BACKGROUND OF THE INVENTION
The present invention claims priority under 35 U.S.C. § 120 from the co-pending U.S. application entitled “PASSIVE WIND READING SCOPE,” filed on Mar. 13, 2001, and assigned Ser. No. 09/805,608, and which is incorporated in its entirety herein by reference.
The present invention generally is related to shooting, and particularly is related to providing aiming assistance for precision shooting at extended distances.
Recreational shooting at customary target distances as compared to precision shooting at extended ranges, e.g., ranges approaching or exceeding one-thousand yards, is like comparing a casual round of weekend golf to match play at a professional golf tournament. In other words, there essentially is no comparison between the skill set required for recreational shooting and the skill set required for successful, long-range shooting. Indeed, the knowledge, skill, and equipment required for the reliable engagement of targets at extended ranges are possessed by few shooters. Such shooters primarily are members of select military units or special-purpose law enforcement agencies, although a limited number of them may be private individuals engaged in specialized recreational shooting.
Regardless, the cumulative effects of environmental and systemic influences on bullet trajectory become so multiplied over extended shooting distances that reliable target engagement requires the shooter to understand and compensate for such influences. Oftentimes, such compensation manifests itself as an “aiming point adjustment,” wherein the shooter's aiming point is adjusted left or right, and/or up or down from the nominal aiming point of the weapon as compensation for the expected bullet trajectory in consideration of the aforementioned influences.
For example, the nominal aiming point of a rifle-mounted aiming scope generally is the intersection of its reticle lines, which lines often are referred to as the “crosshairs.” These crosshairs represent the nominal impact point of the bullet, assuming the scope has been “zeroed in” for the rifle to which it is attached. However, as might be guessed, the bullet's actual point of impact varies as a function of many variables, with wind and ambient pressure/temperature prominent among those variables.
Wind in particular represents a difficult-to-account for variable that can dramatically alter a bullet's point of impact. Indeed, the need to properly account for wind increases significantly as the target ranges increases. In compensating for wind, an expert shooter might use his or her knowledge and past experience to “estimate” the expected wind-induced leftward or rightward deflection of a bullet to be fired and make the corresponding aiming point compensation by shifting the scope's crosshairs either left or right of the desired impact point. Such an adjustment commonly is referred to as “windage hold-off.”
At extreme shooting distances or with significant crosswind, such hold-off may amount to several feet of sideways aiming point compensation. Of course, the “trick” comes in accurately reading the downrange wind speed, and then in understanding how that value of wind speed will affect the bullet's flight.
Existing compensation methods typically generate windage-based aiming point compensation values based on simplified relation between target range and estimated wind speed. More particularly, the conventional art does not consider the changes in wind effects resulting in changing ambient temperature and atmospheric pressure. In other words, the conventional approach to windage hold-off estimation would predict the same wind effect for the same target range and wind speed regardless of even dramatic differences in temperature and/or pressure.
- SUMMARY OF THE INVENTION
One could obtain potentially dramatic gains in long-range accuracy by incorporating such environmental parameters into windage calculations. However, one potential downside of such gains in accuracy is that a larger number of shooters become capable of highly accurate, long-range shooting. In other words, improving windage compensation would make a larger population of shooters capable of deadly accurate long-range shooting. To avoid such indiscriminate empowerment of shooters, some of whom might use the very same accuracy improvements against the intended beneficiaries of the improved windage compensation, an ideal aiming system would be structured such that its operation, or at least its improved accuracy, would be denied to unauthorized users.
The present invention comprises an apparatus and methods to provide precision aiming assistance to a shooter. More particularly, an exemplary aiming system configured according to the present invention provides selective aiming assistance to the shooter based on obtaining a valid windage variable that is compensated for at least one of ambient temperature and ambient pressure. Because computation of a “hold-off” value by the aiming system is based on the availability of a valid windage variable, the precision aiming assistance it provides is available only to users in possession of the required windage compensation table, or in possession of one or more authorization values that enable access to the required windage compensation table by the aiming system.
For example, in an exemplary embodiment, the aiming system remains in a “standby” mode if a valid windage variable is not available, wherein no aiming assistance is provided to a user of the aiming system. If a valid windage variable is available (assuming any other parameters required for computation of the hold-off value also are available), the aiming system transitions to an “active” mode, wherein the system provides aiming assistance to the user. Thus, in active mode, the aiming system obtains or otherwise receives a valid windage variable from a windage table that is based on ballistic coefficients that are compensated for at least one of an ambient temperature and an ambient pressure, and computes the hold-off value based on a defined set of parameters that includes at least the valid windage variable. Note that the aiming system 10 might, in some embodiments, transition to active mode, i.e., compute a hold-off value based on the user entering an invalid windage variable; however, such computation would result in the user being provided an incorrect hold-off value, and thus the “precision” aiming assistance of the aiming system 10 effectively is denied to shooters not in possession of a printed windage table 16, or not authorized to access an electronically stored version of that table.
In any case, if the aiming system receives the windage variable, such as by receiving data input from a user having access to a printed or electronically stored copy of the windage compensation table, an exemplary defined set of parameters needed to compute the hold-off value includes a wind speed, a target range, and a valid windage variable. Where the aiming system includes a locally stored copy of the windage compensation table, the exemplary set of parameters may include one or more additional values such as ambient pressure and/or temperature, muzzle velocity, bullet weight, as needed for indexing into the windage compensation table to obtain the correct windage variable.
Thus, in an exemplary embodiment, the aiming system comprises: a wind-reading scope to determine a wind speed; a windage compensation table to provide a windage variable, wherein the windage table is based on ballistic coefficients compensated for at least one of an ambient temperature and an ambient pressure; and a processing module to compute the hold-off value based on at least the wind speed and the windage variable.
In turn, an exemplary processing module comprises: an interface circuit to receive the windage variable; and a processor circuit programmed to compute the hold-off value for use with the wind-reading scope based on, in an exemplary embodiment, the target range, the wind speed, and the windage variable. As noted, the processor circuit may use one or more additional parameters if it is required to obtain the windage variable based on indexing into an electronically stored copy of the windage compensation table.
With regard to such parameters, in at least one embodiment, the aiming system includes one or more parameter sensors for determining one or more of the defined set of parameters used in computing the hold-off value, such as temperature and/or pressure sensors, target ranging sensors, etc. However, in other embodiments, such information is entered into the aiming system by a user, such as by inputting numeric data into a keypad included in the aiming system.
Additional exemplary variations arise with regard to implementation of the interface circuit enabling receipt of the windage variable by the processor circuit, the details of which vary as needed. For example, in one exemplary embodiment, the interface circuit includes a user interface, such as a keypad and optional display. With that arrangement, the user enters the windage variable via the keypad based on obtaining it from a printed windage compensation table. Alternatively, the aiming system might store the windage compensation table as an electronic look-up table maintained in a memory circuit that it accesses responsive to receiving an authorization value input by the user via the keypad.
In still other embodiments, the aiming system further includes a security module that is communicatively coupled to the processing module. Such coupling is, in an exemplary embodiment, based on wireless signaling between the security module and processing module. Thus, in this embodiment, an exemplary interface circuit comprises a receiver circuit to receive wireless signals from the security module and to transfer data contained therein to the processor circuit. Thus, the security module transmits an authorization value to the processing module that enables computation of the hold-off value, i.e., the security module enables the processing module to transition to active mode operation.
As such, an exemplary security module sends an authorization value to the processing module that enables the processing module to enter active mode. In one embodiment the authorization value comprises a valid windage variable and, as such, an exemplary security module comprises memory and logic circuits to store the windage compensation table and obtain the windage variable therefrom, and a transmitter circuit to transmit the windage variable to the processing module.
Alternatively, the windage compensation table is stored in the processing module and the security module transmits an authorization code as the authorization value, which code enables the processing module to access the locally stored windage compensation table. In still other embodiments, the security module functions essentially as a passive transponder that provides a short-range enabling signal to the processing module, such that the processing module will not function, or at least will not transition to active mode operation unless the security module is nearby. Note, too, that in all such embodiments, the security module itself may include a user interface for inputting authorization information and/or other parameters related to the computation of the hold-off value.
BRIEF DESCRIPTION OF THE DRAWINGS
Of course, additional features and advantages of the present invention will be apparent to those skilled in the art upon reading the following detailed description and viewing the accompanying figures. However, such information represents exemplary embodiments of the invention and it should be understood that the present invention generally provides a precision aiming system that provides its aiming point assistance to users on a selective basis. That is, the precision aiming assistance provided by the present invention is available only where access to a valid windage variable has been enabled, directly or indirectly, by the user. Therefore, where the user does not possess the required windage compensation table from which valid windage variables are obtained, or does not possess access authorization to such information, the aiming system of the present invention does not provide aiming assistance to the user, or at least does not provide its highest level of precision aiming assistance to the user.
FIG. 1 is a diagram of an exemplary aiming system according to the present invention.
FIG. 2 is a diagram of an exemplary field-of-view display for a wind-reading scope of an exemplary aiming system.
FIG. 3 is a cutaway diagram of an exemplary display arrangement for the wind-reading scope.
FIG. 4 is a diagram of an exemplary functional arrangement for a processing module of an exemplary aiming system.
FIG. 5 is a diagram of exemplary details of the processing module.
FIG. 6 is a diagram of additional exemplary details of the processing module.
FIG. 7 is a diagram of exemplary details for the aiming system, including a security module.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 8 is a diagram of exemplary operating logic for the aiming system.
FIG. 1 illustrates a rifle 8 and an exemplary aiming system 10 that may be used to provide aiming assistance to a shooter. The exemplary aiming system 10 comprises a processing module 12, a wind-reading scope 14, and a windage compensation table 16. It should be understood that while the wind-reading scope 14 as shown serves as the aiming/targeting scope of the rifle 8, the present invention contemplates other arrangements, such as where the wind-reading scope 14 is a “spotting scope,” for example, such as might be used by the non-shooting person in a two-person sniper team.
In the exemplary embodiment illustrated, the processing module 12 includes a user interface comprising a display 18 and keypad 20, and optionally includes control inputs 22A and 22B, which, in some embodiments, may be used to aid or control determination of wind-speed by the wind-reading scope 14. An exemplary embodiment of wind-reading scope 14 optionally includes control inputs 22A and 22B, which may be conveniently positioned on a mounting portion 24 of the scope 14, and further includes an elongated housing 26 containing sighting optics and a display 28 positioned in a viewing end of the scope 14.
FIG. 2 depicts an exemplary arrangement of elements for display 28 as viewed through the scope's field of view. A reticle 30 comprises crossing horizontal and vertical aiming lines, the intersection of which represents a “nominal” aiming point that is, absent any aiming compensation information, positioned at the desired point of bullet impact on the target image as viewed through the scope 14. The reticle 30 may be subdivided along regular intervals to assist with aiming point adjustment based on vertical and horizontal hold-off values. Such subdivisions may be based on minor/major tick marks, which may have a regular spacing determined in mils so that the tick marks may be used for determining target hold-off in mils.
Display 28 further includes additional display elements 32 that may be used to display wind speed and hold-off value information, both in mils and/or MOA format. In an exemplary embodiment, display elements 36 indicate whether hold-information represents Minutes-of-Angle (MOA) or polar mils (MILS), both of which are common units for expressing angular hold-off values for aiming point adjustment. Display elements 38A and 38B may be used to indicate whether the computed hold-off is leftward or rightward oriented, while display element 40 may be used to display a wind speed value. Displaying wind speed value may be particularly useful where the user is expected to enter the wind speed into processing module 12 as a parameter input for hold-off computation.
In exemplary operation, a user of the aiming system 10, which in the depicted embodiment may be the shooter, matches the speed and direction of laterally translating indicia 34, e.g., Liquid Crystal Display (LCD) or Light Emitting Diode (LED) elements, visible on display 28 to actual downrange wind conditions as observed through the field of view. Such observations may be based on the user matching the speed and direction of the translating indicia 34 to the lateral movement of an observed heat mirage along some downrange point relative to the intended target. Such matching operations may be based on the user controlling control inputs 22A and 22B, which set the direction and translation speed.
Thus, where the control inputs 22A and 22B are located at processing module 12, translation control signals pass from module 12 to scope 14 to control indicia translation. If the control inputs 22A and 22B are located at scope 14, then the indicia control signals may be locally generated at scope 14. In either case, wind speed may be determined at module 12 or at scope 14, in which case, in an exemplary embodiment, scope 14 provides a wind speed value to module 12 for use in hold-off computations. Note that in at least one embodiment, indicia 34 may be spaced apart according to the reticle tick mark spacing such that final aiming hold-off assistance is provided to the user by illuminating the individual element within the set of indicia 34 that most closely corresponds to the calculated left or right hold-off adjusted aiming point.
FIG. 3 illustrates exemplary details for display 28, wherein a display controller 50 controls a display circuit 52 (which may include separate or combined LCD and/or LED elements for display elements 32 and indicia 34), and wherein display circuit 52 is supported by a transparent member 54, which may comprise a portion of the scope's optical system. Thus, a user of the scope 14 is presented with a scope image comprising a field of view for viewing an image of the downrange target and one or more overlaid display elements, including indicia 34.
Display controller 50 may be a dedicated control circuit, or may be a general purpose logic circuit programmed to control display circuit 52 and, optionally, to interface with processing module 12 via interface conductors 56, which may be externally connected to processing module 12 using strain relief 58 and cable 60. Of course, such details may be altered as needed or desired. For example, a wireless interface may be used to communicatively couple circuit elements in scope 14 with circuit elements in processing module 12. Also, it should be noted that economic and packaging advantages may be derived from implementing display 28 using chip-on-glass manufacturing techniques, and that those techniques or other advanced manufacturing processes would allow implementation of the processing module 12 as part of scope 14, and that such integration is contemplated within the present invention.
Regardless, aiming system 10 provides precision aiming assistance to a shooter based on its determination of expected wind effect on the round (bullet) to be fired from the rifle 8. Unlike conventional ballistic computers, the aiming system 10 bases its computation of aiming hold-off, i.e., a lateral aiming point adjustment relative to the intended target to compensate for downrange crosswind, on a windage variable that is itself compensated for environmental effects, such ambient temperature and pressure. Use of the windage variable enables the aiming system 10 to determine extremely precise hold-off values, thereby enabling deadly accuracy at extended shooting ranges.
In contrast, conventional ballistic processing bases wind effect computations on fixed windage factors, which may be expressed as,
where x equals the computed lateral displacement, which may be expressed in terms of aiming hold-off, wind speed is in miles-per-hour, range is in yards to the intended target, and A is a wind drift factor for a particular ballistic coefficient value, that is determined using a set distance and set atmospheric conditions and is invariant with respect to actual temperature and pressure conditions. Thus, for the same target range and crosswind speed values, wind drift estimation uses the same constant “A” and thus predicts the same wind drift effect even where the ambient temperature and/or ambient pressure vary significantly between two different shooting scenarios.
More particularly, with conventional shooting techniques, long range competition or target shooters use the advertised ballistic coefficient of a given bullet, enter this information into a ballistic program and record the predicted wind drift for a given distance and given cross-wind speed. This value might be thought of as a “reference drift” value. Such a shooter would, once positioned at the shooting distance, then use a spotting scope to estimate wind speed by eye. The actual shooting distance and estimated wind speed allow the shooter to cross-reference the wind chart to obtain an expected drift for his or her estimated distance and wind speed. However, this expected drift is based on the reference drift value irrespective of changes in atmospheric conditions, i.e., changes in pressure and temperature, which affect air density and thus alter the bullet's drift characteristics.
Because such techniques do not compensate for changes in temperature and barometric pressure, if the actual shooting conditions are not reasonably close to the laboratory conditions existent when the ballistic coefficient for the shooter's bullet was established, the bullet's actual drift characteristics may deviate significantly from the predicted drift characteristics. Thus, using the conventional reference drift value to estimate or otherwise predict the bullet's actual drift under actual shooting conditions can induce significant errors.
As an example of conventional drift compensation, assume that the shooter's bullet, as based on its advertised ballistic coefficient, has a reference drift value of 10 MOA at 1000 meters, then, for an actual target range of 700 meters and an actual crosswind speed of 5 miles per hour, Equation (1) yields (5×7)/10=3.5, which indicates a 3.5 MOA adjustment to compensate for crosswind. The drift compensation factor “A” in this example 10, and was derived by dividing the reference drift of the projectile, for example, a 173 grain boat-tail full metal jacket match bullet, in minutes of angle into the actual range in meters with the last zero of the range dropped. As another example, assume that, for a given bullet, its reference drift value is 8 MOA at 1000 meters. Thus, the calculated drift compensation factor would be 100/8=12.5, which might be rounded down to 12 or up to 13 for ease of use.
However, as before, the drift factor is not compensated in any way for changes in atmospheric pressure or temperature. This failure to compensate for environmental conditions results in a “built in” aiming hold-off error that arises whenever the actual atmospheric conditions differ from those conditions used to obtain the fixed reference drift value. Typically, the reference conditions are approximately 60 degrees Fahrenheit and 29.53″ of barometric pressure.
A further shortcoming of the above hold-off value computation is that the predicted wind drift is generated in minutes of angle but most aiming scopes are based on mils, which requires a conversion factor of 3.44. Thus, the shooter is required to take the extra step of converting the MOA-based hold-off value to a mils-based hold-off value that can be used with the aiming reticle of the scope.
According to the present invention, the windage compensation table 16 is implemented as a plurality of windage variable values that are derived from ballistic coefficients compensated for temperature and/or pressure effects. That is, rather than the same ballistic coefficient being used irrespective of actual temperature and pressure, the present invention contemplates the use of ballistic coefficients that reflect pressure and/or temperature changes. Thus, in an exemplary embodiment, obtaining the correct windage variable in a particular shooting scenario comprises indexing into table 16 based on temperature and/or pressure and muzzle velocity to obtain the appropriate compensated ballistic coefficient, and then indexing into the tabulated windage variables based on the actual target range and the previously obtained compensated ballistic coefficient.
The windage compensation table 16 may be implemented as a set of printed “cards,” which may be laminated for durability. In an exemplary embodiment, the tabulated data embodied in the windage compensation table consists of matrix data (e.g., row/column data) that allows the user to locate a compensated ballistic coefficient using the current outside temperature and barometric pressure. By reading down from the current temperature and across from the current barometric pressure, the user obtains the corrected ballistic coefficient. The user then uses the compensated ballistic coefficient to index into a windage variable section of the windage compensation table 16 to obtain the appropriate windage variable. That indexing may be based on, for example, reading down from the ballistic coefficient and across from the muzzle velocity. That is, the windage variables may be arranged in row/column form by increasing (or decreasing) ballistic coefficient and increasing (or decreasing) muzzle velocity.
An example, for a 700 grain, .50 caliber full metal jacket bullet, the compensated ballistic coefficient portion of the windage compensation table might have the following structure and data:
|TABLE 1 |
|Exemplary Compensated Drag Coefficients for Nominal Drag |
|Coefficient of 0.66 |
|Barometric ||Temperature (degrees F) |
|Pressure ||−30 ||−20 ||−10 ||0 ||10 ||20 ||30 ||40 |
|19 ||0.850 ||0.869 ||0.889 ||0.909 ||0.929 ||0.949 ||0.968 ||0.988 |
|19.5 ||0.828 ||0.847 ||0.866 ||0.886 ||0.905 ||0.924 ||0.944 ||0.963 |
|20 ||0.807 ||0.826 ||0.845 ||0.864 ||0.882 ||0.901 ||0.920 ||0.939 |
|20.5 ||0.788 ||0.806 ||0.824 ||0.843 ||0.861 ||0.879 ||0.898 ||0.916 |
|21 ||0.769 ||0.787 ||0.805 ||0.822 ||0.840 ||0.858 ||0.876 ||0.894 |
|21.5 ||0.751 ||0.768 ||0.786 ||0.803 ||0.821 ||0.838 ||0.856 ||0.873 |
|22 ||0.734 ||0.751 ||0.768 ||0.785 ||0.802 ||0.819 ||0.836 ||0.853 |
|22.5 ||0.718 ||0.734 ||0.751 ||0.768 ||0.784 ||0.801 ||0.818 ||0.834 |
|23 ||0.702 ||0.718 ||0.735 ||0.751 ||0.767 ||0.784 ||0.800 ||0.816 |
|23.5 ||0.687 ||0.703 ||0.719 ||0.735 ||0.751 ||0.767 ||0.783 ||0.799 |
|24 ||0.673 ||0.688 ||0.704 ||0.720 ||0.735 ||0.751 ||0.767 ||0.782 |
|24.5 ||0.659 ||0.674 ||0.690 ||0.705 ||0.720 ||0.736 ||0.751 ||0.766 |
|25 ||0.646 ||0.661 ||0.676 ||0.691 ||0.706 ||0.721 ||0.736 ||0.751 |
|25.5 ||0.633 ||0.648 ||0.663 ||0.677 ||0.692 ||0.707 ||0.722 ||0.736 |
|26 ||0.621 ||0.635 ||0.650 ||0.664 ||0.679 ||0.693 ||0.708 ||0.722 |
|26.5 ||0.609 ||0.623 ||0.638 ||0.652 ||0.666 ||0.680 ||0.694 ||0.709 |
|27 ||0.598 ||0.612 ||0.626 ||0.640 ||0.654 ||0.668 ||0.681 ||0.695 |
|27.5 ||0.587 ||0.601 ||0.614 ||0.628 ||0.642 ||0.655 ||0.669 ||0.683 |
|28 ||0.577 ||0.590 ||0.603 ||0.617 ||0.630 ||0.644 ||0.657 ||0.671 |
|28.5 ||0.566 ||0.580 ||0.593 ||0.606 ||0.619 ||0.632 ||0.646 ||0.659 |
|29 ||0.557 ||0.570 ||0.583 ||0.596 ||0.609 ||0.622 ||0.634 ||0.647 |
|29.5 ||0.547 ||0.560 ||0.573 ||0.585 ||0.598 ||0.611 ||0.624 ||0.636 |
|30 ||0.538 ||0.551 ||0.563 ||0.576 ||0.588 ||0.601 ||0.613 ||0.626 |
|30.5 ||0.529 ||0.542 ||0.554 ||0.566 ||0.579 ||0.591 ||0.603 ||0.616 |
|31 ||0.521 ||0.533 ||0.545 ||0.557 ||0.569 ||0.581 ||0.594 ||0.606 |
|31.5 ||0.513 ||0.524 ||0.536 ||0.548 ||0.560 ||0.572 ||0.584 ||0.596 |
|32 ||0.504 ||0.516 ||0.528 ||0.540 ||0.551 ||0.563 ||0.575 ||0.587 |
From the above table, one obtains the appropriately compensated ballistic coefficient and then uses that coefficient and the target range to index into the next portion of the windage compensation table 16
, represented as Table 2, below:
|TABLE 2 |
|Exemplary Windage Variables for 2800 ft/s Muzzle Velocity |
|Target ||Compensated Ballistic Coefficients |
|Range ||0.53 ||0.55 ||0.57 ||0.59 ||0.61 ||0.63 ||0.65 ||0.67 ||0.69 ||0.71 ||. . . ||1.07 |
|500 ||14 ||15 ||17 ||17 ||17 ||17 ||18 ||20 ||20 ||20 ||. . . ||31 |
|600 ||13 ||15 ||16 ||16 ||17 ||17 ||18 ||18 ||20 ||20 ||. . . ||31 |
|700 ||13 ||14 ||16 ||16 ||16 ||17 ||18 ||18 ||18 ||20 ||. . . ||30 |
|800 ||13 ||13 ||15 ||15 ||16 ||16 ||18 ||18 ||18 ||20 ||. . . ||30 |
|900 ||13 ||13 ||14 ||14 ||15 ||15 ||16 ||17 ||18 ||18 ||. . . ||30 |
|1000 ||12 ||13 ||13 ||14 ||14 ||15 ||15 ||17 ||17 ||18 ||. . . ||29 |
|1100 ||12 ||12 ||13 ||14 ||14 ||15 ||15 ||16 ||17 ||17 ||. . . ||29 |
|1200 ||11 ||12 ||13 ||13 ||13 ||14 ||15 ||16 ||16 ||17 ||. . . ||29 |
|1300 ||11 ||11 ||12 ||12 ||13 ||14 ||14 ||15 ||15 ||16 ||. . . ||28 |
|1400 ||11 ||11 ||12 ||12 ||13 ||13 ||14 ||15 ||15 ||16 ||. . . ||2 |
|1500 ||10 ||11 ||12 ||12 ||13 ||13 ||14 ||14 ||15 ||16 ||. . . ||27 |
|1600 ||10 ||11 ||11 ||12 ||12 ||13 ||13 ||14 ||15 ||15 ||. . . ||26 |
|1700 ||10 ||11 ||11 ||12 ||12 ||13 ||13 ||14 ||14 ||15 ||. . . ||26 |
|1800 ||10 ||11 ||11 ||11 ||12 ||12 ||13 ||13 ||14 ||14 ||. . . ||25 |
|1900 ||10 ||10 ||11 ||11 ||12 ||12 ||13 ||13 ||14 ||14 ||. . . ||25 |
|2000 ||10 ||10 ||11 ||11 ||12 ||12 ||13 ||13 ||13 ||14 ||. . . ||24 |
From Table 2, one thus obtains the correct windage variable. Notably, those skilled the art will observe that, for a given bullet and given “nominal” ballistic coefficient, the windage variable as provided by the windage compensation table 16 changes as a function of temperature and/or pressure and thus incorporates a “built-in” correction for changes in predicted bullet drift. With such compensation, the aiming system 10 provides extremely precise windage hold-off values to the shooter. Those skilled in the art will further appreciate that the windage compensation table 16 may contain tabulated compensation and windage variable data for a variety of bullet weights/nominal coefficients and muzzle velocities, and that such organization complements both printed and electronically stored embodiments of windage compensation table 16.
In any case, after obtaining the correct windage variable from the windage compensation table 16, the user then enters it into the processing module 12 of the aiming system 10. In an exemplary embodiment, after entering the windage variable into the processing module, the user need only to enter the range to the target and adjust the speed of the wind-reading scope's translating indicia 34 to match that of the downrange mirage or moving target. The processing module 12 then determines the wind speed based on the translation rate of the indicia 34, and uses that value, the target range, and the windage variable to compute the hold-off value. As noted, the hold-off value may be provided to the user in mils, thus saving a conversion step and providing the shooter with a hold-off value that corresponds to the mils-based reticle markings appearing within the field of view of wind-reading scope 14.
Thus, exemplary hold-off value computation performed by aiming system 10
in accordance with the present invention may be expressed as,
where y equals the windage variable as obtained from the windage table 16, and where, in exemplary embodiments, the wind speed is obtained by or from the wind-reading scope 14, as was explained in the parent application and further detailed later herein. While the above details illustrate an exemplary windage table organization, those skilled in the art will recognize that other organizational schemes may be used for the data stored in the windage compensation table 16, and that different indexing logic may be needed accordingly.
Further, the windage compensation table 16 may be embodied in a variety of formats. For example, the windage compensation table may be embodied in one or more printed tables, as described in above and as shown in FIG. 1. If so, only a user in possession of the printed (or electronically stored) windage compensation table 16 can enter a valid windage variable into processing module 12 and, therefore, the precision aiming assistance provided by aiming system 10 is denied to would-be users not in possession of the windage compensation table 16.
As noted above, with the printed embodiment of windage table 16, a user would manually index into the tabulated windage variables to obtain the correct windage variable for his or her particular set of shooting parameters. With a valid windage variable thus obtained, the user enters the windage variable directly or indirectly into processing module 12, such as by keypad data entry, for computation of the proper windage hold-off value. Of course, such entry of the windage variable represents one of several exemplary scenarios for obtaining the windage variable at the processing module 12. FIG. 4 illustrates a general functional arrangement for the circuits comprising processing module 12, although those skilled in the art will appreciate that this exemplary arrangement may be varied as needed or desired without departing from the underlying functionality.
Here, processing module 12 comprises a processor circuit 70 to compute the hold-off value, an interface circuit 72 to receive or otherwise access the windage variable and thus enable computation of the hold-off value, and a scope interface 74, the functionality of which varies in dependence upon whether the scope 14 determines wind speed on its own, or whether the processing module determines wind speed based on the control inputs 18. That is, in at least one embodiment, the processing module 12 determines the wind-speed based on its knowledge of the translation rate of the indicia 34. Thus, where the user sights through the scope 14 and adjusts the indicia translation rate to match that of, say, a downrange wind mirage, the processing module 12 can thus infer the downrange crosswind speed. In other embodiments where the scope 14 is not communicatively coupled to the processing module 12, the scope interface 74 may be omitted.
FIG. 5 depicts exemplary details for processing module 12, wherein processor circuit 70 comprises a logic circuit 80 and program memory 82, and an optional memory circuit 84 stores windage compensation table 16 as an electronically stored look-up table accessed through interface circuit 72 configured as a memory interface circuit. Alternatively, interface circuit 72 comprises a user interface 86 that comprises a keypad interface 88 and a keypad 90, and a display interface 92 with an associated display 94. Further, an exemplary scope interface 74 comprises a processor interface 96, a data scope interface circuit 98, and a control circuit 100 that is associated with the wind-matching control input 18A and 18B.
The supporting program memory 82 generally includes computer instructions for implementing the present invention. With this arrangement, the logic circuit 80 might comprise a microprocessor, such as the 8-bit M68HC05 or 16-bit M68HC12 microprocessors from MOTOROLA, or the 16-bit MCS296 series of microprocessors from INTEL. Of course, the particular microprocessor chosen simply represents a design choice based on costs and needs, and it should be understood that wide variation is possible in this regard. Indeed, the processing module 12 and/or the electronics of scope 14 may be implemented using custom integrated circuits, such as one or more custom Application Specific Integrated Circuits (ASICS), Complex Programmable Logic Devices (CPLDs), and or Field Programmable Gate Arrays (FPGAs).
Moreover, it should be understood that many microprocessors intended for “embedded systems” use are available with a high level of support circuit integration, and that logic circuit 80 might be implemented as an integrated microprocessor. Such microprocessors typically are termed “microcontrollers” and it should be understood that the term microprocessor as used herein encompasses such highly integrated microcontrollers. Thus, logic circuit 80 might comprise an integrated microprocessor having its own memory, its own interface and control circuitry (digital I/O, analog-to-digital conversion and digital-to-analog conversion, Pulse Width Modulators (PWMs), timer/control circuits, etc.). In particular, a microprocessor-based timing control circuit in combination with digital bit I/O or memory mapped I/O represents an exemplary approach to controlling the translation rate of indicia 34.
Further, program memory 82 may comprise an integrated portion of logic circuit 80 and, if the interface circuit 72 is implemented as a memory interface circuit for accessing the windage compensation table 16 stored in memory circuit 84, it too may be integrated into logic circuit 80. Indeed, memory circuit 84 might be integrated into logic circuit 80. In an exemplary embodiment, whether integrated or not, memory circuit 84 comprises non-volatile, erasable memory, such as FLASH or EEPROM memory that can be loaded with windage compensation table 16.
Further, in embodiments where processing module 12 is integrated within the wind-reading scope 14, the microprocessor selected for logic circuit 80 may integrate display controller 50, and thus would provide both computation of the hold-off value as well as wind-speed determination and control of display 28. Those skilled in the art will appreciate the range of such implementation variations.
Regardless, where the processing module 12 receives the windage variable as data input by the user, the interface circuit 72 preferably includes the user interface 86 detailed above to support such data entry. It should be noted that the user might input other values via user interface 86 for use by processing module 12. For example, where the user enters the windage variable as data input to keypad 90, he or she might also enter a target range and, if the processing module 12 does not obtain wind speed from the wind-reading scope 14, the user might also key in a wind speed value.
In any case, with the defined set of parameters entered into processing module 12, or otherwise obtained by it, processor circuit 70 determines a precision hold-off value for the user according to, for example, Equation (2) as presented earlier herein. In that sense, then, processing module 12 may be programmed to operate in a standby mode until it receives all in a defined set of parameters needed for computation of the hold-off value, and further programmed to transition to operation in an active mode, wherein it computes the hold-off value, responsive to receiving all of the required parameters. As such, the precision aiming assistance provided by the aiming system 10 is denied unless the user provides the processing module with the required windage variable or otherwise enables it to access such information.
In other variations, the processing module 12, whether or not integrated into scope 14, might be outfitted with one or more parameter sensors, such as shown in FIG. 6. With this arrangement, the processing module 12 obtains one or more of the parameters required for computation of the hold-off value without need for direct data input by the user or from another source. For example, the processor circuit 70 might be communicatively coupled to one or all of an ambient pressure sensor 102, a temperature sensor 104, and a ranging sensor 106.
FIG. 7 illustrates another exemplary embodiment of aiming system 10, wherein the aiming system 10 further includes a security module 110. In one embodiment, the security module 110 provides the processing module an authorization value in the form of an authorization code. Receipt of a valid code by the processing module 12 enables it to access memory circuit 84 and thereby obtain the correct windage variable from its locally stored copy of windage compensation table 16. In another embodiment, the authorization value sent from the security module 110 to the processing module 12 is the windage variable, although it may be in an encoded form.
With that latter embodiment, the security module 110 includes a locally stored copy of the windage compensation table 16. Thus, an exemplary embodiment of the security module 110 comprises a logic circuit 112, e.g., a microprocessor circuit, a user interface 114, a memory circuit 116, and a transmitter circuit 118.
With this arrangement, the user still might be required to enter an authorization code into the security module 110 to thereby enable access to the stored windage compensation table 16 and subsequent transmission of the windage variable to the processing module 12. Further, the user may be required to enter other parameters as needed, such as pressure, temperature, muzzle velocity, target range, etc., such that the logic circuit 112 is able to properly index into the stored windage compensation table 16 and obtain the correct windage variable.
Transmit circuit 118 may be designed for wired or wireless coupling to processing module 12. In an exemplary embodiment, transmission is wireless and may be optical, but transmit circuit 118 is preferably implemented as a short-range radio frequency transmitter for transmitting data to the processing module 12.
As such, one embodiment of security module 110 simply functions as a “black box” that must be nearby to processing module 12 to enable computation of the windage variable. That is, in one embodiment of aiming system 10, the processing module 12 would not compute the hold-off value, or at least would not make it available for use, unless it received the require enabling signal(s) from the security module 110.
It would not be necessary for these enabling signals to convey the windage variable, as that value might be entered by the user or contained in the processing module 12. Rather, such enabling signals would serve as an additional level of security by preventing use of the aiming system to a user that had somehow obtained access to the windage variable but lacked the correct security module 110. As such, individual security modules 110 could be “keyed” to particular aiming systems 10, such that the security module 110 for a particular aiming system 10 would enable only that aiming system 10. In this manner, a sniper could be issued a specific security module 110 and only the aiming system 10 assigned to that sniper would be activated by his or her security module 110.
Regardless, it should be understood that the security module 110 can be varied as needed or desired. For example, the security module 110 might include one or more parameter sensors, e.g., pressure, temperature, range, etc., such that it automatically determines one or more of the parameters needed to either index into the windage compensation table 16, and/or to compute Equation (2) above.
Thus, in one or more of the exemplary embodiments described above, the aiming system 10 operates as a selectively enabled aiming system that provides security features in the sense that it remains in a standby mode until all required parameters are available. As one of the primary parameters required for computation of the windage hold-off value is the windage variable, aiming assistance is not provided unless a valid windage variable is available. FIG. 8 thus provides an exemplary illustration of operating logic for aiming system 10 that is consistent with its secure operation.
Assuming that aiming system 10 is “on” and in standby mode (a default mode in one exemplary embodiment), processing begins with receipt of a parameter required for computation of the hold-off value (Step 200). If the received parameters is not the last one needed (Step 202), the processing module 12 remains in standby mode awaiting the receipt of all required parameters (Steps 204 and 202).
If all needed parameters are received or otherwise available in processing module 12, processing continues with optional decoding and validation of the windage variable or, more generally, an authorization value (Steps 206 and 210). For example, where the processing module 12 receives an authorization value from the security module 110 as an electromagnetic signal, the processing module 10 may decode the received value, such as by performing a CRC or cryptographic check, and/or validate the received value, such as by performing a bounds check or other “sanity” check on the value.
After completing or otherwise skipping such procedures, processing continues with the processing module 12 transitioning into active mode (Step 212). In active mode, the processing module 12 computes the hold-off value, preferably by using the windage variable, the wind speed, and the target range (Step 214), and then displays or otherwise makes the hold-off value available to the user (Step 216). Making the hold-off value available to the user may comprise displaying a numeric value, such as a MOA or a mils hold-off value and left/right direction on display 18, and/or, if processing module 12 is communicatively coupled to wind-reading scope 14, transferring the hold-off information to scope 14 for viewing on display 28. Note that, depending on the interface details, the hold-information may be transferred to the scope as data or as corresponding control signal information. For example, the data might be converted into a display driver control signal.
However, those skilled in the art will appreciate that such signal details are not germane to the broader inventive concepts of the present invention. Indeed, the present invention generally provides precision aiming assistance on a selective basis. The windage compensation table that enables computation of the hold-off value provided by the aiming system 10 may be stored in the form of printed tables for manual input into the processing module 12 (or security module 110), or may be stored electronically in look up table form (again in the processing module 12 or in the security module 110). As such, the present invention is not limited by the foregoing discussion and its accompanying drawings, but rather is limited only by the following claims and the reasonable equivalents thereof.