Range Scoring System

Abstract

There is disclosed a preferred embodiment of a semi-automatic range scoring system which utilizes a closed-circuit television system in combination with a light pen unit and computer. The observer uses the light pen to mark the point of weapon impact on a T.V. monitor screen for each of the camera displays. Each marking causes the light pen unit to transfer digital positional information of the point of impact to the computer. Once the impact has been marked twice, the computer immediately processes the positional data to determine miss-distance and display same. The system is also adaptable for scoring miss-distance with regard to a moving target. In both cases, miss-distance information is obtained on an almost simultaneous basis with the impact of the weapon.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a range scoring system for scoring accuracy of air-to-ground weapons and, more particularly, to an improved range scoring system utilizing a precision video subsystem and automatic computation of miss distance.

Various range scoring systems are knowm for scoring the accuracy of air-to-ground weapons, such as bombs, rockets, missiles, and the like. The present manual system typically employs a pair of optical sighting means at fixed spaced locations on the range by which two different angles of weapon impact are determined. The coordinates of impact are then derived by triangulation or the use of routine trigonometric equations. Another type of system uses a pair of spaced television cameras whose baselines form a right angle. The weapon impact is recorded by both cameras on video tape. The tape is then played back and the point of impact seen by each camera is measured on a grid. The measurement data are then fed into a computer to determine miss distances.

The problem with the prior art techniques is that they are primarily manual in nature and thus susceptible to human error in the making of measurements or the sighting of angles, which naturally leads to errors in the resulting miss distance solution. Furthermore, the computations of miss distances and the like are obtained generally well after time of impact instead of simultaneously therewith. This delay is particularly disadvantageous where subsequent weapon firings or launchings must be retarded until the results of the prior firing have been received. Other forms of prior-art systems are generally limited in range or cannot readily score different types of targets, or are susceptible to weapon damage.

The need, therefore, exists for a range scoring system in which the possibility of human error is held to a minimum and which provides impact coordinates or miss distances on essentially a real-time basis.

SUMMARY

The present invention overcomes the problems of prior-art range scoring systems by providing an improved system which is semi-automatic and in which the likelihood of human error is reduced by eliminating manual distance and angle measurements relative to weapon impact and by providing impact positional information on an almost simultaneous basis, such as coordinates of the impact point, or the distance and angle by which the point of weapon impact missed the range center or other reference point.

In accordance with the purposes of the invention, as embodied and broadly described herein, the scoring system for a target range includes means for viewing said range and the impact of weapons when such occur, means for displaying the output of said viewing means, a light pen unit responsive to the receipt of said viewing means output and the display of said displaying means for generating signals respresentative of impact location, and means for receiving said signals generated by said light pen unit and calculating impact position.

The invention consists in the novel circuits, systems, parts, constructions, arrangements, combinations, and improvements shown and described. The unique features and advantages of the invention will become apparent by reading the following description which, taken in conjunction with the accompanying drawings which are incorporated in and constitute a part of the specification, disclose preferred embodiments thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a target range and certain of the apparatus employed in the present invention;

FIG. 2 is a block diagram of the improved scoring system forming the present invention;

FIG. 3 is a block diagram of pertinent portions of the light pen unit shown in FIG. 2;

FIGS. 4-7 are plan views of target ranges used in explaining operation of the present invention;

FIGS. 8A and 8B together present a block diagram of the computer shown in FIG. 2; and

FIG. 9 is a preferred embodiment of the control logic of FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings.

Referring now to the drawings, FIG. 1 presents a perspective view of a typical target range 10, together with certain of the apparatus employed in the present invention. The range is shown here as having a target circle 12 of a known radius and whose center forms the target center 14. As an example, the radius of the target circle can be 2,000 feet.

In accordance with the present invention, there are means provided for viewing said range and the impact of weapons when they occur. As embodied herein, a pair of television cameras 16 and 18 are positioned on the range 10 to view the target area within circle 12. Cameras 16 and 18 are aimed at the target center 14, and the imaginary lines running from the target center to each camera 16 and 18 are called the camera baselines 20 and 22, respectively. Preferably, the camera baselines are positioned an equal distance back from the target center along their respective baselines. An example of this distance is 6,000 feet.

The cameras are preferably positioned so that their baselines 20 and 22 coincide with the range coordinates or at 45.degree. to these coordinates. As shown in FIG. 1, the cameras 16 and 18 have been positioned at 45.degree. to the range coordinates. In all, eight possible camera locations can be selected in which the camera baselines coincide with or are 45.degree. to the range coordinates, which provides substantial system flexibility. Assuming for ease of discussion that range 10 is a bombing range, then the X-coordinate 24 can be the aircraft approach or run-in line, and the Y-coordinate 26 is thus perpendicular to this run-in line. The camera baselines thus coincide with the run-in line coordinates, or are at 45.degree. thereto. It should be understood, however, that other baseline/run-in line angles can also be accommodated, In fact, angles of camera baseline to run-in line between 0.degree. and 90.degree. can be selected, but such angles must then be compensated for in computing miss distances, as later described.

In accordance with the invention, there are means for displaying the output of said viewing means. As embodied herein, the outputs of the cameras 16 and 18 are applied to the input of a remote video monitor 28. Each output comprises a composite picture signal including synchronizing pulses which is transmitted to the monitor 28. The monitor 28 is enlarged at the left of FIG. 1 to illustrate an observer 34 viewing the display screen 36 of the monitor 28 and using a manual probe 38 to manually "mark" the point of weapon impact by noting the origin of the impact cloud, the effect of this being hereinafter explained. The particular communication link between the cameras and the monitor which is preferred is a low-loss coaxial cable, shown as cables 30 and 32 in the drawing, although other conventional links, such as an RF link, can obviously be used.

The cameras 16,18 cables 30,32, and monitor 28 in effect define a closed-circuit television system. In preparing the system for operation, each camera is preferably boresighted to an alignment target (not shown) temporarily placed at the target center 14. Boresighting is accomplished by moving a camera until the target center is in the electronic center of the video picture of the monitor 28. Each camera lens is preferably chosen such that the field-of-view of target 12 fills approximately 85 percent to 95 percent of the monitor screen. Ideally, one camera is tilted slightly upward and the other camera is tiled slightly downward. As a result, the range as seen by one camera fills the bottom half of the monitor screen, and the range as seen by the other camera fills the top half of the screen. This serves as an aid to the observer in marking targets. Alignment targets (not shown) can be placed on the edge of the target, tangent to the edge of the camera field-of-view, to provide reference points to calibrate or check the calibration of a computer used to automatically calculate weapon impact position. After boresighting, the cameras are preferably locked in the boresighted position on the camera mounts.

In the selection of system components, precision apparatus is preferred. For example, cameras which have good linearity minimize system inaccuracy. Similarly, the monitor 28 should have good linearity and visual acuity so that accurate measurement can be derived from the markings of the probe 38. Monitor 28 is conventional in construction and includes a cathode ray tube (not shown) positioned such that its electron beam is directed against the inside of screen 36 during the scanning of a frame.

In the operation of the present system, to the extent to which it has been described, assume an airplane 40 flies over the target circle 12 along run-in line 24 and drops a bomb which impacts and explodes at point 42. The picture from camera 16 is simultaneously displayed on screen 36 and the observer immediately "marks" the impact point by contacting the point of his probe 38 to the impact point displayed on the screen. The picture from camera 18 is now switched into monitor 28, replacing the picture from camera 16 on screen 36. The observer 34 now marks the impact point, as viewed by camera 18, with probe 38. The data from these two markings are immediately presented to the computer, as later described, and miss distance or the like is immediately calculated and displayed.

In FIG. 2, there is shown a block diagram of the present invention including the electronic apparatus additional to the cameras 16 and 18 and the monitor 28 previously described. As embodied herein, the output of camera 16 and the output of camera 18 are both applied to the input of video switch 44. The purpose of video switch 44 is to select individually the composite video signal of the target area being transmitted by either camera 16 or camera 18 and apply it to monitor 28 for display. Video switch 44 is conventional in construction and can be a high-performance reed switch assembly which switches the center conductor of the video cable. If desired, a special-effect picture splitter can be used in place of the video switch which would split the video presentation on monitor 28 between the output of camera 16 and the output of camera 18.

The output of video switch 44 is connected to the video equalization amplifier 46. Amplifier 46 is also of a conventional construction, and its primary function is to compensate for high-frequency losses caused by video cable 30 or 32 so that the composite video signal applied to monitor 28 is returned to its original quality.

In accordance with the invention, a light pen unit is provided which is responsive to the receipt of the viewing means output and the display of the displaying means to generate signals representative to impact location. As embodied herein, a light pen unit 50 is connected between the output of amplifier 46 and the input of monitor 28. The light pen unit includes manual probe 38 capable of being disposed adjacent to the outside of screen 36 to sense or detect the passage of the electron during scanning. Preferably, the probe 38 is connected to a photosensitive detector which is used in a manner described hereinafter.

In accordance with the invention, means are provided for receiving the signals generated by the light pen unit 50 and calculating impact position. As embodied herein, the receiving and calculating means 52 automatically processes the digital signals applied from light pen unit 50 so that impact position can be calculated and displayed. Preferably, such means 52 is a digital computer which performs the basic geometric calculations necessary to determine impact position and displays this answer in the desired coordinates, as described in detail hereinafter.

In accordance with the invention, there are also provided means for actuating the video switch 44 so that the composite picture signal from the pair of cameras 16 and 18 is sequentially applied to monitor 28. As embodied herein, computer 52 is connected to video switch 44 by line 54 so that the switching between cameras 16 and 18 is automatically obtained once the positional information of the impact as viewed by the first camera has been fed to computer 52. This automatic switching reduces the amount of time it takes an operator to manipulate probe 38 to mark the impact point as viewed by both cameras 16 and 18. Thus, the marking of the monitor as viewed by the second camera, e.g., camera 18, can be performed more quickly than where switch 44 must be manually actuated. If desired, however, manual actuation of switch 44 can be used an alternative to automatic switching under control of computer 52.

The light pen unit 50 is used to generate signals proportional to the X-Y coordinates of any point on the screen 36 of monitor 28. The coordinates are fixed by placement of probe 38 and are simultaneously applied in digital form to computer 52. Preferably, the light pen unit is of a conventional construction, and as an example can be the Model 4551 light pen unit manufactured by Tektronix, Inc., of Beaverton, Oregon, the construction and operation of which is disclosed in the instruction manual for this unit published by Tektronix, Inc. in 1971. A generalized block diagram of the construction of this light pen unit as it pertains to the present invention is disclosed in FIG. 3.

The video input is applied to a sync separator 60 whose output is applied to the input of four circuits to initiate the generation of signals therefrom. The first horizontal sync pulse in the frame to be scanned is applied to a vertical ramp 62 which outputs an analog ramp voltage which progressively increases during the time it takes for the frame to be scanned. This output is applied to one input of a comparator circuit 64. Vertical counter 66 counts the horizontal sync pulses during the frame and its digital output is continually applied to the input of latch 68. When latch 68 is clocked, the count that is at its input is transferred to its output and retained. The output of latch 68 is connected into a digital-to-analog converter 70 whose output, in turn, is connected to the second input of comparator 64.

The horizontal ramp circuit 72 provides an analog output voltage which progressively increases during the duration of the scan of one horizontal line in the frame. Ramp 72 is initiated by each horizontal sync pulse in the frame. Its output is applied to one input of comparator 74. Horizontal counter 76 preferably includes an oscillator (not shown) an, in effect, constitutes a digital timing circuit which is actuated by each horizontal synchronizing pulse applied by sync separator 60. Thus, horizontal counter 76 undergoes a counting cycle and accumulates a digital count for each horizontal synchronizing pulse during the frame. The output of counter 76 is applied to a latch circuit 78 which has the same construction and function as latch circuit 68. The digital output of latch 78 is connected to a digital-to-analog converter 80 whose output is in turn connected to the second input of comparator 74. The pair of counters 66 and 76 together are responsive to the output of sync separator 60 and thereby the output of the cameras 16 and 18 for accumulating counts proportional to the monitor's electron beam position during scanning.

The output of comparators 64 and 72 are connected to the input of a cursor assembly 82 which develop the signals to form the cross-shaped cursor which the light pen unit applies to the screen 36 of the monitor. The output of cursor assembly 82 is connected into the cursor mixer 84 where it is mixed with the input composite video signal. The composite video signal including the cursor signals is applied to video amplifier 86 and the output of this amplifier is sent out of light pen unit 50 to the monitor 28.

Manual probe 38, as embodied in FIG. 3, is a light pen sized to be held in a person's hand so as to be disposed adjacent to the screen of a television monitor, as mentioned previously. A fiber optics bundle is mounted inside of light pen 38 so that the front end 90 of the bundle is disposed adjacent the tip of the light pen.

As embodied herein, the light pen unit 50 further includes a photosensitive detector which is connected to the probe 38 to convert the light received by the passage of the electron beam into an electrical signal. Preferably, this detector is a photomultiplier 92 which is connected to the opposite end of the fiber optics bundle 88. The photomultiplier 92 is shown separate from the light pen 38 but, if desired, can be enclosed within the body of the light pen. The output of photomultiplier 92 is connected to amplifier 94, whose output in turn is connected to the clock input of latches 68 and 78.

In accordance with the invention, light pen unit 50 further includes means responsive to the output of the probe for transferring the accumulated counts of said counters to said receiving and calculating means. As embodied herein, a manually operable switch 96 is formed on said probe and is connected by a wire 98 to the lock or hold input of registers 100 and 102. The signal inputs to registers 100 and 102 are received from the outputs of latch circuits 68 and 78, respectively. The digital outputs from each of registers 100 and 102 are applied over lines 104 and 106, respectively, which are connected into the input circuitry of computer 52. Preferably, line 104 comprises nine wires in parallel for the application of the horizontal digital count to the computer registers. Line 98 is also connected from the light pen unit to the computer.

The operation of the light pen unit has to a major extent been described in the preceding description. However, a brief review of the operation now follows. The observer picks up the light pen 38 and places the tip of this pen lightly against the face plate covering the screen 36 of the television monitor 28. Each time the scanning beam passes under the tip of pen 38 during the scan of a frame, a pulse of light is coupled through the fiber optics 88 to the photomultiplier 92, and an electrical pulse is sent out of photomultiplier 92, amplified, and applied as the clock signal to latch circuits 68 and 78.

At the same time, the sync separator circuit 60 is extracting the horizontal sync pulses from the input composite video signals and applying them to counters 66 and 76. The vertical counter 66 counts the total number of horizontal sync pulses in each frame. e.g., 525 pulses. It is then reset and begins a new count in response to the vertical sync pulse. The horizontal counter 76 is initiated by each sync pulse. It is reset between each scan line. Assuming 525 horizontal scan lines per frame, the horizontal counter 76 goes through 525 counting cycles for each frame of the video signal. Thus, at any time the counts accumulated in counters 66 and 76 are proportional to the vertical and horizontal positions of the electron beam during its frame scan.

When the photomultiplier 92 sends a clock signal to latches 68 and 78 in response to the passage of the electron beam past the tip of light pen 38, the digital counts which have been reached at that instant in counters 66 and 76 are passed from the input to the output of latches 68 and 78, respectively. These signals are converted and applied to comparators 64 and 74 where they are compared with the analog signals developed respectively by ramps 62 and 72. As the level of each ramp attains the level of its associated converter, the comparator 64 applies a signal to cursor assembler 82. The cursor signals are then mixed with the composite video signals and the resultant signal is amplified and applied to the monitor. A cursor in the shape of a cross or any other convenient shape now appears on screen 36 under the tip of lighpen 38. Ideally, this cursor is displaced slightly to avoid errors that might be caused by visual interference by the probe or the operator's hand covering the point of weapon impact.

The frame frequency is sufficiently rapid, e.g., 30 frames per second, so that the cursor fills in rapidly on the monitor screen 36. Because the cursor is now referenced to the position of the light pen 38 by detection of the electron scanning beam, the cursor can be moved over the face of the screen in direct response to pen movement.

When an airplane passes over the range to drop a bomb, the observor 34 (FIG. 1) first merely touches his light pen 38 lightly to the screen 36 to generate a cursor as described above. He now moves the cursor by movement of pen 38 across the face of the screen until the cursor is positioned at the point of weapon impact as viewed by the observer on the monitor screen. The observer now closes switch 96 of light pen 38 which causes the registers 100 and 102 to hold the counts then being applied by latches 68 and 78, respectively. The digital horizontal and vertical position signals of the cursor position, and thereby the point of weapon impact, are applied by lines 104 and 106 to computer 52. A signal is also applied by line 98 to instruct the computer to accept these digital signals. Once these positional signals have been stored in computer 52, video switch 44 switches the output of the other camera 18 into monitor 28 and the observer 34 marks this new point of weapon impact in the same manner as aforedescribed. The digital horizontal and vertical counts indicative of this new impact position are also transferred to computer 52.

Switch 96 can be positioned on light pen 38 to be actuated by the finger, thumb, or other movement of the hand. Preferably, switch 96 is incorporated into the point of pen 38 so that it is closed by depression of the point firmly against the screen 36. This simplifies the marking procedure because the light pen is already in contact with the screen and it merely requires the application of additional hand pressure inwardly against the screen to cause the tip to be depressed. Line 98, in actuality, can be composed of two wires with the switch completing the circuit, or, alternatively, a source of potential could be contained in pen 38. The fiber optics 88 and the line 98 are preferably contained within the same sheath or cable for compactness and also to lessen the likelihood of damage to these members.

The computer 52 accepts the data from the light pen unit 50 and calculates the coordinates of weapon impact. It then displays the answer in a format selected by the computer operator, preferably either in a distance/clock code format or a right/left-over/under format. With reference to FIG. 4, a Cartesian coordinate system of the range 10 is shown with the cameras' baselines 20, 22 coincident with the range coordinates 24, 26. The aircraft run-in line is here selected as Y-axis 26. A "hit" or point of weapon impact 42 is also arbitrarily positioned on the range. The symbols shown are defined as follows:

.theta. = Hit angle -- angle from center of camera field-of-view to hit location 42.

D = Distance from camera to center of target.

x = Hit distance measured from the hit impact 42 to camera 18 optical baseline 22 and parallel to camera 16 optical baseline 20.

y = Hit distance measured from the hit impact 42 to camra 16 optical baseline 20 and parallel to camera 18 optical baseline 22.

The impact coordinates of hit 42 are therefore:

x = (D.sub.1 + y) tan .theta..sub.1 1

y = (D.sub.2 - x) tan .theta..sub.2 2

By substitution, these equations become:

x = (D.sub.1 tan .theta..sub.1 + D.sub.2 tan .theta..sub.1 tan .theta..sub.2)/(1 + tan .theta..sub.1 tan .theta..sub.2) 3

y = (D.sub.2 tan .theta..sub.2 - D.sub.1 tan .theta..sub.1 tan .theta..sub.2)/(1 + tan .theta..sub.1 tan .theta..sub.2) 4

Computer 52 solves equations 3 and 4.

When the aircraft run-in line is not coincident with one of the range axes, the coordinates must be rotated through the angle the run-in line makes with such range axis so that the hit coordinates can be referenced to the run-in line. FIG. 5 shows a Cartesian coordinate system of the range 10 with the aircraft run-in line non-concident with a range axis. The symbols shown are defined as follows:

.phi. = Coordinate rotation angle.

x' = Hit distance measured from the hit impact 42 to the run-in line (y' axis) and perpendicular to the run-in line.

y' = Hit distance measured from the hit impact 42 to the x' axis, which is perpendicular to the run-in line, parallel to the run-in line.

The impact coordinates of hit 42 are therefore:

x' = x cos .phi. + y sin .phi. 5

y' = ycos .phi. - x sin .phi. 6

The values of x and y are found by first solving equations (3) and (4). Computer 52 also solves equations 5 and 6.

The values of x and y, i.e., miss distance, displayed by computer 52 is in a right/left-over/under format for the examples just described. If a distance/clock code format is desired, additional computations are necessary. With reference to FIG. 6, the additional symbols shown are defined as follows:

R = Distance from target center to hit location 42.

C = Clock code as in a conventional time clock (0:00 to 12:00 o'clock).

K = Conversion constant to convert 360.degree. or 2 .pi. radians to 12:00 o'clock.

X = x axis of coordinate selected to go through distance/clock code generator, e.g., x or x'.

Y = y axis of coordinate selected to go through distance/clock code generator, e.g., y or y'.

The distance R is therefore:

R = .sqroot.x.sup.2 + y.sup.2 7

and the clock code equations are:

If X is (+) and Y is (+), the range of C is 0:00 to 3:00 o'clock, and C = K arc sin .vertline.X.vertline./R; 8

if X is (+) and Y is (-), the range of C is 3:00 to 6:00 o'clock, and C = K arc sin .vertline.Y.vertline./R + 3; 9

if X is (-) and Y is (-), the range of C is 6:00 to 9:00 o'clock, and C = K arc sin .vertline.X.vertline./R + 6; 10

if X is (-) and Y is (+), the range of C is 9:00 to 12:00 o'clock, and C = K arc sin .vertline.Y.vertline./R + 9. 11

the computer also solves equations 7 through 11.

The scoring system of the present invention can also be used to socre moving targets in addition to a stationary target. The moving target becomes the center of the scoring system. With reference again to FIGS. 1 and 2, assume that a moving target, such as a radio-controlled tank (not shown), is moving over target range 10, and that an aircraft flies over the range and drops a bomb aimed at the tank. The bomb impacts and explodes on the ground (assuming a miss) at a point 42.

The observer 34 first "marks" the tank position with light pen 38 for both cameras 16 and 18 in the same manner as has been previously described for marking an impact point. Digital information proportional to instantaneous target position is applied by light pen unit 50 to computer 52. This data establishes the center the scoring system with which to reference weapon impact position 42. The observer next marks the impact position with the light pen 38 for both cameras and this digital information is also applied by light pen unit 50 to computer 52. The computer now calculates and displays the coordinates of weapon impact with reference to the moving target at the time of impact.

With reference to FIG. 7, a Cartesian coordinate system of the range 10 is shown with the moving target location and hit 42 arbitrarily positioned on the range. The symbols shown are defined as follows:

x'.sub.1 = Moving target location along x' axis.

y'.sub.1 = Moving target location along y' axis.

x'.sub.2 = Hit location along x' axis.

y'.sub.2 = Hit location along y' axis.

.DELTA. x' = Distance from moving target to hit location measured parallel to x' axis referenced from moving target location.

.DELTA. y' = Distance from moving target to hit measured parallel to y' axis referenced from moving target location.

The impact coordinates of hit 42 with reference to the moving target are therefore:

.DELTA. x' = x'.sub.2 - x'.sub.1 12

.DELTA. y' = y'.sub.1 - y'.sub.2 13

Computer 52 solves equations 12 and 13. The x and y positions of both the target and hit are first determined with respect to the camera axes, following the example of FIG. 4, and then rotated through the angle .phi. so that they are referenced to the range axes, following the example of FIG. 5.

A block diagram of computer 52 showing a mechanization which encompasses small, large, and movable vehicle targets is shown in FIGS. 8A and 8B. Computer 52 is divided into two sections 52a and 52b. Section 52b is used when the target is a moving target, otherwise only sections 52a is used. As embodied herein, each of computer sections 52a and 52b includes a pair of registers, each of said registers being connected to the output of the light pen unit 50 to store the count proportional to electron beam horizontal position, namely, that derived from counter 76 (FIG. 3). Preferably, section 52a includes a pair of input storage registers 110 and 112. One of these registers, e.g., register 110, receives the digital output of counter 76 in response to the output of the marking of weapon impact, as viewed by camera 16. The other register 112 receives the digital output of counter 76 in response to the output of the marking of weapoin impact, as viewed by the other camera 18. When a moving target is used, registers 110 and 112 are loaded in the same manner with digital signals proportional to position of the moving target at the time of weapon impact while registers 114 ad 116 receive weapon impact positional data. Once the input data is received by these registers, it is held for processing.

The remainder of computer section 52a, except for the display apparatus, as embodied herein functions as the means for electronically processing the stored counts to calculate impact position. The remainder of computer section 52b functions as means for electronically processing the stored counts to calculate instantaneous position of the moving target. Included in these processing means are means for initiating processing of the contents of the register after counts have been stored in each of the registers 110, 112, 114, and 116 which are being used. Preferably, this means includes a conventional control logic circuit 118 which controls the data being entered in the registers and initiates processing after all inputs have been entered and stored. For example, the input signal applied on line 98 by each actuation of light pen 38 causes control logic 118 to condition sequentially each of the registers 110, 112, 114. and 116 via the data hold line so that each register selectively accepts in turn the digital output of counter 76 via input lines 104. Control logic 118 is also connected to video switch 44 (FIG. 2) via line 54 so that video switch 44 is automatically switched from one camera to the other following application of the count associated with the first camera into one of the input registers of computer 52. When all of the input registers have been properly loaded with selected data, calculate signal is sent to the computation portion of the computer. A signal is also sent to the display logic which enables it to display the calculated answer.

The vertical count applied on line 106 to control logic 118 is preferably not used in the computations. The control logic receives only the most significant bit of this digital count and determines if the observer is marking the correct part of the screen. For example, if a camera output is being displayed on the upper part of the monitor screen, and the observer inadvertently marks the lower part of the screen, then the most significant bit will be a One instead of a Zero and the control logic will reject the digital data. Thus, the vertical count can be used to insure that the correct camera or correct part of the screen is being scored.

The computations of the computer basically follow the following order, assuming a moving target is included in the scoring system:

1. Convert input data to angles .theta..sub.1, .theta..sub.2, .theta..sub.3, .theta..sub.4 referenced to the center of the target area.

2. Calculate Calibrated .theta..sub.1, .theta..sub.2, .theta..sub.3, and .theta..sub.4.

3. Calculate Tan .theta..sub.1, Tan .theta..sub.2, Tan .theta..sub.3, and Tan .theta..sub.4.

4. Calculate right/left-over/under in camera coordinates.

5. Rotate coordinates if necessary to aircraft run-in coordinates.

6. Perform moving target miss distance calculations.

7. Calculate distance/clock code.

8. Display answer for stationary target, or moving target in over/under-right/left or distance/clock code.

The function performed in each computation block of the computer block diagram of FIGS. 8A and 8B is now briefly described. The digital count stored in each register is proportional to .theta.. The Sign Magnitude Conversion 120 is necessary to convert the stored .theta. to an angle .theta. referenced to the center of the target area. This also simplifies the computer calculations. The Sign Change Logic 122 is provided in order to change the sign of the input angle if the camera locations on the range are changed. The magnitude of the input angle .theta. is calibrated for slight camera-to-camera variations in the field of view. This is accomplished by multiplying in Multiplier 124 the input angle by a constant which can be varied to achieve calibration. The input angle is also multiplied by the target size scale factor whose value is determined by the particular camera lens used. Because tangent .theta. is the major variable in the coordinate calculations, it is calculated at 126 before entering the coordinate calculation portion of the computer.

Continuing with the functions of the computer block diagram, the Coordinate Calculator 128 accepts the tan .theta. calculations, and the camera position distance components, and calculates the projectile hit in X and Y camera coordinates. This information is then sent to the Axis Rotator 130 which rotates the axis of the input camera coordinate data to that of the aircraft run-in line or any other desired orientation. A calculate command input to the axis rotator commands the Axis Rotator to rotate the axis. If there is no calculate command, the input data will proceed through the Axis Rotator 130 without being converted. The outputs of the Axis Rotator go to both the Variable Target Center Calculation 132 and the Distance/Clock Code Generator 134.

The variable target center calculations are performed in block 132 for moving target applications. The instantaneous position of the moving target is designated as the target center. Any other point within the overall target area could also be designed as the target center if desired. This computation basically moves the center of the coordinate system to the specified location selected by the observer using the light per unit. To perform computation, inputs are received which specify the center coordinates of the new coordinate system (location of moving target), and the coordinate of the projectile hit. The computed output is sent to the Distance/Clock Code Generator 134.

The Distance/Clock Code Generator 134 operates on the X, Y coordinates (over/under-right/left) to convert them to a modified polar coordinate system (distance/clock code). Coordinate data from fixed target and moving target are both applied to this generator. However, only one set of inputs is accepted depending on the input select command signal which the operator uses to select fixed target or moving target operation. There is also a calculate input which commands the Distance/Clock Code generator 134 to generate its normal distance/clock code output. If there is no calculate command, input data will proceed through this block without being converted and will go to the Display Logic 136 in the over/underright/left format.

The Display Logic 136 converts the binary sign magnitude answer into a binary-coded-decimal output. Display Logic 136 also contains conventional logic drives for driving Displays 138 and controlling display power. An input from the control logic 118 establishes when the anxwer will be displayed. Set functions in the computer are manually set prior to computer operation.

Computer 52 as has been described is seen to be a special purpose computer designed to perform miss-distance calculations. However, if desired, a properly-programmed general purpose digital computer can obviously be used. A mini-computer of the type which is in popular use today can also be used if supplemented by the addition of input registers 110, 112, 114, and 116, control logic 118, and the Sign Magnitude Conversion function.

FIG. 9 shows the preferred embodiment of a control logic unit 118 in combination with the computer registers and the horizontal output register 100 of the light pen unit 50. The control logic 118 sequentially activates each register 110, 112, 114, and 116 to receive the digital information being applied on lines 104 in response to light pen marking. The signal applied from the light pen 38 on line 98 when switch 96 (not shown) is closed is applied through inverter 140 to NAND gates 142 and 144. The output of NAND gate 142 is connected to flip-flop 146, and the output of NAND gate 144 is connected into flip-flop 148. The line 106 is preferably a single line which carries the most significant bit out of vertical register 102 in the light pen unit, and this line is applied to NAND gate 142 and through inverter 150 to NAND gate 144.

Assuming that camera 16 (FIG. 2) is first selected by switch 44 and is being displayed on the upper half of monitor screen 36, the output from light pen 38 in response to the marking of a target impact on the screen is applied to gates 142 and 144. However, the most significant bit on line 106 is at this time a Zero and only gate 144 is enabled. The output of gate 144 goes from a One to a Zero. Flip-flop 148 is Set, and a signal is applied out of this flip-flop to register 110 so that only this register accepts the digital output from register 100.

The signal on line 98 is also routed to flip-flop 152 by line 154, and this flip-flop changes state. The Q output goes from a logic Zero to a One and this level is applied by line 154 to video switch 44 (FIG. 2). The output of camera 18 is now switched into the monitor, and is displayed at the bottom of the screen. The target impact is again marked. This time the most significant bit on line 106 is a One and gate 142 is enabled. The signal from the light pen unit, applied on line 98, sets flip-flop 146. Register 112 is thus conditioned to receive and hold the digital positional signals from register 100.

The target impact has now been marked for both cameras. The Q outputs of flip-flops 146 and 148 are both Ones. The output of AND gate 156 therefore rises to a One which signal is sent out as a calculate comand to the rest of the computer. The digital data stored in registers 110 and 112 are thus processed, and then displayed to give miss distance. The output of gate 156 is also sent to the display logic to display the answer.

In moving target and similar applications, registers 110 and 112 preferably record data on moving target instantaneous position, while registers 114 and 115 are used to store target impact positional data. The last two registers are controlled by flip-flops 158 and 160, respectively. The input NAND gates 162 and 164 each have an additional enable input which is connected to the output NAND gate 156. Thus, registers 114 and 116 can be loaded only after registers 110 and 112 have been properly loaded, at which time the output of AND gate 156 is a One. The input signal of gate 162 is received from the output of gate 144 via inverter 166. Similarly, the signal applied to gate 164 comes from the output of gate 142 via inverter 168. The other enable input of gates 162 and 164 is connected to an output of shift register 170.

Shift register 170 serially loads Ones in response to clocking inputs applied on line 154. Initially, this shift register is in the reset position where all Zeros are loaded. The first clock pulse applied in response to actuation of the light pen in marking a target causes a One to be loaded into shift register 170. A One appears at output Q.sub.A. The second light pen marking loads another One and a One output also appears at Q.sub.B. If there is no moving target calculation involved, then the shift register advances no further and gates 162 and 164 do not become enabled. However, for moving target applications, once registers 110 and 112 have been loaded, the target impact is now marked for the first camera display. The signal from light pen 38 again clocks shift register 170 and a One appears at output Q.sub.C. This enables gates 162 and 164. The Zero signal out of gate 144 is inverted at 166 and applied to NAND gate 162. The output of gate 162 changes from a One to a Zero and sets flip-flop 158. Register 114 is thereby loaded with the data from register 100.

Flip-flop 152 is toggled by the marking signal on line 154 and the second camera output is now displayed. The operator marks impact position, again clocking shift register 170. However, because Q.sub.C is already loaded with a One, there is no change in output from Q.sub.C. Gate 164 remains enabled and the signal out of gate 142 is inverted and applied to this gate. Its output goes to Zero to set flip-flop 160. Register 116 is now conditioned to receive and hold the digital signals out of register 100.

The target impact has now been marked for both cameras and both inputs to AND gate 172 are a One. Its output goes to One and is used as a calculate command. The data in registers 114 and 116 are thus processed. Once the calculations are complete and have been displayed, the flip-flops and registers can be reset by depressing a manual switch. Preferably, this switch is on the shaft of light pen 38 so that it can be readily actuated by the observer.

This invention in its broader aspects is not limited to the specific details shown and described and departures may be made from such details without departing from the principles of the invention and without sacrificing its chief advantages.

Claims

What is claimed is:

1. A scoring system for a target range comprising:

a. means for viewing said range and the impact of weapons when such occur,

b. means for displaying the output of said viewing means,

c. a light pen unit responsive to the receipt of said viewing means output and the display of said displaying means for generating signals representative of impact location, and

d. means for receiving said signals generated by said light pen unit and calculating impact position.

2. A scoring system as claimed in claim 1, wherein:

a. said displaying means includes a video monitor having

1. a screen onto which an electron beam is directed during the scanning of the frame, and

b. said light pen unit includes

2. a manual probe capable of being disposed adjacent to the outside of said screen to sense the passage of the electron beam during scanning.

3. A scoring system as claimed in claim 2, wherein:

a. said light pen further includes

1. a pair of counters responsive to receipt of said viewing means output for accumulating counts proportional to the electron beam position during scanning, and

2. means responsive to the output of said probe for transferring the accumulated counts of said counters to said receiving and calculating means.

4. A scoring system as claimed in claim 3, wherein:

a. said viewing means comprises

1. a pair of television cameras, the output of each comprising a composite picture signal, including synchronizing pulses, which is transmitted to said monitor,

b. one of said pair of counters receives and counts synchronizing pulses in said composite picture signal for each line in the frame to accumulate a count proportional to the electron beam vertical position, and

c. the other of said pair of counters comprises a timing circuit which is actuated by each of said synchronizing pulse received from said camera to accumulate a count proportional to the electron beam horizontal position.

5. A scoring system as claimed in claim 4, wherein said light pen unit further includes:

a. a photosensitive detector connected to said probe to convert the light received by the passage of said electron beam into an electrical signal,

b. means responsive to the output of said counter and said photosensitive detector for latching the output of said counters at the counts accumulated at the time the probe senses the passing of the electron beam.

6. A scoring system as claimed in claim 5, wherein said transferring means includes:

a. a manually operable switch on said probe connected to transfer the latched count of said counters to said receiving and calculating means.

7. A scoring system as claimed in claim 6, wherein:

a. said receiving and calculating means includes

1. a pair of registers, each of said registers being connected to the output of the light pen unit to store a count proportional to electron beam horizontal position in response to actuation of said manually operable switch, and

2. means for electronically processing said stored counts to calculate impact position.

8. A scoring system as claimed in claim 7, wherein:

a. said light pen unit additionally generates signals representative of the instantaneous position of a moving target, and

b. said receiving and calculating means further includes:

1. a second pair of registers, each of said second pair of registers being connected to the output of the light pen unit to store a count proportional to electron beam horizontal position in response to actuation of said manually operable switch, and

2. second means for electronically processing the stored counts in said second pair of registers to calculate instantaneous position of the moving target.

9. A scoring system as claimed in claim 7, further comprising:

a. a video switch connected to the output of said pair of cameras,

b. means for actuating said video switch for sequentially applying to said monitor for display the composite picture signal from said pair of cameras.

10. A scoring system as claimed in claim 9, wherein:

a. said actuating means is connected to said electronic processing means so that the video switch automatically switches from one camera to the other camera in said pair following application of the counts associated with said one camera into one of said registers whereby the counts obtained responsive to both camera outputs are sequentially derived and stored in said registers.

11. A scoring system as claimed in claim 10, wherein said processing means includes:

a. means for initiating processing of the contents of said registers after counts have been obtained in said registers representative of impact position as viewed by both cameras.

12. A scoring system as claimed in claim 11, further comprising:

a. coaxial cables linking said cameras to said monitor for transmission of the composite picture signals.