U.S. patent application number 10/365022 was filed with the patent office on 2004-02-05 for method and apparatus to provide precision aiming assistance to a shooter.
Invention is credited to Osborn, John H. II.
Application Number | 20040020099 10/365022 |
Document ID | / |
Family ID | 46298989 |
Filed Date | 2004-02-05 |
United States Patent
Application |
20040020099 |
Kind Code |
A1 |
Osborn, John H. II |
February 5, 2004 |
Method and apparatus to provide precision aiming assistance to a
shooter
Abstract
An aiming system provides precision aiming assistance to a user
based on the availability of a windage variable that is used in the
computation of a windage hold-off. In an exemplary embodiment, the
aiming system comprises a processing module, a wind-reading scope,
and a windage compensation table comprising tabulated windage
variables. In one or more other embodiments, the aiming system
further comprises a security module, which may be used to store the
windage compensation table in electronic form, store an
authorization code, or otherwise serve as an enabling device for
operation of the aiming system. Regardless, unless a valid windage
variable as obtained from the windage compensation table is made
available to the processing module, the aiming system does not
compute a precision hold-off. If the windage variable is available,
along with any other needed parameter, such as target range and
wind speed, the processing module computes the hold-off value.
Inventors: |
Osborn, John H. II;
(Franklinton, LA) |
Correspondence
Address: |
COATS & BENNETT, PLLC
P O BOX 5
RALEIGH
NC
27602
US
|
Family ID: |
46298989 |
Appl. No.: |
10/365022 |
Filed: |
February 12, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10365022 |
Feb 12, 2003 |
|
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09805608 |
Mar 13, 2001 |
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Current U.S.
Class: |
42/122 |
Current CPC
Class: |
F41G 1/38 20130101; F41G
1/473 20130101 |
Class at
Publication: |
42/122 |
International
Class: |
F41G 001/38 |
Claims
What is claimed is:
1. An aiming system to provide aiming assistance to a shooter
comprising: 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 comprising: an interface circuit to receive
the windage variable; and a processor circuit programmed to compute
a hold-off value for the wind-reading scope based on at least the
wind speed and the windage variable.
2. The aiming system of claim 1, wherein the processor circuit does
not enter an active mode, in which the processor computes the
hold-off value, unless the windage variable is received, and
otherwise remains in a standby mode, wherein the hold-off value is
not computed.
3. The aiming system of claim 2, wherein the processor circuit
standby and active modes comprise a security feature whereby the
aiming system denies aiming point assistance to a user of the
aiming system unless a windage variable is received by the
processor circuit.
4. The aiming system of claim 1, wherein the windage compensation
table comprises one or more printed tables, and wherein the
interface circuit includes a user interface to receive the windage
variable as data input by a user of the shooting system having
access to the one or more printed tables.
5. The aiming system of claim 4, wherein the user interface
comprises a keypad to receive the windage variable as keypad inputs
from the user.
6. The aiming system of claim 5, wherein the processor circuit
computes the hold-off value further based on one or more additional
parameters, including a target range, and wherein the processor
circuit is programmed to at least the target range as additional
keypad inputs from the user.
7. The aiming system of claim 1, wherein the processor circuit is
programmed to compute the hold-off value based on a defined set of
parameters including the wind speed, the windage variable and a
target range.
8. The aiming system of claim 7, wherein the processor circuit is
programmed to operate in a standby mode until all of the parameters
in the defined set of parameters are received, and then, responsive
to receiving a last one of the defined parameters, to transition to
an active mode in which the processor circuit computes the hold-off
value.
9. The aiming system of claim 1, further comprising a security
module communicatively coupled to the processing module to
authorize computation of the hold-off value.
10. The aiming system of claim 9, wherein the security module
comprises: a transmitter circuit to transmit an authorizing value
to the processing module, wherein the authorizing value enables
computation of the hold-off value by the processor circuit; and a
logic circuit to provide the authorizing value to the transmitter
circuit.
11. The aiming system of claim 10, wherein the processing module
further comprises a receiver circuit communicatively coupled to the
processor circuit to receive the authorizing value from the
security module.
12. The aiming system of claim 11, wherein the authorizing value
comprises the windage variable, and wherein the logic circuit
within the security module includes a memory circuit to store the
windage compensation table.
13. The aiming system of claim 11, wherein the authorizing value
comprises an authorization code, and further wherein the processing
module includes a memory circuit to store the windage compensation
table, and wherein the processor circuit is programmed to access
the memory circuit responsive to receiving a valid authorization
code.
14. The aiming system of claim 1, wherein the interface circuit
comprises a memory interface circuit associated with the processor
circuit, and wherein the processing module further comprises: a
memory circuit to store the windage compensation table; and a user
interface to receive an authorization code from a user of the
aiming system; said processor circuit programmed to obtain the
windage variable from the memory circuit responsive to receiving a
valid authorization code from the user.
15. The aiming system of claim 14, wherein the processor circuit is
programmed to obtain the windage variable from the stored windage
compensation table by indexing into the table based on at least one
or more defined parameters, including a target range, a muzzle
velocity, an ambient temperature, and an ambient pressure.
16. The aiming system of claim 1, wherein the processor circuit is
programmed to compute the hold-off value based on a defined set of
parameters including the windage variable, the wind speed, and a
target range.
17. The aiming system of claim 16, wherein the defined set of
parameters further includes a muzzle velocity, and at least one of
an ambient temperature and ambient pressure.
18. The aiming system of claim 17, wherein the interface circuit
comprises a user interface to receive at least one of the
parameters in the defined set of parameters as data input by a user
of the aiming system.
19. The aiming system of claim 18, further comprising one or more
parameter sensors to determine one or more of the parameters in the
defined set of parameters, such that one or more parameters are
received as data input by the user via the user interface, and one
or more parameters are determined by the one or more parameter
sensors.
20. The aiming system of claim 1, wherein the processor circuit
receives an encoded windage variable, and wherein the processor
circuit is programmed to decode the encoded windage variable to use
in computing the hold-off value.
21. The aiming system of claim 1, further comprising a scope
interface circuit communicatively coupling the processing module
and the wind-reading scope.
22. The aiming system of claim 21, wherein the processing module
determines the wind-speed by controlling a wind-reading function of
the wind-reading scope.
23. The aiming system of claim 21, wherein the processing module
receives the wind speed as determined by the wind-reading
scope.
24. The aiming system of claim 21, wherein the processing module
provides the wind-reading scope with the hold-off value or with a
control signal corresponding to the hold-off value.
25. The aiming system of claim 24, wherein the wind-reading scope
displays an indicia corresponding to the hold-off value or control
signal received from the processing module within a field of view
provided by the wind-reading scope.
26. The aiming system of claim 1, wherein the wind-reading scope
displays wind-matching indicia having an adjustable translation
speed and an adjustable translation direction relative to a field
of view provided by the wind-reading scope, and wherein the
wind-matching indicia are responsive to one or more adjustment
controls included as part of the aiming system, thereby allowing a
user to determine wind speed by matching the translation speed and
direction of the wind-matching indicia to actual wind conditions as
observed through the field of view.
27. The aiming system of claim 26, wherein the wind-reading scope
includes a data interface communicatively coupled to the processing
module.
28. The aiming system of claim 27, wherein the adjustment controls
comprise part of the processing module, and wherein the processing
module controls the wind-matching indicia responsive to user
operation of the adjustment controls.
29. The aiming system of claim 27, wherein the adjustment controls
comprise part of the wind-reading scope.
30. The aiming system of claim 27, wherein the wind-reading scope
determines the wind-speed based on the translation speed of the
wind-matching indicia and transfers a corresponding wind speed
value to the processing module.
31. The aiming system of claim 1, wherein the processing module
computes the hold-off value in mils.
32. The aiming system of claim 31, wherein the wind-reading scope
displays the computed hold-off value as a mils-based offset
indicator.
33. An aiming system to provide aiming assistance to a shooter
comprising: a processing module to compute a hold-off value to
assist aiming by a shooter based on a defined set of parameters,
including at least a windage variable and a wind speed; said
processing module operating in a standby mode if less than all of
the defined parameters are available for computing the hold-off
value, and operating in an active mode if all of the defined
parameters are available, including a valid windage variable, and
wherein the processing modules computes the hold-off value in the
active mode; and a windage compensation table to provide a valid
windage variable and thereby enable computation of the hold-off
value, and wherein the windage table is based on ballistic
coefficients compensated for at least one of an ambient temperature
and an ambient pressure.
34. The aiming system of claim 33, further comprising a
wind-reading scope to obtain the wind speed.
35. The aiming system of claim 34, wherein the wind-reading scope
is communicatively coupled to the processing module, and wherein
the wind-reading scope provides the wind speed under control of the
processing module.
36. The aiming system of claim 33, wherein the windage compensation
table comprises one or more printed tables and wherein the
processing module includes a keypad for entry of the windage
variable.
37. The aiming system of claim 33, wherein the aiming system
further comprises a security module for transmitting an authorizing
value to the processing module, and wherein the processing module
further comprises a receiver circuit to receive the authorizing
value.
38. The aiming system of claim 37, wherein the processing module
receives the windage variable as the authorizing value.
39. The aiming system of claim 37, wherein the processing module
receives an authorization code as the authorizing value, and
wherein the processing module does not compute the hold-off value
unless a valid authorization code is received from the security
module.
40. A method of providing aiming assistance to a shooter
comprising: operating an aiming system in a standby mode if a valid
windage variable is not available, and wherein no aiming assistance
is provided to a user of the aiming system in standby mode;
operating the aiming system in active mode if a valid windage
variable is available, and wherein a hold-off value is provided to
the user as aiming assistance in the active mode; and in active
mode: obtaining 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
computing the hold-off value based on a defined set of parameters
that includes the valid windage variable.
41. The method of claim 40, wherein the windage table comprises one
or more printed tables, and wherein obtaining a valid windage
variable comprises receiving the valid windage variable as data
input by a user of the aiming system.
42. The method of claim 40, wherein the windage compensation table
comprises a look-up table stored in a memory circuit, and wherein
obtaining a valid windage variable is based on accessing the stored
look-up table.
43. The method of claim 42, wherein the aiming system includes a
processing module that includes the memory circuit, and wherein
obtaining a valid windage variable comprises the processing module
accessing the stored look-up table responsive to receiving an
authorization code.
44. The method of claim 43, wherein receiving an authorization code
comprises receiving data input from a user of the aiming
system.
45. The method of claim 43, wherein the aiming system further
comprises a security module communicatively coupled to the
processing module, and wherein receiving an authorization code
comprises receiving the authorization code from the security
module.
46. The method of claim 45, wherein receiving the authorization
code from the security module comprises receiving a wireless signal
from the security module.
47. The method of claim 42, wherein the aiming system includes a
processing module to compute the hold-off value, and a security
module that includes the memory circuit to store the look-up table,
and wherein obtaining a valid windage variable comprises accessing
the stored look-up table to obtain the windage variable and
transferring the windage variable from the security module to the
processing module.
48. The method of claim 47, further comprising accessing the stored
look-up table at the security module responsive to receiving an
authorization code input by a user of the security module.
49. The method of claim 40, wherein operating an aiming system in a
standby mode it a valid windage variable is not available comprises
remaining in standby mode until all of the defined set of
parameters are available, including the windage variable.
50. The method of claim 49, wherein operating the aiming system in
active mode if a valid windage variable is available comprises
transitioning from standby mode to active mode and computing the
hold-off value responsive to all of the defined parameters,
including the windage variable, becoming available.
51. The method of claim 49, wherein the defined parameters include
a wind speed, a target range, the windage variable, and at least
one of an ambient temperature and an ambient pressure.
52. The method of claim 51, further comprising obtaining the wind
speed from a wind-reading scope.
53. The method of claim 52, wherein obtaining the wind speed from a
wind-reading scope comprises matching a speed and a direction of
translating indicia displayed within a field of view of the
wind-reading scope to actual wind conditions as observed through
the wind-reading scope.
54. The method of claim 53, further comprising providing the
hold-off value or a control signal corresponding to the hold-off
value to the wind-reading scope to provide aiming assistance within
the field of view of the wind-reading scope.
Description
RELATED APPLICATIONS
[0001] The present invention claims priority under 35 U.S.C. .sctn.
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.
BACKGROUND OF THE INVENTION
[0002] The present invention generally is related to shooting, and
particularly is related to providing aiming assistance for
precision shooting at extended distances.
[0003] 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.
[0004] 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.
[0005] 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.
[0006] 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."
[0007] 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.
[0008] 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.
[0009] 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.
SUMMARY OF THE INVENTION
[0010] 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.
[0011] 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.
[0012] 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.
[0013] 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.
[0014] 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.
[0015] 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.
[0016] 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.
[0017] 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.
[0018] 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.
[0019] 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.
[0020] 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.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a diagram of an exemplary aiming system according
to the present invention.
[0022] FIG. 2 is a diagram of an exemplary field-of-view display
for a wind-reading scope of an exemplary aiming system.
[0023] FIG. 3 is a cutaway diagram of an exemplary display
arrangement for the wind-reading scope.
[0024] FIG. 4 is a diagram of an exemplary functional arrangement
for a processing module of an exemplary aiming system.
[0025] FIG. 5 is a diagram of exemplary details of the processing
module.
[0026] FIG. 6 is a diagram of additional exemplary details of the
processing module.
[0027] FIG. 7 is a diagram of exemplary details for the aiming
system, including a security module.
[0028] FIG. 8 is a diagram of exemplary operating logic for the
aiming system.
DETAILED DESCRIPTION OF THE INVENTION
[0029] 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.
[0030] 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.
[0031] 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.
[0032] 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.
[0033] 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.
[0034] 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.
[0035] 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.
[0036] 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.
[0037] 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.
[0038] In contrast, conventional ballistic processing bases wind
effect computations on fixed windage factors, which may be
expressed as, 1 x = Wind speed .times. Range A , ( 1 )
[0039] 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.
[0040] 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.
[0041] 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.
[0042] 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.times.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.
[0043] 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.
[0044] 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.
[0045] 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.
[0046] 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.
[0047] 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:
1TABLE 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
[0048] 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:
2TABLE 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
[0049] 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.
[0050] 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.
[0051] Thus, exemplary hold-off value computation performed by
aiming system 10 in accordance with the present invention may be
expressed as, 2 x = Wind speed .times. Range y , ( 2 )
[0052] 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.
[0053] 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.
[0054] 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.
[0055] 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.
[0056] 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.
[0057] 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).
[0058] 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.
[0059] 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.
[0060] 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.
[0061] 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.
[0062] 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.
[0063] 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.
[0064] 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.
[0065] 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.
[0066] 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.
[0067] 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.
[0068] 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.
[0069] 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.
[0070] 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.
[0071] 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.
[0072] 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).
[0073] 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.
[0074] 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.
[0075] 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.
* * * * *