US3778059A

US3778059A - Automatic gunnery shock wave scoring apparatus using metallic conductors as shock wave sensors

Info

Publication number: US3778059A
Application number: US00184605A
Authority: US
Inventors: G Rohrbaugh; F Bamser
Original assignee: Singer Co
Current assignee: Singer Co
Priority date: 1970-03-13
Filing date: 1971-09-28
Publication date: 1973-12-11
Anticipated expiration: 1990-12-11

Abstract

An automatic gunnery scoring system responsive to the airborne acoustic shock wave produced by a projectile such as a bullet or the like as it passes through a target area and comprising mutually perpendicular elongated acoustic energy conductors located adjacent the perimeter of the target with one or more acoustic transducers attached to an end or ends thereof, but no more than one on each end, for producing an electrical signal when the shock wave from the projectile is transmitted thereto through the respective conductor means. Four electrical signals are thus produced which are fed to electronic circuitry to determine the location of each ''''hit'''' on the target in rectangular coordinates and providing a suitable indication thereof.

Description

United States Patent 1191 Rohrbaugh et al.

1451 Dec. 11, 1973 AUTOMATIC GUNNERY SHOCK WAVE SCORING APPARATUS USING METALLIC CONDUCTORS AS SHOCK WAVE SENSORS [75] Inventors: George W. Rohrbaugh; Frank G.

Bamser, Jr., both of State College,

[21] Appl. No.: 185,605

Related US. Application Data [63] Continuation of Ser. No. 19,324, March 13, 1970,

3,158,372 ll/l964 Ohlund ..273/l02.2S

Primary Examiner-Richard C. Pinkham Assistant Examiner-Marvin Siskind AttrneyMarshall J. Breen et al.

[57] ABSTRACT An automatic gunnery scoring system responsive to the airborne acoustic shock wave produced by a projectile such as a bullet or the like as it passes through a target area and comprising mutually perpendicular elongated acoustic energy conductors located adjacent the perimeter of the target with one or more acoustic transducers attached to an end or ends abandoned.

thereof, but no more than one on each end, for pro- 52 us. Cl. 273/1021 s 340/16 35/25 dueihg ah eleehiee' Signal when the eheek Wave from 51] 110.01 F4ij 5/00 the Pheieehle is transmitted there) thheugh the [58] Field of Search U 273/1022 R 02.2 spective conductor means. Four electrical signals are 340/16 35/25 thus produced which are fed to electronic circuitry to determine the location of each hit on the target in [56] References Cited rectangular coordinates and providing a suitable indi- UNITED STATES PATENTS there 3,022,076 2/1962 Zito 273/1021 S 15 Claims, 6 Drawing Figures a: 1 Y P 64 VERTICAL HIT l l'N"WAVE (ACOUSTIC SHOCK DOWN LOCATION FROM 1 1 WAVE mom: 6 CENTER 1 I i 42 6 X a I 14 N H l i & j, 11, um J70 72/ l y l K K CLOCK a BINARY I i 1 GATE COUNTER J0 R l 14* l N" WAVE i l 1 l A22 i 26 T #18 H2 L i IUFS .'n fl p I, m i

RIGHT 1 my PREAMP B2 11001101111111" I I mam 10011101111100 1 11 84 CENTER II ll i i LEFT PREAMP l1 4 $4M {LU 1 I1 CLOCK RESET AUTOMATIC GUNNERY SHOCK WAVE SCORING APPARATUS USING METALLIC CONDUCTORS AS SHOCK WAVE SENSORS The present application is a continuation application based upon our copending application Ser. No. 19,324 filed Mar. 13, 1970 and now abandoned.

BACKGROUND OF THE INVENTION l. Field of the Invention This invention relates to signaling apparatus for scoring gunnery target practiceand pertains more particularly for means for producing an electrical signal in response to a hit upon a target whereby indications of the results of firing are made available ata remote location.

2. Description of the Prior Art Learning to handle and shoot a firearm such as a rifle is important not only for military and police personnel, but also for the recreational gunner as well. This is commonly done on a firing range or course where fixed or moving targets are displayed to each gunman. The weapons and shooting techniques have changed with advancing technology, but the object of htting the target remains the same; although modern weapons are available, the old methods of scoring are still in widespread use, but are nevertheless inefficient.

One known present technique uses target spotters whichare slowfinaccurate and unreliable. Because of the time required to score each shot, multishot groups rather than individual rounds are scored. Moreover on rapid fire shooting sequences, round-for-round scoring is impossible. Spotter prejudice may further undermine the shooters results by a dishonest or lazy pit crew. With the need for spotters coupled together with the lag between shot and score, both manpower efficiency and training effectiveness and/or pleasure are reduced. The lack of immediate feedback to either the shooter or an observer as rounds are fired limit the entire procedure.

Although automatic scoring target courses where impack. vibration sensors detect silhouette hits are known, reliability in particular is needed. High speed, small caliber projectiles are missed by the silhouette sensors because of the low amplitude vibrations on bullet impact. Increasing the sensitivity of the vibration sensors only increases the probability of false triggering due to wind, etc. Also electrical contact methods are known but these systems, while being quite sensitive, suffer from inaccuracy and destructability.

The following patents are hereby referenced as being typical of the known priorart:

U.S.;Pat. No. 2,916,289 R. Zito Pat. No. 2,925,582 1. I. Mattei, et al.

. Pat. No. 2,934,346 T. Mongello Pat. No. 2,973,964 R. Zito Pat. No. 3,022,076 R. Zito Pat. No. 3,217,290 U. C. I. Sillman .iPat. No. 3,392,979 N. G. Wilska Pat. No. 3,479,032 .I. A. l. Ohlund, et al.

SUMMARY Briefly, the subject invention is directed to an improved automatic scoring target comprising a plurality of elongated acoustic energy conductor means positioned mutually perpendicularly to one another around the perimeter of a gunnery target area so as to be substantially parallel with the edges thereof when the target comprises a quadrilateral configuration and defining a common plane with the face thereof. Four acoustic transducers are attached to the acoustic energy conductor means, being attached to the ends thereof, and selectively located near the extremities or corners of the target. The transducers operate in pairs and are responsive to acoustic shock waves transmitted in the conductor means after having been struck by the airborne acoustic shock wave radiated as a supersonic projectile passes through the target producing respective electrical signals which are coupled to electronic circuit means which measure the time relationship between respective pairs of electrical signals from the transducers and indicate the location of the hit away BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram partially in block diagrammatic form illustrative of the preferred embodiment of the subject invention;

FIG. 2 is a cross-sectional view of an embodiment of one acoustic energy conductor utilized by the subject invention;

FIG. 3 is a fragmentary side elevational view of the embodiment of the acoustic energy conductor shown in FIG. 2;

FIG. 4 is a cross-sectional view of a second embodiment of an acoustic energy conductor utilized by the subject invention;

FIG. 5 is a cross-sectional view of still another embodiment of an acoustic energy conductor adapted for use by the subject invention; and

FIG. 6 is a diagram partially in block diagrammatic form illustrative of a second embodiment of the subject invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is based upon the principle that a projectile or bullet exceeding the speed of sound creates an acoustic shock wave which expands away from the line of flight of the bullet. As the bullet moves, the shock wave appears as an expanding cone. This high energy, fast rising ballistic shock wave front called the N wave can be detected by acoustic transducers which include means such as piezoelectric devices which operate to produce an electrical signal in response to the incidence of the acoustic shock wave.

Directing attention now to the preferred embodiment of the subject invention, FIG. 1 discloses a gunnery target 10 having a quadrilateral configuration in combination with first and second acoustic energy conductor means comprising in this embodiment a first and a second elongated

sonic energy conductor

12 and 14 having linear dimensions substantially equal to the width and length respectively of the target 10 and being located adjacent the perimeter thereof substantially parallel to the edges of the face of the target. The center 16 of the target 10 defines the intersection of an X and a Y axis of a rectangular coordinate system. The midpoint 18 of the conductor 12 is placed coincident with the Y axis while the mid-point 20 of the conductor 14 is placed coincident to the X axis. A first and a

second piezolectric transducer

22 and 24 are mounted on the ends of the acoustic conductor 12 while a third and a

fourth piezolectric transducer

26 and 28 are respectively mounted on the ends of the acoustic conductor 14.

Before proceeding to a description of the operation of the configuration thus far described, attention is first directed to FIGS. 2 through which are illustrative of three embodiments of the acoustic energy conductors l2 and 14. FIGS. 2 and 3 disclose a first embodiment of the acoustic conductor 12, it being understood that the identical explanation applies also to the acoustic conductor 14. This first embodiment consists of a solid metallic rod 30 composed, for example, of stainless steel, aluminum or the like preferably centrally aligned with a plane defined by the target 10. This is shown in FIG. 2. In order to protect the metallic rod 30 from bullets or projectiles fired at the target 10, a channel member 32 including a protective shield or metal deflector barrier 33 partially surrounds the rod 30 while leaving the portion adjacent target unobstructed. The metallic rod 30, moreover, is removably held in the channel member 32 by means of an acoustical isolation and damping material 34 which is preferably comprised of material manufactured under the tradename Velcro. This material is well known for a variety of uses but not as an acoustical dampener. This material furthermore is discussed in detail in U.S. Pat. No. 2,717,437.

A second embodiment of suitable acoustic conductor means comprises simply a thin flat strip of metal 36 p0- sitioned in the plane of the target 10 so that one surface for example its larger surface is disposed towards and aligned with the edge of the target 10. It should also be noted that the metallic strip 36 is intended to be mounted in a suitable protective barrier in a manner similar to that shown with respect to the embodiment disclosed in FIGS. 2 and 3. When desirable, the thin strip 36 as shown in FIG. 4 may be eliminated in favor ofa small diameter wire similarly located. Another embodiment of acoustic conduction means adapted for use with the subject invention is shown in FIG. 5 and comprises a hollow tube 38 filled with an acoustic energy conducting liquid 40.

The embodiments of the conductors shown in FIGS. 2 and 4 are based upon the fact that the speed of sound in metal is in the order of times that in air. For example, the speed of sound in air is approximately 1130 feet/sec. while the speed of sound in stainless steel is in the order of 16,660 feet/sec. The embodiment shown in FIG. 5, on the other hand, is based upon the fact that the liquid 40 selected also conducts acoustic energy at a relatively greater speed than that of air. Thus the respective transducers will be struck by secondary acoustic shock waves traveling in the acoustic conductors before the primary acoustic shock wave itself arrives thereto.

Returning now to the preferred embodiment of the subject invention shown in FIG. 1, reference numeral 42 designates a bullet or a projectile hit" on the target 10. The airborne primary acoustic shock wave N" appears as an expanding circle radiating outwardly from the hit 42 in the plane of the target. In the embodiment shown, the wave front first strikes the longitudinal acoustic conductor 14 at a distance H above the X axis. Faster traveling secondary acoustic shock waves are generated in the conductor 14 which move in mutually opposite directions along the conductor impinging first on the acoustic transducer 28 and then on the acoustic transducer 26 at a time later. The difference between the times that the respective secondary acoustic shock waves strike the

transducers

28 and 26 is a measure of the distance of the hit above the X axis. If the respective secondary wave strikes or impinges on the acoustic transducer 26 first, the hit will be known to be below the X axis. In a similar manner, the Nwave front strikes the horizontally oriented acoustic conductor 12 at wave distance L from the Y axis causing secondary acoustic shock waves to move toward the two

transducers

22 and 24. The difference in times that the secondary waves strike the

respective transducers

22 and 24 resulting from the N wave striking the rod 12 is a measure of the distance of the hit away from the Y axis. By determining which of the acoustic transducers is activated first determines upon which side of the Y axis the hit 42 occurred.

The embodiment shown in FIG. 1 additionally discloses electronic circuitry coupled to the

transducers

22, 24, 26'and 28 for determining the location of the hit in X-Y coordinates and displaying the miss distance both horizontally and vertically from the center 16 of the target 10 as well as giving an indication as to whether the hit 42 is up or down, left or right of center. This is accomplished by the circuitry 44 consisting of a subassembly 46 for the Y axis and an identical subassembly 48 for the X axis. The Y axis subassembly 46 is coupled to the

acoustic transducers

26 and 28 which are below the above center 16 by means of

respective signal preamplifiers

50 and 52. The signal preamplifier 50 designated the down preamplifier is coupled into a first level detector circuit 54 which may be for example a Schmitt trigger circuit while the output of the preamplifier 52 designated the up preamplifier is fed into a second level detector circuit 56. A level detector such as a Schmitt trigger circuit is well known to those skilled in the art and operates to provide a constant level signal output when the input thereto exceeds a predetermined input amplitude level or threshold but producing no output for a signal having an amplitude below the predetermined threshold. The

level detector circuits

54 and 56 have their respective outputs coupled into a control circuit 58 which is activated by which ever

level detector circuit

54 and 56 first receives a signal from its

respective transducers

26 and 28 and is deactivated when the other level detector circuit couples its output thereto. The control circuit 58 then acts as a start-stop" circuit providing an indication and an output gate the pulse width of which is a function of the difference in arrival times for the respective secondary acoustic shock waves at the

transducers

26 and 28. The control circuit 58 additionally includes output circuit leads 60 and 62 which are coupled to

indicator lights

64 and 66 to indicate which of the outputs occurred first in time thereby giving an indication as to whether the hit 42 is up" or down" from the center 16 of the target.

A crystal controlled clock or oscillator 68 provides a reference frequency output signal which is fed to one input of a clock gate circuit 70 which comprises a coincidence gate having its other input coupled to the output of the control circuitry 58. As long as the gate signal from the control circuitry 58 appears at the clock gate 70 the reference frequency from the crystal controlled clock 68 is fed into a binary counter circuit 72 which provides a signal, the total number of full cycles occurring in that interval being an accurate measure of the distance H. The output of the binary counter 72 is fed into a suitable indicator means 74 which provides a visual indication of the numerical value of the distance Habove or below target center. By selecting the crystal frequency such that the ratio of sound velocity in the acoustic conductors to the crystal frequency is H5 or 1/50 etc. the numerical value on the indicator will read directly in 0.1 inches or 0.01 inches, respectively etc. without the need for unit conversion or calculation. A manual rest button 76 is coupled from a point of reference potential to the control circuitry 58, the binary counter 72 and the indicator means 74 in order to reset the subassembly 46 for the next round to be fired at the target 10. It should be pointed out, however, when desirable automatic reset of the assembly 46 can be obtained byasimple modification of the control circuitry 58 and thereby provide a continuous indication for continuous or rapid firing.

The distance H from the X axis can be expressed by the. following equation:

Where T T is the difference in arrival times for the respective secondary shock waves at the

transducers

26 and 28 respectively, the V is the velocity of sound in the elongated acoustic conductor 14. Note that the length of the rod does not appear in the equation, thus expansion and contraction of the rod due to temperature changes will have no effect on accuracy. What is significant, however, is that mechanical alignment of the sonic conductor 14 with the adjacent edge of the target as to parallelism is significant as well as. the reference frequency of the crystal controlled clock 68. Where stainless steel is utilized for the elongated sonic conductor 14, the velocity change pro duced by temperature range from 10 C to 50 C is insignificant and the distance H is only a function of the accuracy of the timing circuitry.

Considering the X axis subassembly 48, it is identical to the Y subassembly 46 regarding the circuitry included and receives electrical signals from the

transducers

22 and 24 by means of right" and left

signal preamplifiers

78 and 80, respectively. The crystal controlled oscillator or clock 68 is also coupled to the X axis subassembly 48 which also includes level detector circuits, a control circuit as describedwith respect to theX axis subassembly 46. The subassembly 48 additionally includes a left and a

right indicator lamp

82 and 84 which indicates which of the

acoustic transducers

22 and 24 are first responsive to secondary acoustic shock waves traveling in the elongated conductor 12. A clock gate circuit and a binary counter, not shown, are also included the latter being coupled to a visual indicator means 86 which provides a numerical indication of the hit distance L away from target center. It should be pointed out that the visual indicator means 74 and 86 can be of any desired configuration. Nixie? tubes may be employed when desirable to provide a digital decimal indication of the X and Y coordinates of the hit 42. However, it should be noted that the binary counter outputs of the Y and

X subassemblies

46 and 48 can be transformed into a respective DC mation .could be printed out on paper or punched in cards for computer evaluation.

In a representative target system, stainless steel rods five feet long were utilized as the acoustic conductors l2 and 14 to which were attached piezoelectric sensors 1/4 inches diameter and H2 inches long. A binary counter such as the counter 72 operated from a standard crystal controlled clock 68 having a reference frequency of approximately 1 MHz measured the time difference for the arrival of acoustic shock fronts in the two rods. 20 shots from a 22 caliber magnum rifle were recorded at points across a 5 foot square paper target face. The automatic scoring system such as shown in FIG. I placed each round to within 0.050 inches of the actual bullet hole in the paper target. As noted above, this relatively small error can be further reduced by increasing the reference frequency of the clock 68 and matching the reference frequency to the velocity of sound in the rod (ratio of H5) as well as improving the mechanical alignment between the target and the metal rods.

A second embodiment of the subject invention is disclosed in FIG. 6 and differs from the embodiment disclosed in FIG. 1 by utilizing two elongated conductors 88 and 90 as the first acoustic energy conducting means and two

elongated conductors

92 and 94 as the second acoustic energy conducting means each having a

respective transducer

94, 96, 98 and mounted on one end thereof. The conductors 88 and 90 together with the

respective transducers

94 and 96 are utilized as a first pair for determining the distance L along the X axis while the

conductors

92 and 94 together with the

respective transducers

98 and 100 operates as a second pair to determine the distance H on the Y axis. It is to be noted that the first pair of

transducers

94 and 96 are located along the upper edge of the target 10 while the second pair of

transducers

98 and 100 are located along the right edge of the target 10.

In operation, the primary airborne shock wave N" expands outwardly from the hit 42 striking the sonic conductor rod 88 first causing a secondary acoustic wave to travel to and excite the transducer 94 at atime long before the primary wave front can reach it by traveling through air. The electrical signal produced thereby is coupled to the left" preamplifier 80. At a time later, the expanding primary acoustic shock wave strikes the conductor bar 90, activating the transducer 96, feeding a signal to the right" preamplifier 78, causing the X axis subassembly 48 to operate exactly as previously explained with respect to the circuitry shown in FIG. 1. The term V in the equation H (T T Vl2 now is the velocity of the shock wave in air. The travel times for the secondary shock wavesin the rods 88 and 90 have little significance since they are equal and orders of magnitude much less than the travel time in air. In a similar manner, the expanding shock wave radiating from the intersection 42 of the bullet with the target 10 causes a secondary shock wave to be set up first in time in the acoustic conductor rod 94, causing a signal to be produced by the acoustic transducer 100 which is fed to the up preamplifier 52 while a time later the primary wave strikes the lower sonic conductor rod 92 causing a signal to be produced by the transducer 98, which is then fed to the down" preamplifier 50. The signals produced first by the transducer 100 and then by the transducer 98 causes the Y axis subassembly 46 to generate an indication of the distance and direction of the hit 42 on the Y axis of the target 10.

In both embodiments of the subject invention shown in FIGS. 1 and 6 pairs of acoustic transducers are utilized for each X and Y coordinate axis in combination first with a single conductor and then with two conductors to indicate the position of the hit 42 by noting which of the transducers of each pair was activated first and determining the distance by noting the elapsed time between the activation of the other transducer of the pair.

An additional feature of the automatic target scoring system as disclosed by the subject invention is the possible rapid reset time and hence the rapid scoring which is attainable. Using for example a four foot square target, the acoustical disturbances from the shock wave will have passed the sonic acoustic conductors or rods in from five to ten milliseconds. The acoustic ringing of the conductors with proper damping such as shown and described with respect to P16. 2 will last approximately 5 milliseconds. Thus the acoustic transducers are capable of scoring shots or rounds spaced to milliseconds apart. By modifying the circuitry shown in FIGS. 1 and 6 to include an automatic reset and employing an additional data storage means such as an electronic digital shift register, 50 to 100 rounds per second can be scored. A safe estimate for rapid scoring capability is then in the order of 3,000 rounds per minute.

While the subject invention has been disclosed with a certain amount of detail, the method of employing the automatic target system will depend on individual requirements. For example, a system designed to score competition shootings certainly will differ in data handling and readout from one intended for basic rifle training employing silhouette targets. In a like manner, a target for aircraft with rapid fire capability and cookpit display will be unlike a system used for rifle testing and ammunition evaluation. A point to be made is that the basic target faces and scoring circuits disclosed herein, although applicable in many areas, must be modified to meet each user requirement.

Additionally, a completely automatic train fire course is envisioned. The trainee initiates the system at the starting point on the course and his actions such as speed of travel, reaction time, score, etc. are recorded as he progresses through the course to the exit. The sensors along the course activate for example, a pop up mechanism at the desired point of travel. The pop-up targets could be arranged along a jungle like path and consist of a mechanism to raise and lower the silhouette and two stationary sonic conductor rods, one vertical, one horizontal, wherein the vertical rod is camouflaged as a tree or post, while the horizontal rod is placed below the ground level. The sonic conductor rods moreover are calibrated to the silhouette for the target in the up position. One instructor could operate the course for a large number of trainees while still providing a degree of individual attention to each. The trainee would move down the path firing bursts of shots at the targets as they appear. On each target, reaction time, number of shots and hit/miss location of each shot are monitored in a control tower. If appropriate, a display panel of lights on a system relays the hit information back to the shooter before he moves to the next target. Using numbered lights, each round would be scored with a red, yellow, green code for miss, non-vital hits, and vital hits, respectively. The vital hit would also release the holding mechanism to drop the target if required.

Additionally rapid fire shots could be scored in real time and the X-Y information stored in a shift register. The maximum number of shots would be determined by the storage capacity provided. Shots missing the target area would be scored as misses left or right, fup or down. The stored information would be read out automatically and displayed to the operator. The method of recording and displaying the hit information depends on the training situation. Three of the most common display methods are the paper printer, the cathode ray tube (CRT), and the X-Y chart recorder. The X-Y coordinate data for each shot can be printed on tape for manual plotting or computer input in the future. The printer is the least expensive means for recording, but also the least informative for real time situations. The most rapid display is a storage cathode ray system where the X-Y information deflects the beam and the hit is recorded as a dot by intensity modulation of the beam. Unless a photograph is made of the scope face, no permanent record is available however. With the CRT a secondary printer is needed. An XY plotter is slower than the CRT, but provides the same graphic display and does produce a permanent record. The plotter can number the shots thus providing a complete history of the burst. The silhouette can be preprinted on graph paper and for economy a series of targets can be scored on a single sheet of the plotter paper. At the end of the course, the trainee would know immediately how well he performed and deficiencies discussed with the instructor. Patterns of the shot string may indicate improper use of the weapon, which could easily be corrected. Consistent misses in one direction would be indicated in the recorded data, since shots outside the target area are scored and the missed direction shown.

What has been shown and described, therefore, is a passive system which is simple in implementation and provides a linear X-Y readout not only of the location of the hit, but the distance from the center of the target without complex circuitry. Selective readout provides a great deal of flexibility in the manner in which the data can be displayed at a remotestation.

We claim as our invention:

1. An automatic gunnery target scoring system re-,

sponsive to the airborne primary acoustic shock wave of a supersonic projectile for detecting a projectile hit and the location thereof on a target, comprising, in combination:

first and second elongated acoustic energy translation means located adjacent the perimeter of said target in a substantially mutual perpendicular relationship along a first and second rectangular coordinate axis and being aligned substantially in a plane defined by said target to contact the outwardly expanding primary shock wave of said projectile wherein saidtranslation means transmits a relatively higher velocity secondary acoustic shock wave therein from the point of contact with said primary shock wave;

a pair of acoustic transducers mounted a selected dis tance apart on each of said first and second acoustic energy translation means in a predetermined relationship with said target, being respectively responsive to said higher velocity secondary wave to produce an electrical output signal upon the incidence thereof, said electrical output signals of each of said pair of transducers having a timed relationship which is a function of the difference in arrival times of said primary and secondary waves to the respective acoustic transducer;

first electrical circuit means coupled to one pair of acoustic transducers, being responsive to said electrical signals produced thereby to provide a first signal which is a measure of said difference of arrival times of said primary and secondary waves respectively to said one pair of sonic transducers;

second electrical circuit means coupled to the other pair of sonic transducers being responsive to said electrical signals produced thereby and providing a second electrical output signal which is a measure of said difference in arrival times of said primary and secondary waves along said second coordinate axis; and

indicator means coupled to said first and second electrical circuit means for providing an indication of said hit on said target along a first and second coordinate axes.

2. An automatic gunnery target scoring system responsive to the airborne acoustic shock wave of a su' personic projectile for locating the position of a hit" on a target, comprising:

a. first and second elongated acoustic energy translation means located adjacent the perimeter of said target in a substantially mutual perpendicular relationship along a first and second rectangular coordinate axis being aligned substantially in a plane defined by said target to contact the outwardly expanding airborne shock wave of said projectile wherein said translation means transmits a relatively higher velocity acoustic shock wave therein in response to contact with said airborne shock wave;

b. a pair of acoustic transducers coupled to each of said first and second translation means and responsive to said higher velocity shock wave to produce an electrical output signal upon the occurence thereof, said electrical output signals of each of said pair of transducers having a timed relationship which is a function of the position said projectile enters the target along one of said coordinate axes;

c. first electrical circuit means coupled to one pair of said transducers responsive to said electrical signals produced thereby for providing a first output signal which is a measure of the difference ofarrival time of said higher velocity shock waves respectively to each tranducer of said one pair of transducers;

d. second electrical circuit means coupled to the other pair of said transducers responsive to said electrical signals produced thereby for providing a second output signal which is a measure of the difference in arrival time of said higher velocity shock waves respectively to each transducer of said other pair of transducers; and

e. display means coupled to said first and second electrical circuit means for indicating the position said projectile enters said target.

3. An automatic gunnery target scoring system according to claim 2 wherein said first and second elongated acoustic energy translation means comprises re spectively a first and second acoustic conductor means and wherein each pair of acoustic transducers are mounted on the ends thereof.

4. An automatic gunnery target scoring system ac cording to claim 3 additionally including projectile bar rier means partially surrounding said acoustic conductor means being substantially coextensive therewith for preventing projectiles from striking said acoustic conductor means and having an unobstructed opening facing toward said target.

5. A target scoring system according to claim 4 additionally including acoustical isolation and damping material located between said acoustic conductive means and said projectile barrier means.

6. An automatic gunnery target scoring system according to claim 2 wherein said first and second elongated acoustic energy translation means respectively comprise first and second pairs of acoustic conductor means and wherein a pair of acoustic transducers are respectively mounted thereon such that each acoustic transducer is mounted on one end of a respective conductor means.

7. A target scoring system according to claim 6 wherein each acoustic transducer is mounted in the same end of a respective conductor means pair.

8. An automatic gunnery target scoring system according to claim 2 wherein said target has a predetermined length and a width dimension and said first and second elongated acoustic energy translation means comprises a first and second metallic rod member respectively having lengths substantially coextensive with said length and width dimension and being positioned substantially parallel thereto with the midpoints thereof substantially aligned with the center of said target.

9. An automatic gunnery target scoring system according to claim 2 wherein said first and second electrical circuit means each comprises:

a first and second level detector circuit respectively coupled to a pair of acoustic transducers and providing a control signal at the output thereof upon the occurrence of an electrical signal produced by the respective transducer coupled thereto;

a control circuit coupled to said first and second level detector circuit being responsive to the control signals produced thereby and generating a first output signal indicative of the control signal occurring first in time and a second output signal indicative of the difference in time between the occurrence of said control signals;

a reference frequency signal source;

a coincidence gate circuit coupled to said second output signal off control circuit and said reference frequency signal source for producing a pulse of said reference frequency signal having a pulsewidth proportional to the difference in arrival times of said primary and secondary acoustic wave to said pair of acoustic transducers; and

circuit means coupled between said coincidence gate and said indicator means for providing a control signal to said indicator means to generate a visual indication of the difference in said arrival times and thereby provide an indication of the location of said hit relative to the center of said target.

10. The invention as defined by claim 9 and additionally including signal amplifier means coupled between said pair of acoustic transducers and said first and second trigger circuits.

11. The invention as defined by claim 9 wherein said circuit means coupled between said coincidence gate.

trol circuit and said indicator means for resetting said control circuit after the occurrence of both control signals applied thereto.

13. The invention as defined by claim 9 wherein said reference frequency bears a predetermined relationship to the sound velocity in said acoustic energy translation means.

14. The invention as defined by claim 2 wherein said indicator means comprises a first and second numerical decimal indicator means for indicating the location of said hit along said first and second coordinate axis from the center of said target.

15. An automatic gunnery target scoring system responsive to the airborne primary acoustic shock wave of a supersonic projectile for detecting a projectile hit" and the location thereof on a target, comprising, in combination:

first and second elongated acoustic energy translation means located adjacent the perimeter of said target in a substantially mutual perpendicular relationship along a first and second rectangular coordinate axis and being aligned substantially in a plane defined by said target to contact the outwardly expanding primary shock wave of said projectile wherein said translation means transmits a relatively higher velocity secondary acoustic shock wave therein from the point of contact with said primary shock wave;

a pair of acoustic transducers mounted on each of said first and second acoustic energy translation means in a predetermined relationship with said target, being respectively responsive to said higher velocity secondary wave to produce an electrical output signal upon the incidence thereof, said electrical output signals of each of said pair of transducers having a timed relationship which is a function of the position said projectile enters said target and the difference in arrival times of said secondary waves to the respective acoustic transducer;

first electrical circuit means coupled to one pair of acoustic transducers being responsive to said electrical signals produced thereby for providing a first output signal which is a measure of said difference W of arrival times of said secondary waves respectively to said one pair of acoustic transducers along said first coordinate axis;

second electrical circuit means coupled to the other pair of acoustic transducers being responsive to said electrical signals produced thereby for providing a second output signal which is a measure of said difference in arrival times of said secondary waves to said other pair of acoustic transducers along said second coordinate axis; and

indicator means coupled to said first and second electrical circuit means for providing an indication of said hit on said target along said first and second coordinate axes.

Claims

1. An automatic gunnery target scoring system responsive to the airborne primary acoustic shock wave of a supersonic projectile for detecting a projectile ''''hit'''' and the location thereof on a target, comprising, in combination: first and second elongated acoustic energy translation means located adjacent the perimeter of said target in a substantially mutual perpendicular relationship along a first and second rectangular coordinate axis and being aligned substantially in a plane defined by said target to contact the outwardly expanding primary shock wave of said projectile wherein said translation means transmits a relatively higher velocity secondary acoustic shock wave therein from the point of contact with said primary shock wave; a pair of acoustic transducers mounted a selected distance apart on each of said first and second acoustic energy translation means in a predetermined relationship with said target, being respectively responsive to said higher velocity secondary wave to produce an electrical output signal upon the incidence thereof, said electrical output signals of each of said pair of transducers having a timed relationship which is a function of the difference in arrival times of said primary and secondary waves to the respective acoustic transducer; first electrical circuit means coupled to one pair of acoustic transducers, being responsive to said electrical signals produced thereby to provide a first signal which is a measure of said difference of arrival times of said primary and secondary waves respectively to said one pair of sonic transducers; second electrical circuit means coupled to the other pair of sonic transducers being responsive to said electrical signals produced thereby and providing a second electrical output signal which is a measure of said difference in arrival times of said primary and secondary waves along said second coordinate axis; and indicator means coupled to said first and second electrical circuit means for providing an indication of said ''''hit'''' on said target along a first and second coordinate axes.

2. An automatic gunnery target scoring system responsive to the airborne acoustic shock wave of a supersonic projectile for locating the position of a ''''hit'''' on a target, comprising: a. first and second elongated acoustic energy translation means located adjacent the perimeter of said target in a substantially mutual perpendicular relationship along a first and second rectangular coordinate axis being aligned substantially in a plane defined by said target to contact the outwardly expanding airborne shock wave of said projectile wherein said translation means transmits a relatively higher velocity acoustic shock wave therein in response to contact with said airborne shock wave; b. a pair of acoustic transducers coupled to each of said first and second translation means and responsive to said higher velocity shock wave to produce an electrical output signal upon the occurence thereof, said electrical output signals of each of said pair of transducers having a timed relationship which is a function of the position said projectile enters the target along one of said coordinate axes; c. first electrical circuit means coupled to one pair of said transducers responsive to said electrical signals produced thereby for providing a first output signal which is a measure of the difference of arrival time of said higher velocity shock waves respectively to each tranducer of said one pair of transducers; d. second electrical circuit means coupled to the other pair of said transducers responsive to said electrical signals produced thereby for providing a second output signal which is a measure of the difference in arrival time of said higher velocity shock waves respectively to each transducer of said other pair of transducers; and e. display means coupled to said first and second electrical circuit means for indicating the position said projectile enters said target.

3. An automatic gunnery target scoring system according to claim 2 wherein said first and second elongated acoustic energy translation means comprises respectively a first and second acoustic conductor means and wherein each pair of acoustic transducers are mounted on the ends thereof.

4. An automatic gunnery target scoring system according to claim 3 additionally including projectile barrier means partially surrounding said acoustic conductor means being substantially coextensive therewith for preventing projectiles from striking said acoustic conductor means and having an unobstructed opening facing toward said target.

9. An automatic gunnery target scoring system according to claim 2 wherein said first and second electrical circuit means each comprises: a first and second level detector circuit respectively coupled to a pair of acoustic transducers and providing a control signal at the output thereof upon the occurrence of an electrical signal produced by the respective transducer coupled thereto; a control circuit coupled to said first and second level detector circuit being responsive to the control signals produced thereby and generating a first output signal indicative of the control signal occurring first in time and a second output signal indicative of the difference in time between the occurrence of said control signals; a reference frequency signal source; a coincidence gate circuit coupled to said second output signal off control circuit and said reference frequency signal source for producing a pulse of said reference frequency signal having a pulsewidth proportional to the difference in arrival times of said primary and secondary acoustic wave to said pair of acoustic transducers; and circuit means coupled between said coincidence gate and said indicator means for providing a control signal to said indicator means to generate a visual indication of the difference in said arrival times and thereby provide an indication of the location of said hit relative to the center of said target.

11. The invention as defined by claim 9 wherein said circuit means coupled between said coincidence gate and said indicator means comprises a counter circuit.

12. The invention as defined by claim 9 and additionally including manual reset means coupled to said control circuit and said inDicator means for resetting said control circuit after the occurrence of both control signals applied thereto.

15. An automatic gunnery target scoring system responsive to the airborne primary acoustic shock wave of a supersonic projectile for detecting a projectile ''''hit'''' and the location thereof on a target, comprising, in combination: first and second elongated acoustic energy translation means located adjacent the perimeter of said target in a substantially mutual perpendicular relationship along a first and second rectangular coordinate axis and being aligned substantially in a plane defined by said target to contact the outwardly expanding primary shock wave of said projectile wherein said translation means transmits a relatively higher velocity secondary acoustic shock wave therein from the point of contact with said primary shock wave; a pair of acoustic transducers mounted on each of said first and second acoustic energy translation means in a predetermined relationship with said target, being respectively responsive to said higher velocity secondary wave to produce an electrical output signal upon the incidence thereof, said electrical output signals of each of said pair of transducers having a timed relationship which is a function of the position said projectile enters said target and the difference in arrival times of said secondary waves to the respective acoustic transducer; first electrical circuit means coupled to one pair of acoustic transducers being responsive to said electrical signals produced thereby for providing a first output signal which is a measure of said difference of arrival times of said secondary waves respectively to said one pair of acoustic transducers along said first coordinate axis; second electrical circuit means coupled to the other pair of acoustic transducers being responsive to said electrical signals produced thereby for providing a second output signal which is a measure of said difference in arrival times of said secondary waves to said other pair of acoustic transducers along said second coordinate axis; and indicator means coupled to said first and second electrical circuit means for providing an indication of said ''''hit'''' on said target along said first and second coordinate axes.