projectile  300  may also be equipped with one or more sensors  330  to provide sensor-based information, such as projectile velocity, projectile acceleration, temperature, humidity, wind speed/direction, and other sensor-based data. The data gathered from the one or more sensors  330  may be reported as sensor-based information  770 . Sensor-based information  770  may comprise a type of data gathered and/or a measurement for each datum gathered by the one or more sensors  330 . 
     An Example Method for Adjusting the Targeting of a Weapon System 
       FIG. 8  is a flowchart of an example method  800 , in accordance with embodiments of the invention. It should be understood that each block in this flowchart and within other flowcharts presented herein may represent a module, segment, or portion of computer program code, which includes one or more executable instructions for implementing specific logical functions or steps in the process. Alternate implementations are included within the scope of the example embodiments in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the described embodiments. 
     The method  800  is a method for adjusting a targeting solution of a weapon system that fires one or more projectiles at one or more targets. The method  800  may be performed by a projectile-tracking device. The functions of a projectile-tracking device may be performed by computer software executed on a computing device, such as computing device  600 , configured to execute some or all of the steps of herein-described the method  800 . 
     At block  810 , the projectile-tracking device may receive a location notification about a projectile. The location notification may be received about an in-flight projectile. The location notification may be sent from the location device of the projectile. The location notification may be sent by a device, such as a range-finding device, monitoring the projectile equipped with a passive location device. The location notification may comprise the some or all of the information in location notification  700 , shown in  FIG. 7 . 
     At block  820 , the projectile-tracking device may determine an impact location of the projectile based on a location notification. The location notification may comprise the impact location of the projectile. Alternatively, the location notification may provide location information of an in-flight projectile, such as location information when the projectile was near to the impact location. The in-flight location information may be used to estimate the impact location of the projectile. An estimate of the impact location of the projectile may be determined mathematically, such as by use of the ballistic equation and/or curve-fitting algorithms. 
     At block  830 , the projectile-tracking device may adjust the targeting solution of a weapon system, based on the determined impact location of the projectile. The targeting solution may comprise an azimuth, an elevation, and/or a location of the weapon system. 
     The projectile-tracking device may adjust the targeting solution of the weapon system directly, such as by requesting the weapon system to change the azimuth of the weapon system, elevation of the weapon system, location of the weapon system, or any combination thereof. The projectile-tracking device may adjust the targeting solution of the weapon system within one or more ranges of parameter values, such as adjusting the targeting solution within a limited range of elevation values. The projectile-tracking device may directly adjust some, but not all parameters of the targeting solution, such as only adjusting azimuth and elevation, but not the location of the weapon system. 
     The projectile-tracking device may indirectly adjust the targeting solution of the weapon system. The projectile-tracking device may indirectly adjust the targeting solution by displaying impact locations and/or suggested targeting solutions to the weapon system. 
     User input may be provided to the projectile-tracking device to: (a) select direct and/or indirect adjustments to the targeting solution, (b) confirm an adjustment to the targeting solution, (c) partially override an adjustment to the targeting solution, (d) completely override an adjustment to the targeting solution, (e) configure the projectile-tracking device, including the projectile-status display  500  shown in  FIG. 5 , and/or (f) specify one or more ranges of parameter values for the targeting solution. 
     The projectile-tracking device may adjust an error-weighting function of the weapon system. The projectile-tracking device may adjust the error-weighing function by providing location notifications and/or impact locations to a ballistic engine. In an embodiment of the invention, the projectile-tracking device may comprise the functionality of the ballistic engine and use the determined impact locations to adjust the error-weighting function. The error-weighting function is a function that estimates the amount of error of a weapon system based on one or more error-source weights. The error-source weights comprise estimates of an effect of each error source on the error of a weapon system. 
     The error-weighting function can be used to predict actual performance of a weapon system. The error-weighting function may, in combination with the ballistics equation of motion, predict an actual trajectory of a shot fired using the weapon system by providing an accurate model of the perturbation from the ideal trajectory induced by errors in the weapon system. 
     At block  840 , the projectile-tracking device may determine a status of a target. The status of the target may be determined based on the determined impact location and information about the payload of the target. A lethal radius may be determined by the projectile-tracking device based on the payload of the projectile. Then, the status of the target may be determined based on comparing the lethal radius to the distance between the impact location and the target. For example, if the distance between the impact location and the target is less than the lethal radius, the status of the target may be “destroyed.” As another example, if the distance between the impact location and the target is slightly larger than the lethal radius, the status of the target may be “partially destroyed”. The projectile-tracking device may use other information sources to provide the status of the target, perhaps based on the location of the target and the impact location. 
     At block  850 , the projectile-tracking device may display a projectile-status display. The projectile-status display may comprise some or all of the information of the projectile-status display. 
     At block  860 , a determination may be made if more projectiles are to be fired. For example, the determination may be made that no more projectiles are to be fired if (a) no more targets are available to the weapon system, (b) no more projectiles are available for the weapon system to fire, and/or (c) user input to the projectile-tracking device. If more projectiles are to be fired, the method  800  proceeds to block  810 . If no more projectiles are to be fired, the method  800  ends. 
     Exemplary embodiments of the present invention have been described above. Those skilled in the art will understand, however, that changes and modifications may be made to the embodiments described without departing from the true scope and spirit of the present invention, which is defined by the claims. It should be understood, however, that this and other arrangements described in detail herein are provided for purposes of example only and that the invention encompasses all modifications and enhancements within the scope and spirit of the following claims. As such, those skilled in the art will appreciate that other arrangements and other elements (e.g. machines, interfaces, functions, orders, and groupings of functions, etc.) can be used instead, and some elements may be omitted altogether. 
     Further, many of the elements described herein are functional entities that may be implemented as discrete or distributed components or in conjunction with other components, in any suitable combination and location, and as any suitable combination of hardware, firmware, and/or software.